Soft Tissue Masses of the Hand

Abstract

Solid soft tissue masses of the hand represent a diverse group of lesions, most of which are benign. Accurate diagnosis is essential to guide management and avoid unnecessary or inappropriate surgical intervention. This review discusses solid soft tissue tumors of the hand in accordance with the 2020 World Health Organization Classification of Soft Tissue Tumors, emphasizing imaging features and clinical presentation, as well as the current European Society of Musculoskeletal Radiology guidelines from 2023 for primary imaging of soft tissue lesions. Characteristic imaging features help diagnose common entities such as lipomas, tenosynovial giant cell tumors, glomus tumors, and nerve sheath tumors. Various pseudolesions (e.g., traumatic neuromas) are also discussed. The importance of referral to specialized sarcoma centers for indeterminant or aggressive lesions is highlighted.

Keywords

soft tissue lesions - hand - ultrasound - magnetic resonance imaging

Patient Presentation

Anamnesis, Clinical Findings, and Image Presentation

A 49-year-old patient presented with clinical signs of carpal tunnel syndrome persisting for 2 months. He had a history of surgical removal of a lipofibromatous hamartoma 3 years prior. The patient reported progressive bulging at the entrance of the carpal tunnel, accompanied by a distinctly positive Hoffmann-Tinel sign. Clinical examination revealed progressive atrophy of the intrinsic hand muscles innervated by the median nerve.

Image Interpretation

Ultrasound (US) and magnetic resonance imaging (MRI) revealed a markedly enlarged median nerve extending over ∼ 16 cm ([Fig. 1A, B]). The nerve exhibited a prominent, inhomogeneous fascicular architecture, characterized by thickened cable-like nerve fascicles and increased hypertrophic, echogenic epineural fatty tissue. The superficial thenar musculature showed pronounced fatty atrophy, indicative of chronic denervation due to involvement of the recurrent motor branch. These findings are consistent with chronic compression of nerve fascicles within the carpal tunnel, clinically mimicking carpal tunnel syndrome.

Fig. 1 Lipofibromatous hamartoma of the median nerve. A 49-year-old patient presented with carpal tunnel syndrome, including atrophy of the thenar muscles. (A) Axial ultrasound (18 MHz) reveals an increased volume of the median nerve (encircled). The nerve fascicles are thickened and hypoechogenic (arrow) and surrounded by hyperechogenic tissue. (B) Axial magnetic resonance imaging (T2-weighted fast spin echo) showing the markedly thickened median nerve (encircled). The nerve fascicles appear clearly thickened and hyperintense (arrow). They are surrounded by equally hyperintense tissue (arrow). In the coronal and sagittal planes (not shown), the lesion's longitudinal extent is ∼ 15 cm.

Final Diagnosis

Even though the patient was unusually old at the time of diagnosis, the symptoms and US and MRI findings clearly supported the diagnosis of a lipofibromatous hamartoma of the median nerve.

Introduction

Soft tissue tumors originate from nonepithelial extraskeletal tissues, such as fat, muscle, tendons, peripheral nerves, blood vessels, and fibrous tissue.[1] More than 15% of soft tissue tumors occur in the hand, and, among these, ∼ 95% are benign.[2] This review discusses soft tissue masses of the hand in accordance with the revised 2020 World Health Organization (WHO) Classification of Soft Tissue Tumors, as well as other soft tissue masses of varying origin that may be encountered in both routine and unusual clinical practice. The 2020 WHO classification ([Table 1]) organizes soft tissue tumors into 11 categories and further stratifies them by biological behavior into benign, intermediate (locally aggressive), and malignant entities.[3]

Table 1 Characteristics of six solid soft tissue types cited in the text[a]

Category	Benign	Locally aggressive	Malignant
Adipocytic	Lipoma	Atypical lipomatous tumor	Liposarcoma
Fibroblastic and myofibroblastic		Palmar fibromatosis	Epithelioid sarcoma Solitary fibrous tumor, malignant
Fibrohistiocytic tumors	Tenosynovial giant cell tumor
Pericytic tumors	Glomus tumor
Peripheral nerve sheath tumors	Schwannoma Neurofibroma		Malignant peripheral nerve sheath tumor
Tumors of uncertain differentiation			Synovial sarcoma

^a According to the 2020 World Health Organization Classification of Soft Tissue Tumors.

Imaging Recommendations According to the 2023 Guidelines of the European Society of Musculoskeletal Radiology

For the primary diagnosis of local soft tissue tumors, the radiologist should carefully consider the patient's medical history. Relevant aspects include the time of initial detection, any recent changes in size, and a history of trauma or previous surgery in the affected region. However, it is crucial that diagnostic evaluation not be delayed based solely on the patient's subjective attribution of the lesion to a traumatic event because it may lead to misinterpretation or underestimation of a potentially serious pathology.[4]

Ultrasound

According to the 2023 European Society of Musculoskeletal Radiology (ESSR) guidelines, US is the appropriate first-line imaging modality for suspected soft tissue tumors that are < 5 cm and located superficially.[4] A high-frequency linear transducer (10–20 MHz) is recommended for optimal evaluation of these lesions.[5] If the lesion is superficial and demonstrates typical sonographic features, US can often provide a reliable diagnosis without the need for further imaging.[6] Doppler US plays a crucial role in characterizing soft tissue masses. In particular, vascular malformations may demonstrate slow filling during dynamic assessment with compression and release maneuvers.[5]

Benign lesions with characteristic US features, such as anechoic, avascular well-circumscribed cystic structures, can be confidently diagnosed as simple cysts or synovial/ganglion cysts. Other benign entities, such as superficial lipomas, superficial fibromatosis, and foreign body granulomas (when clinical history supports the diagnosis), may also be accurately assessed with US.[4] In cases where US findings are inconclusive, or if the lesion demonstrates atypical features, MRI and/or biopsy should be pursued to establish a definitive diagnosis. In addition, small superficial lesions that appear benign but show interval growth warrant biopsy. For lesions measuring < 2 to 3 cm, an excisional biopsy may be considered appropriate.[4] [7]

Magnetic Resonance Imaging

In cases of clinical suspicion of malignancy, history of rapid growth, primary osseous or joint involvement, and lesion size > 5 cm, MRI should be chosen over US as the imaging modality. Furthermore, MRI should be performed before biopsy.[4] The recommended field strength for evaluating soft tissue tumors is at least 1.5 T.

The basic imaging protocol should include T1-weighted and fluid-sensitive fat-saturated sequences, both oriented parallel to the long axis of the tumor. Axial sequences with high spatial resolution are necessary to delineate the lesion's margins accurately and assess involvement of adjacent compartments, neurovascular structures, bone, and joints.[4]

Following intravenous gadolinium administration, dynamic contrast-enhanced sequences may help differentiate benign from malignant soft tissue tumors. Subtraction techniques are particularly useful in lesions with intrinsically high signal intensity on T1-weighted images, such as melanin or methemoglobin-containing entities.[4] A cutaneous marker should be applied before the examination to aid in localization.[4]

Projection Radiographs

Radiographs help identify intralesional mineralization patterns and assess potential bone involvement associated with soft tissue masses. Radiographs should be obtained in at least two orthogonal views.[4]

Soft Tissue Masses: An Overview

Adipocytic Tumors

Lipoma

Pathology

Lipomas are benign adipocytic tumors composed of mature adipose tissue, originating from mesenchymal preadipocytes.[5] [8] They typically present as soft painless masses and can occur in either subcutaneous or deeper locations. Importantly, they do not infiltrate the surrounding tissue.[5] [9] Although lipomas are the most common soft tissue tumors, they are relatively rare in the hand, accounting for only 1 to 3.8% of soft tissue tumors in that region. In the fingers, lipomas are extremely rare, with an incidence of ∼ 1%.[5] [8] [10] In the hand, lipomas most commonly occur intramuscularly at the thenar and hypothenar eminences, where they may cause paresthesia due to compression of adjacent nerve branches. Other common locations include the carpal tunnel and Guyon's canal.[11] The recommended treatment is excisional biopsy or marginal excision, particularly in cases where the lesion is close to a nerve. Recurrence rates are > 5% in such cases.[7] [9] [11]

Imaging

On US, lipomas present as well-defined typically homogeneous and hyperechoic lesions, although they may also appear hypo- or isoechoic.[5] On MRI, they demonstrate homogeneous high signal on T1-weighted sequences and low signal intensity on T2-weighted fat-saturated sequences. They characteristically have low apparent diffusion coefficient values and demonstrate no or only minimal contrast enhancement.[5]

Atypical Lipomatous Tumors and Liposarcomas

Pathology

Liposarcomas make up 20% of all mesenchymal malignant tumors and are classified into five subtypes[12]: well-differentiated liposarcoma (WDLS), dedifferentiated, myxoid, pleomorphic, and myxoid pleomorphic liposarcoma.[1] Depending on their anatomical location, WDLS are referred to as atypical lipomatous tumors (ALTs) when arising in the extremities, chest wall, or abdominal wall.[13] The ALTs most frequently occur in the extremities, particularly the lower limbs, with only a few cases reported in the hand.[14] [15]

Imaging

On MRI, a tumor length > 10 cm and the presence of thick septa or nonfatty areas are associated with ALT. The nonfatty nodules correspond to regressive changes with fat necrosis, calcification, fibrosis, inflammation, and myxoid changes. Dedifferentiated nodules arising in ALT of the hand are extremely rare.[13]

Lipofibromatous Hamartoma

Pathology

A lipofibromatous hamartoma (LFH) is a rare benign neoplasm composed of fibroadipose tissue that affects peripheral nerves, most frequently in the upper extremity. Among the nerves of the upper limb, the median nerve is most commonly involved, although the radial nerve, ulnar nerve, digital nerves, and brachial plexus may also be affected.[16] The lesion is believed to be congenital and tends to grow very slowly. Typically, a long-standing history of a painless mass dates back to childhood, with patients often becoming symptomatic in the third or fourth decade of life.[17] When the median nerve is affected, patients frequently present with symptoms of carpal tunnel syndrome.[16] Clinically, LFH is often associated with macrodactyly that occurs in ∼ 30% of cases.[18]

Imaging

On US ([Fig. 1A]), LFH has a characteristic appearance. The affected nerve appears enlarged with multiple hypoechoic coaxial “cables” surrounded by a hyperechoic rim. On MRI ([Fig. 1B]), the imaging modality of choice for surgical planning, an enlarged nerve containing 15 to 16 coaxial cable-like structures is revealed. These represent 2- to 3-mm axonal bundles encased in epineural fibrous tissue and surrounded by fat. In most cases, the imaging findings are so typical that biopsy is not required.[16]

Fibroblastic and Myofibroblastic Lesions

Palmar Fibromatosis

Pathology

Palmar fibromatosis, also known as Dupuytren's disease or Dupuytren's contracture, is a common condition. It is a benign fibroproliferative disorder characterized by the formation of subcutaneous fibrous nodules with involvement of the palmar aponeurosis and variably the subcutis and dermis. In progressive stages of the disease, cordlike attachments may develop along the flexor tendons, ultimately resulting in flexion contractures of the fingers.[19] According to a 2020 meta-analysis, the worldwide prevalence is 8.2%.[20] It affects ∼ 20% of individuals > 65 years of age and is associated with other fibromatoses, as well as systemic conditions such as diabetes mellitus, alcohol abuse, and epilepsy.[19] The disease is classically divided into three stages: proliferative, involutional, and residual.[20] These lesions are typically situated immediately superficial to the flexor tendons, most frequently in the region of the distal metacarpal bones.

Imaging

The US features ([Fig. 2A]) vary depending on the disease stage. In the proliferative phase, the nodules, typically located over the metacarpophalangeal and proximal interphalangeal joints, appear hypoechoic relative to the flexor tendons. During the involutional and residual phases, as collagen production increases and the nodules contract, they become iso- to hyperechoic compared with the surrounding tendons.[20]

Fig. 2 Palmar fibromatosis. A 52-year-old patient presents with thickening and nodular skin changes on the palmar aspect of the hand, 2 years after carpal tunnel release surgery. (A) On ultrasound, a hypoechoic structure is identified superficial to the flexor tendon, in contact with the palmar aponeurosis. In the accompanying illustration, the red structure represents the flexor tendon; the blue structure indicates the fibromatous nodule. (B) Magnetic resonance imaging of the hand demonstrates a T2-hypointense subcutaneous nodule. The arrow indicates the palmar aponeurosis.

On MRI ([Fig. 2B]), palmar fibromatosis appears as focal nodules or cordlike structures arising from the palmar aponeurosis. These lesions are generally of low signal on T1-weighted images. Lesions with high cellularity may show relatively increased signal intensity on T2-weighted images, whereas lesions with a predominantly collagenous matrix tend to remain low in signal on T2-weighted sequences.[5] [21] They usually exhibit no internal vascularization. In a study by Morris et al, only 3 of 54 lesions demonstrated hypervascularity. Calcifications may also be present within the nodules.[19]

Epithelioid Sarcoma

Pathology

Epithelioid sarcoma is a rare type of sarcoma, accounting for ∼ 1% of all adult soft tissue sarcomas. It is a slow-developing malignant tumor that typically occurs in the distal extremities. Histopathologically, epithelioid sarcoma may be mistaken for benign conditions such as Dupuytren's disease. The peak incidence is reported at ∼ 35 years of age. The two morphological variants are (1) a proximal type that presents as deep infiltrating soft tissue masses in the midline of the trunk, proximal limbs, or limb girdles, and (2) a classic or distal type. The distal type presents as superficial slow growing painless nodules that may lead to chronic nonhealing ulcers. In up to 27% of cases, it is associated with previous trauma or scar tissue. Initial treatment involves wide local excision or amputation, with or without adjuvant radiotherapy.[22]

Imaging

On MRI ([Fig. 3]), the classic type typically appears as a mass with heterogeneous signal intensity, often infiltrating along fascial planes and neurovascular bundles. Imaging is essential to assess the extent of the entity accurately.[22]

Fig. 3 Epithelioid sarcoma. A 21-year-old woman presents with a subcutaneous lesion on the palmar surface of the right hand that she had first noticed 2 years earlier; however, biopsy was delayed. Over the past 2 years it has shown slow growth. Biopsy revealed epithelioid sarcoma. (A) Axial T2-weighted image depicts the lesion (arrow) when it was first noticed. (B–D) Magnetic resonance imaging of the lesion at the time of biopsy. (B) The lesion is hyperintense on proton-density-weighted Spectral Adiabatic Inversion Recovery (SPAIR), (C) hypointense on T1–weighted sequence (red circle), and (D) shows marked contrast enhancement (red arrow). The mass is infiltrating all the thenar muscles as well as the cutis and subcutis. In addition, denervation edema of the thenar musculature is observed, raising suspicion for involvement of the motor thenar branch of the median nerve.

Solitary Fibrous Tumor, Malignant

Pathology

A solitary fibrous tumor (SFT) is a rare fibroblastic mesenchymal tumor that can arise in any anatomical location, with an estimated incidence of only one new case per million people per year.[23] [24] According to the fifth edition of the WHO Classification of Soft Tissue and Bone Tumors, extracranial SFTs are categorized as benign SFT (intermediate category, locally aggressive), SFT not otherwise specified (intermediate category, rarely metastasizing), and malignant SFT. Local recurrence or distant metastasis occurs in ∼ 10 to 40% of patients with SFT.[24] Due to the variable clinical behavior of SFTs, it remains challenging to determine which tumor- and patient-specific factors predict aggressive progression. As a result, several risk stratification models have been developed to estimate the individual risk of recurrence or metastasis.[24] [25]

Imaging

On MRI ([Fig. 4]), SFTs typically appear homogeneously isointense to muscle on T1-weighted images and show variable signal intensity on T2-weighted sequences. A low T2 signal indicates higher cellularity and less fibrosis, whereas myxoid changes result in markedly high T2 signal intensity. Following intravenous gadolinium administration, SFTs usually demonstrate strong contrast enhancement.[26]

Fig. 4 Malignant solitary fibrous tumor. A 34-year-old patient presents with a progressively enlarging lesion surrounding the metacarpal thumb area. There is no restricted range of motion. (A) The lesion is inhomogeneously hyperintense on a coronal proton-density-weighted image and (B) nearly isointense to muscle on a axial T1-weighted image. (C) The postcontrast T1-weighted sequence demonstrates an inhomogeneously marked enhancement.

Fibrohistiocytic Tumors

Tenosynovial Giant Cell Tumor

Pathology

A tenosynovial giant cell tumor (TSGCT) is the second most common benign tumor of the hand, typically affecting patients from 30 to 50 years of age, predominantly female.[27] [28] Various theories exist regarding its pathophysiology, including neoplastic, inflammatory, trauma related, immune mediated, or association with abnormal lipid metabolism. The most widely accepted theory describes it as a reactive or regenerative hyperplasia accompanied by an inflammatory process. Recent literature has identified a chromosomal translocation involving chromosome 1p13 in most tumors.[27] [29]

In the hand, TSGCT most commonly presents in its localized form as focal masses associated with tendons. A single nodule typically is present, although multiple nodules may occur. Clinically, they appear as firm, painless swellings over the flexor aspect of the hand.[3] [27] [29] A TSGCT is classified into nodular and diffuse types according to Al-Quattan's classification.[29] Diffuse-type TSGCT often infiltrates nearby soft tissues and joints, making surgical removal more complicated. Treatment consists of marginal excision with clear margins.

Although the lesion is benign, the incidence of local recurrence is high, with rates of up to 44%.[27] [30] Risk factors for local recurrence are adjacent degenerative joint disease, localization at the distal interphalangeal joint or the interphalangeal joint of the thumb, increased cellularity and mitotic activity, and tumor subtype.[27] [29] In incidences of diffuse-type TSGCT, regular MRI follow-up is necessary to monitor recurrence.[30]

Imaging

On radiographs, TSGCT exhibits soft tissue density or may cause bony erosions.[29] On US, TSGCT presents as hypoechoic masses adjacent to the tendon sheath and shows internal vascularization. On dynamic US, they do not move with the underlying tendon.[28] On MRI, the lesions demonstrate low signal intensity on both T1- and T2-weighted images due to the presence of hemosiderin. Importantly, blooming artifacts are common on gradient-echo sequences as a result of hemosiderin deposition. Following intravenous contrast administration, enhancement is typically observed.[28] [31]

Pericytic Tumors

Glomus Tumor

Pathology

Glomus tumors are benign vascular neoplasms that arise from the glomus body, a neuro-myovascular structure involved in thermoregulation. They account for ∼ 1 to 5% of soft tissue tumors of the hand.[32] About 75% of glomus tumors occur in the hand, and nearly all of these are located in the subungual region.[33] Glomus tumors are more common in women between 30 and 50 years of age and usually not associated with other conditions.[34] Clinical features include blue discoloration of the nail, nail deformity, and a palpable nodule.[34]

Solitary glomus tumors, which are more frequent, present with the classic triad of localized tenderness, severe pain, and sensitivity to cold.[32] An association between glomus tumors and neurofibromatosis type 1 (NF1) was also reported.[35] Treatment consists of complete surgical excision. Reported recurrence rates in the literature range from 4% to 50%, and a distinction is made between early recurrence, often attributed to incomplete excision, and late recurrence that may represent a new lesion developing adjacent to the original excision site.[32]

Imaging

On US, glomus tumors appear as hypoechoic solid masses with increased through transmission and small cystic components, showing marked blood flow on both power and color Doppler imaging. On MRI, they demonstrate high signal intensity on T2-weighted images, intermediate signal on T1-weighted images, and enhancement following intravenous gadolinium administration. Small glomus tumors (< 1 cm) typically show homogeneous enhancement. Magnetic resonance imaging is particularly useful in identifying tumor recurrence.[33]

Peripheral Nerve Sheath Tumors

Peripheral nerve sheath tumors (PNSTs) of the hand account for < 5% of all tumors arising from the hand. The overwhelming majority of these tumors are benign, and the incidence of malignant peripheral nerve sheath tumors (MPNSTs) is extremely low. Benign PNSTs of the hand consist mainly of schwannomas, neurofibromas, and perineuriomas.[36] Most of the lesions occur sporadically and are not associated with NF.[10] A PNST usually presents in adulthood between 20 and 30 years of age.[5] The typical clinical presentation is a slow-growing soft tissue mass, with pain and sensory loss or weakness in the hand. In case of large size (> 5 cm), rapid size progression, or an increase in pain, MPNST must be considered. A positive Hoffmann-Tinel sign of the tumor is common. Therapy of these tumors depends on the symptoms, such as pain or neurologic deficits.[5] [36]

Schwannoma (Neurinoma)

Pathology

Schwannomas arise from Schwann cells that surround peripheral nerves and tend to originate from deeper and larger nerves, particularly the ulnar nerve.[5] They are the most common benign PNSTs, accounting for ∼ 5% of all soft tissue tumors, and can occur throughout the body. Between 3% and 19% of schwannomas develop in the upper extremities.[36] [37] These tumors can occur at any age and have no sex predilection.[36] Although most cases are sporadic, schwannomas may also be associated with genetic conditions such as NF2 and, less commonly, NF1.[37] Clinically, schwannomas typically present as a slow-growing mass, often accompanied by paresthesia in the distribution of the affected nerve.[38]

Imaging

On US, neurogenic tumors generally appear as fusiform masses with a “dural tail sign,” representing the entering and exiting nerve fascicles. Schwannomas are usually eccentric relative to the parent nerve, helping differentiate them from neurofibromas. In case of internal cystic changes, necrosis, or hemorrhage, they show a heterogeneous echogenicity.[5]

On MRI, schwannomas typically appear iso- to hypointense on T1-weighted images and hyperintense on T2-weighted sequences, with postcontrast enhancement. Heterogeneous signal intensity and enhancement suggest internal hemorrhage or myxoid/cystic degeneration. Additional imaging signs, not specific to schwannomas but may be present in other neurogenic tumors, include the “target sign” (a central low to intermediate T2 signal indicating fibrous tissue and a peripheral high T2 signal indicating myxoid tissue).[37] The MRI features more suggestive of schwannoma are the “bright rim sign” (peripheral high T2 signal), the absence of significant peritumoral edema, and a non-lobulated shape.[37]

Neurofibroma

Pathology

Neurofibromas are relatively common benign PNSTs. Differentiation between schwannomas and neurofibromas is clinically important because neurofibromas contain intratumoral nerve fibers. Neurofibromas are classified into four subtypes based on anatomical location and gross appearance: plexiform neurofibromas; intraneural neurofibromas; massive soft tissue neurofibromas; and localized cutaneous neurofibromas, with this last one the most common type.[36] Plexiform neurofibromas are considered pathognomonic for NF1 ([Fig. 5A]) and carry an increased risk of malignant transformation.[39]

Fig. 5 Neurofibroma. A 58-year-old patient with known neurofibromatosis type 1 and numerous cutaneous neurofibromas presented with a rapidly enlarging, painful mass on the palm. Due to the clinical signs of rapid growth, pain, and ulceration, features that are concerning for malignant peripheral nerve sheath tumor, surgical excision was performed. Histopathologic analysis confirmed a benign neurofibroma with no evidence of malignant transformation. (A) Palmar view of the hand showing multiple nodules and a surface ulceration. (B) Ultrasound revealed an inhomogeneously hypoechoic lesion with cystic components and internal vascularization. (C) Fluorodeoxyglucose positron emission tomography/computed tomography demonstrates a maximum standardized uptake value of 5.5 g/mL, indicated by the red arrow. The black arrows indicate the numerous cutaneous neurofibromas.

Neurofibromas typically occur in a younger population, most often in the third to fourth decade of life, and show no sex predilection.[36] Most neurofibromas occur sporadically, with only ∼ 10% associated with NF1.[40] In the hand, neurofibromas often arise near flexion creases and cutaneous nerves.[41] Clinically, they present as nodules that may cause varying degrees of pain or peripheral nerve dysfunction.[41]

Imaging

On US ([Fig. 5B]), plexiform neurofibromas appear as predominantly hypoechoic, well-confined masses arising from multiple nerve fascicles. Neurofibromas are characteristically concentric relative to the nerve, in contrast to schwannomas that tend to be eccentric. In addition, neurofibromas typically involve multiple fascicles, unlike schwannomas that are more often limited to a single fascicle.[36] [39]

On MRI, the “target sign,” a central low T2 signal and peripheral high T2 signal, can be seen in neurofibromas, as well as other neurogenic tumors, although it is observed less frequently in neurofibromas compared with schwannomas on MRI.[41] Fluorodeoxyglucose positron emission tomography/computed tomography ([Fig. 5C]) can help distinguish between neurofibroma and neurofibromatosis based on the number of lesions present.

Malignant Peripheral Nerve Sheath Tumor

Pathology

Malignant peripheral nerve sheath tumors are rare, accounting for ∼ 3 to 10% of all soft tissue sarcomas. These tumors are highly malignant with a strong tendency for local recurrence and distant metastasis. In 25 to 50% of cases, MPNSTs are associated with NF1, the most significant risk factor for their development. Among NF1 patients, deep-seated plexiform neurofibromas carry the highest risk for malignant transformation.[42]

Imaging

On US, MPNSTs typically appear as irregularly shaped masses with a heterogeneous internal echotexture, infiltrative borders, and disruption of normal fascicular architecture. Magnetic resonance imaging often reveals heterogeneous lesions with an iso- to hypointense signal on T1-weighted images relative to muscle and a hyperintense signal on T2-weighted images. Following intravenous gadolinium administration, MPNSTs exhibit marked, often irregular or nodular enhancement. Peritumoral soft tissue edema is a common associated finding.[43]

Traumatic Neuroma

Pathology

Traumatic neuromas are hyperplastic reparative proliferations of peripheral nerves that develop following injury, and they typically present as nodular soft tissue masses. Clinically, they most often manifest with painful hypersensitivity and a positive Hoffmann-Tinel sign.[44] Based on the mechanism of injury, traumatic neuromas are classified into two primary types: terminal neuromas and neuromas-in-continuity. The latter can result from either total or partial nerve transection or from repetitive blunt trauma. Fusiform neuromas are commonly seen following nerve transection, particularly involving the digital nerves.[44]

Imaging

On US, traumatic neuromas appear as well-defined hypoechoic or mixed-echogenicity nodules located along the expected course of the affected nerve.[45] Magnetic resonance imaging typically demonstrates these lesions as isointense to skeletal muscle on T1-weighted images, hyperintense on T2-weighted sequences, with contrast enhancement following intravenous gadolinium administration.[45]

Tumors of Uncertain Differentiation

Synovial Sarcoma

Pathology

The term synovial in synovial sarcoma is a misnomer because the tumor does not arise from synovial tissue. Instead, those sarcomas are categorized as mesenchymal spindle cell tumors displaying varying degrees of epithelial differentiation.[46] [47] Soft tissue sarcomas are rare malignant tumors, accounting for < 1% of newly diagnosed cancers annually. Approximately 60% of soft tissue sarcomas arise in the extremities, with 15 to 25% affecting the upper limb and only 5 to 10% involving the hand or wrist.[48]

Although synovial sarcoma can occur at any age, it most commonly affects children and young adults, with a peak incidence in the fourth decade of life.[46] Early diagnosis is often challenging because the clinical symptoms of synovial sarcoma are nonspecific and can mimic benign conditions such as trauma, myositis, bursitis, or tendinitis, frequently leading to misdiagnosis. The initial growth is often slow, and some patients also report long-standing pain at the site of the tumor before the appearance of noticeable swelling.[46] [49] The imaging characteristics of synovial sarcomas are variable, ranging from nonaggressive to more aggressive features.[47] Due to their typically small initial size (often < 5 cm), gradual growth, and well-defined margins, these lesions are sometimes misclassified as benign.[47] Making an early diagnosis is pivotal. Patients with advanced synovial sarcoma have a poor prognosis compared with those presenting with local disease.[46]

Imaging

On radiographs, ∼ 30% of synovial sarcomas demonstrate calcifications that often appear in an eccentric or peripheral distribution relative to the soft tissue mass. The presence of fine stippled calcifications can be considered suspicious for synovial sarcoma.[47] On MRI ([Fig. 6]), small synovial sarcomas may appear relatively homogeneous, demonstrating marked hyperintensity on T2-weighted fat-suppressed sequences and hypointensity on T1-weighted images.

Fig. 6 Synovial sarcoma. A 24-year-old patient with a painless, slowly growing mass on the volar aspect of the wrist. (A) Magnetic resonance imaging demonstrates a well-defined, markedly hyperintense lesion (encircled) on proton-density-weighted images and (B) a hypointense signal on T1-weighted images. (C) There is strong contrast enhancement following intravenous gadolinium administration.

This imaging profile can closely resemble benign entities such as ganglia or synovial cysts, posing a significant diagnostic pitfall. However, following intravenous gadolinium administration, synovial sarcomas usually exhibit prominent and heterogeneous contrast enhancement, aiding in differentiation from benign lesions.[28] Typical imaging signs, such as the “triple sign,” referring to pronounced heterogeneity on T2-weighted images, and the “bowl-of-grapes sign,” characterized by features such as hemorrhage and fluid-fluid levels, are often absent when synovial sarcoma occurs in the hand, further complicating the diagnosis.[47]

Metastases

Pathology

Metastases of the hands are exceedingly rare, accounting for ∼ 0.1% of all metastatic lesions. These metastases may present with nonspecific symptoms, such as pain, tenderness, palpable masses, and ulceration, that can lead to misdiagnosis as infectious or inflammatory conditions, thereby delaying appropriate treatment.[50] [51] In a descriptive study published in 2021, Cattelan and Dumontier reviewed 337 studies comprising 452 cases of hand metastases. The most common primary tumor was lung cancer (40%), followed by gastrointestinal, genitourinary, gynecologic, and ear, nose, and throat malignancies. Of the reported cases, 59% involved osseous metastases; 31% were soft tissue metastases.[52] Acral metastases generally carry a poor prognosis because they typically reflect widespread disease dissemination. The mean survival following the diagnosis of hand metastasis was reported to be ∼ 7 months[51] [52] ([Fig. 6A, B]).

Imaging

Metastases usually appear as osteolysis on radiography ([Fig. 7A]) and less frequently as osteoblastic lesions (e.g., in prostate cancer). The distal phalanges are more frequently affected due to their greater blood supply. On MRI ([Fig. 7B]), metastases differ from normal bone marrow in their signal intensity. Magnetic resonance imaging is particularly useful for evaluating extraosseous metastatic components.

Fig. 7 Metastasis of adenocarcinoma of the lung. A 65-year-old patient with a history of recurrent tenosynovitis of both hands presents to an orthopedic specialist after experiencing a sudden onset of sharp, severe pain in the right hand while performing household activities. (A) Dorsovolar radiography reveals a pathologic fracture of the second metacarpal. (B) Subsequent magnetic resonance imaging demonstrates a 3 × 2 × 2-cm lesion located in the metadiaphysis of the second metacarpal (arrow), with a substantial extraosseous soft tissue component. Histopathologic analysis confirmed the lesion to be a metastasis from a moderate to poorly differentiated adenocarcinoma of the lung.

Tumor-simulating Lesions (Pseudotumors)

Lobular Capillary Hemangioma

Pathology

Lobular capillary hemangioma is a benign, rapidly growing vascular proliferation that manifests on the skin, the subcutaneous tissue, or the mucous membranes.[53] [54] The often used term pyogenic granuloma is a misnomer because the condition is neither pyogenic nor granulomatous. Histologically, it consists of clusters of hyperplastic capillaries separated by a lobule containing a central feeder vessel.[54] Clinically, it is a smooth, red to purple, sessile or pedunculated lesion. There is a history of rapid growth, usually a few weeks.[53] Common complications are bleeding and ulceration.[54]

The exact etiology is unknown; however, theories about the underlying cause are minor trauma, chronic wounds, and viral infections.[53] The occurrence of lobular capillary hemangioma in the finger is more commonly associated with trauma than occurrence at other sites.[54] The treatment options are surgical excision, cryotherapy, curettage, laser, sclerotherapy, and microembolization. Most cases require therapy, and only a few may resolve spontaneously. A wide range of recurrence rates between 3.7% and 43.5% have been described.[53] Of the different treatment options, surgical management shows the lowest recurrence rate.[53]

Imaging

On US ([Fig. 8]), lobular capillary hemangioma is a heterogeneous, mainly hypoechoic, well-defined mass with abundant blood flow signals within the lesion on color Doppler flow.[55]

Fig. 8 Lobular capillary hemangioma. A 15-year-old patient presents with an exophytic mass on the volar aspect of the middle finger of the right hand. The lesion had developed rapidly 2 months ago following minor (bagatelle) trauma. (A) Photograph showing a pulp, or “berry,” located on the volar side of the middle finger. (B, C) On ultrasound, the mass appeared as a sharply demarcated, slightly inhomogeneous lesion (B, arrow) with pronounced internal vascularization (C).

Gout

Pathology

Gout is the most common cause of inflammatory arthritis in both men and women, with a rapidly increasing incidence attributed to the global rise in associated conditions, such as obesity, insulin resistance and metabolic syndrome, hypertension, and chronic kidney disease. Over recent decades, the incidence of gout has tripled.[56] [57] The disease progresses through several stages: initial asymptomatic hyperuricemia, followed by acute gout flares characterized by marked pain and inflammation, and, if inadequately managed, chronic tophaceous gout develops.[58]

The gold standard for diagnosis remains the identification of monosodium urate (MSU) crystals in synovial fluid using polarized light microscopy. However, this method has limitations, including the technical difficulty of joint aspiration, especially in small joints, and the potential for false-negative results in up to 25% of cases. In addition, MSU crystals can deposit in extra-articular soft tissues such as tendons and ligaments.[58]

Imaging

Ultrasound can depict the three principal components of tophi: the central crystal and debris core, the surrounding fibrovascular matrix, and the peripheral granulation tissue. The tophi present as well-circumscribed lesions containing bright echogenic crystals interspersed with hypoechoic septa that may demonstrate internal vascularity on Doppler imaging. The surrounding granulation tissue is typically seen as a hypoechoic halo.[57] [59]

On radiographs, tophi appear as high-attenuation soft tissue foci. On conventional computed tomography (CT), tophi appear as nodules or masses with a density of ∼ 160 to 170 HU, lower than that of typical calcifications. However, internal calcium deposition can lead to inhomogeneous density, making differentiation from other calcified lesions challenging on standard CT.[58] Dual-energy computed tomography (DECT) allows accurate identification of MSU crystal deposition, confirming the diagnosis of gout. The tophi appear as dense soft tissue lesions with MSU deposits that by definition are color-coded green.[59] Dual-energy computed tomography is highly specific and effective across all phases of gout, although its sensitivity may be reduced in early-stage disease.[58]

Rheumatoid Nodules

Pathology

Rheumatoid arthritis is a chronic systemic autoimmune disease characterized by synovial inflammation. Rheumatoid nodules are subcutaneous masses that occur in up to 35% of patients over the course of the disease.[60] These nodules most commonly develop over extensor surfaces and pressure points, including the fingers, hands, and elbows.[58]

Imaging

On US, rheumatoid nodules appear as oval homogeneously hypoechoic masses that are closely associated with the bone surface.[61] On MRI, they demonstrate iso- to hypointense signal on T1-weighted images relative to skeletal muscle, with variable T2 signal intensity depending on the degree of necrosis. Following intravenous gadolinium administration, enhancement may vary depending on the lesion's internal composition.[62]

The Role of Tumor Centers

According to the 2023 ESSR guidelines, referral to a specialized sarcoma treatment center is recommended for any patient who presents with a soft tissue tumor measuring ≥ 5 cm that demonstrates indeterminant or suspicious findings on US or MRI, or in cases with a clinical suspicion of malignancy. Importantly, patients suspected of having a sarcoma should be referred to a sarcoma reference center before undergoing biopsy or surgical intervention. Early referral helps prevent diagnostic delays and unplanned excisions, commonly referred to as “whoops procedures.” Biopsy of suspected appendicular soft tissue sarcomas should be performed by a radiologist with tumor expertise, using image-guided techniques. In cases where surgery has been performed without prior referral, patients must be promptly directed to a sarcoma center for further evaluation and appropriate management.[4]

Conclusion

• The 5-cm size threshold commonly used to distinguish benign from malignant soft tissue tumors does not apply to hand lesions because even small tumors often become clinically apparent due to their location.

• Smooth margins do not exclude malignancy; well-defined lesions can still be aggressive or malignant.

• When evaluating a suspected ganglion cyst, always consider alternative diagnoses. Misidentifying a synovial sarcoma as a benign ganglion is a critical diagnostic pitfall.

Conflict of Interest

None declared.

• References

• 1 Sbaraglia M, Bellan E, Dei Tos AP. The 2020 WHO Classification of Soft Tissue Tumours: news and perspectives. Pathologica 2021; 113 (02) 70-84
• 2 AbuMoussa S, Roshan MP, Souza FF. et al. Soft tissue masses of the hand: a review of clinical presentation and imaging features. Curr Oncol 2023; 30 (02) 2032-2048
• 3 Bansal A, Goyal S, Goyal A, Jana M. WHO classification of soft tissue tumours 2020: an update and simplified approach for radiologists. Eur J Radiol 2021; 143: 109937
• 4 Noebauer-Huhmann I-M, Vanhoenacker FM, Vilanova JC. et al. Soft tissue tumor imaging in adults: European Society of Musculoskeletal Radiology-Guidelines 2023-overview, and primary local imaging: how and where?. Eur Radiol 2024; 34 (07) 4427-4437
• 5 Teh J. Ultrasound of soft tissue masses of the hand. J Ultrason 2012; 12 (51) 381-401
• 6 Hung EHY, Griffith JF, Yip SWY. et al. Accuracy of ultrasound in the characterization of superficial soft tissue tumors: a prospective study. Skeletal Radiol 2020; 49 (06) 883-892
• 7 Hayes AJ, Nixon IF, Strauss DC. et al. UK guidelines for the management of soft tissue sarcomas. Br J Cancer 2025; 132 (01) 11-31
• 8 Pertea M, Lunca S, Filip A. et al. Atypical sites of the lipoma on the hand and fingers: clinical and imaging features and surgical outcomes. Diagnostics (Basel) 2022; 12 (10) 2286
• 9 Mavrogenis AF, Panagopoulos GN, Angelini A. et al. Tumors of the hand. Eur J Orthop Surg Traumatol 2017; 27 (06) 747-762
• 10 Kransdorf MJ. Benign soft-tissue tumors in a large referral population: distribution of specific diagnoses by age, sex, and location. AJR Am J Roentgenol 1995; 164 (02) 395-402
• 11 Tripoli M, Cordova A, Moschella F. Characteristics, management techniques, and outcomes of the most common soft-tissue hand tumors: a literature review and our experience. Ann Plast Surg 2017; 79 (06) 558-565
• 12 Evans HL. Atypical lipomatous tumor, its variants, and its combined forms: a study of 61 cases, with a minimum follow-up of 10 years. Am J Surg Pathol 2007; 31 (01) 1-14
• 13 Moran LM, Li Cai CY, Ramirez A, Royuela A. Differentiation of atypical lipomatous tumors from lipomas: our experience with visual analysis of conventional magnetic resonance imaging. J Imaging 2025; 11 (02) 47
• 14 Tfayli Y, Baydoun A, Naja AS, Saghieh S. Management of myxoid liposarcoma of the extremity. Oncol Lett 2021; 22 (02) 596
• 15 Boyd CJ, Davis C, Kurapati S, Ananthasekar S, Andino DMA, Kilic A. Recurrent myxoid liposarcoma of the hand. Radiol Case Rep 2019; 15 (02) 150-153
• 16 Agarwal S, Haase SC. Lipofibromatous hamartoma of the median nerve. J Hand Surg Am 2013; 38 (02) 392-397 ; quiz 397
• 17 Sirinoglu H, Sönmez A, Sav A, Numanoglu A. Lipofibromatous hamartoma of the median nerve. Ann Plast Surg 2010; 65 (02) 174-176
• 18 Elbayer AM, Alharami S, Elhessy AH. Lipofibromatous hamartoma of the median nerve: a case report. Cureus 2023; 15 (01) e33516
• 19 Morris G, Jacobson JA, Kalume Brigido M, Gaetke-Udager K, Yablon CM, Dong Q. Ultrasound features of palmar fibromatosis or Dupuytren contracture. J Ultrasound Med 2019; 38 (02) 387-392
• 20 Reyntiens P, Vanhoenacker FM, Jager T. Tardigrade and manifold sign: two new signs in Dupuytren's disease. Semin Musculoskelet Radiol 2023; 27 (03) 381-392
• 21 Yacoe ME, Bergman AG, Ladd AL, Hellman BH. Dupuytren's contracture: MR imaging findings and correlation between MR signal intensity and cellularity of lesions. AJR Am J Roentgenol 1993; 160 (04) 813-817
• 22 Farzaliyev F, Steinau H-U, Ring A. et al. Classic type of epithelioid sarcoma of the distal upper extremity: clinical and oncological characteristics. Hand (N Y) 2023; 18 (06) 1037-1043
• 23 Martin-Broto J, Mondaza-Hernandez JL, Moura DS, Hindi N. A comprehensive review on solitary fibrous tumor: new insights for new horizons. Cancers (Basel) 2021; 13 (12) 2913
• 24 Zhang R, Yang Y, Hu C. et al. Comprehensive analysis reveals potential therapeutic targets and an integrated risk stratification model for solitary fibrous tumors. Nat Commun 2023; 14 (01) 7479
• 25 Demicco EG, Wagner MJ, Maki RG. et al. Risk assessment in solitary fibrous tumors: validation and refinement of a risk stratification model. Mod Pathol 2017; 30 (10) 1433-1442
• 26 Hyodo R, Komada T, Takada A. et al. Solitary fibrous tumors in the extremities: imaging findings for six patients. Nagoya J Med Sci 2015; 77 (1-2): 167-178
• 27 Çevik HB, Kayahan S, Eceviz E, Gümüştaş SA. Tenosynovial giant cell tumor in the hand: experience with 173 cases. J Hand Surg Asian Pac Vol 2020; 25 (02) 158-163
• 28 Stacy GS, Bonham J, Chang A, Thomas S. Soft-tissue tumors of the hand: imaging features. Can Assoc Radiol J 2020; 71 (02) 161-173
• 29 Kolisetty PV, Ali SS, Ahmad I, Sudhy IK, Prakash O, Kishore YR. Giant cell tumor of the tendon sheath of the hand: analysis of factors impacting recurrence. Indian J Plast Surg 2024; 57 (02) 123-128
• 30 Michailidis A, Tsifountoudis I, Kitridis D, Karagergou E, Givissis A, Givissis P. Role of MRI and surgical excision in long-standing diffuse-type GCTTS of the flexor tendon sheath. Radiol Case Rep 2024; 20 (03) 1368-1373
• 31 Wang C, Song R-R, Kuang P-D, Wang L-H, Zhang M-M. Giant cell tumor of the tendon sheath: magnetic resonance imaging findings in 38 patients. Oncol Lett 2017; 13 (06) 4459-4462
• 32 Morey VM, Garg B, Kotwal PP. Glomus tumours of the hand: review of literature. J Clin Orthop Trauma 2016; 7 (04) 286-291
• 33 Glazebrook KN, Laundre BJ, Schiefer TK, Inwards CY. Imaging features of glomus tumors. Skeletal Radiol 2011; 40 (07) 855-862
• 34 Hazani R, Houle JM, Kasdan ML, Wilhelmi BJ. Glomus tumors of the hand. Eplasty 2008; 8: e48
• 35 Yanai K, Tajika T, Kuboi T. et al. A case of solitary digital glomus tumor associated with neurofibromatosis type 1. SAGE Open Med Case Rep 2023; 11: X231193984
• 36 Zhou H-Y, Jiang S, Ma F-X, Lu H. Peripheral nerve tumors of the hand: clinical features, diagnosis, and treatment. World J Clin Cases 2020; 8 (21) 5086-5098
• 37 Crist J, Hodge JR, Frick M. et al. Magnetic resonance imaging appearance of schwannomas from head to toe: a pictorial review. J Clin Imaging Sci 2017; 7: 38
• 38 Forthman CL, Blazar PE. Nerve tumors of the hand and upper extremity. Hand Clin 2004; 20 (03) 233-242 , v
• 39 Winter N, Dohrn MF, Wittlinger J, Loizides A, Gruber H, Grimm A. Role of high-resolution ultrasound in detection and monitoring of peripheral nerve tumor burden in neurofibromatosis in children. Childs Nerv Syst 2020; 36 (10) 2427-2432
• 40 Beert E, Brems H, Daniëls B. et al. Atypical neurofibromas in neurofibromatosis type 1 are premalignant tumors. Genes Chromosomes Cancer 2011; 50 (12) 1021-1032
• 41 Behrens J, Ho DSK, Frojo G, Tadisina KK, Kraemer BA. Neurofibromas on the hands. Eplasty 2018; 18: ic8
• 42 Wasa J, Nishida Y, Tsukushi S. et al. MRI features in the differentiation of malignant peripheral nerve sheath tumors and neurofibromas. AJR Am J Roentgenol 2010; 194 (06) 1568-1574
• 43 Shirodkar K, Hussein M, Reddy PS. et al. Imaging of peripheral intraneural tumors: a comprehensive review for radiologists. Cancers (Basel) 2025; 17 (02) 246
• 44 Yang H, Dong Y, Wang Z. et al. Traumatic neuromas of peripheral nerves: diagnosis, management and future perspectives. Front Neurol 2023; 13: 1039529
• 45 Debs P, Luna R, Fayad LM, Ahlawat S. MRI features of benign peripheral nerve sheath tumors: how do sporadic and syndromic tumors differ?. Skeletal Radiol 2024; 53 (04) 709-723
• 46 Blay JY, von Mehren M, Jones RL. et al. Synovial sarcoma: characteristics, challenges, and evolving therapeutic strategies. ESMO Open 2023; 8 (05) 101618
• 47 Cho EB, Lee SK, Kim JY, Kim Y. Synovial sarcoma in the extremity: diversity of imaging features for diagnosis and prognosis. Cancers (Basel) 2023; 15 (19) 4860
• 48 Lazerges C. Soft tissue sarcomas of the forearm, wrist and hand. Hand Surg Rehabil 2017; 36 (04) 233-243
• 49 Chotel F, Unnithan A, Chandrasekar CR, Parot R, Jeys L, Grimer RJ. Variability in the presentation of synovial sarcoma in children: a plea for greater awareness. J Bone Joint Surg Br 2008; 90: 1090-1096
• 50 Boubcheur M, Ben Salah S, Najib A. Incidental discovery of melanoma metastasis in the thenar compartment: a case report. Cureus 2025; 17 (02) e79405
• 51 Afshar A, Farhadnia P, Khalkhali H. Metastases to the hand and wrist: an analysis of 221 cases. J Hand Surg Am 2014; 39 (05) 923-32.e17
• 52 Cattelan M, Dumontier C. Metastatic tumour of the hand—three new cases and a literature review. J Plast Reconstr Aesthet Surg 2021; 74 (09) 2163-2168
• 53 Lee J, Sinno H, Tahiri Y, Gilardino MS. Treatment options for cutaneous pyogenic granulomas: a review. J Plast Reconstr Aesthet Surg 2011; 64 (09) 1216-1220
• 54 Koo MG, Lee SH, Han SE. Pyogenic granuloma: a retrospective analysis of cases treated over a 10-year period. Arch Craniofac Surg 2017; 18 (01) 16-20
• 55 Jing W, Wen X, Zhang M, Zhou C, Huang J, He Y. Ultrasonographic features of an intravascular lobular capillary hemangioma originating in the basilic vein: case report and literature review. J Clin Ultrasound 2021; 49 (07) 741-745
• 56 Punjwani S, Jani C, Liu W. et al. Burden of gout among different WHO regions, 1990–2019: estimates from the global burden of disease study. Sci Rep 2024; 14 (01) 15953
• 57 Klauser AS, Halpern EJ, Strobl S. et al. Gout of hand and wrist: the value of US as compared with DECT. Eur Radiol 2018; 28 (10) 4174-4181
• 58 Fukuda T, Subramanian M, Noda K. et al. The comprehensive role of dual-energy CT in gout as an advanced diagnostic innovation. Skeletal Radiol 2024 December 17 (Epub ahead of print)
• 59 Davies J, Riede P, van Langevelde K, Teh J. Recent developments in advanced imaging in gout. Ther Adv Musculoskelet Dis 2019; 11: X19844429
• 60 Bulbin B, Kramer N, Rosenstein ED, Rosenstein RK. JAK inhibitors for the treatment of rheumatoid nodules. JAAD Case Rep 2025; 59: 113-116
• 61 Nalbant S, Corominas H, Hsu B, Chen LX, Schumacher HR, Kitumnuaypong T. Ultrasonography for assessment of subcutaneous nodules. J Rheumatol 2003; 30 (06) 1191-1195
• 62 Starok M, Eilenberg SS, Resnick D. Rheumatoid nodules: MRI characteristics. Clin Imaging 1998; 22 (03) 216-219

Publication History

Article published online:
03 December 2025