Alveolar Soft Part Sarcoma: Imaging Evaluation

Abstract

This case report concerns a 16-year-old boy who developed pain in his right thigh after a soccer game. Imaging studies revealed a pathologic transtrochanteric fracture of the right femur, accompanied by a large expansive intramuscular lesion centered in the deep planes of the adductor musculature. Main imaging findings included intense enhancement and vascularization of the lesion, along with peripheral and central flow voids, the latter described as characteristic of this subtype of soft tissue sarcoma. Alveolar soft part sarcoma is a rare and distinctive sarcoma with an indolent clinical course that typically occurs in young patients and predominantly affects the deep tissues of the lower limbs.

Key Points

• Soft tissue sarcomas are a rare group of malignancies, often found in the extremities. Suspicious features include larger size, deeper location, heterogeneous enhancement, and progressive growth.

• Alveolar soft part sarcoma (ASPS), a rare subtype primarily seen in children, is characterized by high T1 signal intensity, intense contrast enhancement, and more than five central and peripheral flow voids that are highly indicative of this condition.

• Magnetic resonance imaging (MRI) is the preferred modality for evaluating these lesions. Advanced MRI techniques, such as diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC), enhance diagnostic confidence, particularly in postoperative evaluations.

Keywords

alveolar soft part sarcoma - soft tissue sarcoma - magnetic resonance imaging

Publication History

Article published online:
31 March 2025

• References

• 1 Porrino J, Al-Dasuqi K, Irshaid L. et al. Update of pediatric soft tissue tumors with review of conventional MRI appearance-part 1: tumor-like lesions, adipocytic tumors, fibroblastic and myofibroblastic tumors, and perivascular tumors. Skeletal Radiol 2022; 51 (03) 477-504
• 2 Maloney E, Al-Dasuqi K, Irshaid L. et al. Update of pediatric soft tissue tumors with review of conventional MRI appearance-part 2: vascular lesions, fibrohistiocytic tumors, muscle tumors, peripheral nerve sheath tumors, tumors of uncertain differentiation, and undifferentiated small round cell sarcomas. Skeletal Radiol 2022; 51 (04) 701-725
• 3 Wright A, Desai M, Bolan CW. et al. Extraskeletal Ewing sarcoma from head to toe: multimodality imaging review. Radiographics 2022; 42 (04) 1145-1160
• 4 Vibhakar AM, Cassels JA, Botchu R, Rennie WJ, Shah A. Imaging update on soft tissue sarcoma. J Clin Orthop Trauma 2021; 22: 101568
• 5 Dangoor A, Seddon B, Gerrand C, Grimer R, Whelan J, Judson I. UK guidelines for the management of soft tissue sarcomas. Clin Sarcoma Res 2016; 6 (01) 20
• 6 Aga P, Singh R, Parihar A, Parashari U. Imaging spectrum in soft tissue sarcomas. Indian J Surg Oncol 2011; 2 (04) 271-279
• 7 Lee SK, Jee WH, Jung CK, Chung YG. Multiparametric quantitative analysis of tumor perfusion and diffusion with 3T MRI: differentiation between benign and malignant soft tissue tumors. Br J Radiol 2020; 93 (1115) 20191035
• 8 Imaizumi S, Morita T, Ogose A. et al. Soft tissue sarcoma mimicking chronic hematoma: value of magnetic resonance imaging in differential diagnosis. J Orthop Sci 2002; 7 (01) 33-37
• 9 Harish S, Lee JC, Ahmad M, Saifuddin A. Soft tissue masses with “cyst-like” appearance on MR imaging: distinction of benign and malignant lesions. Eur Radiol 2006; 16 (12) 2652-2660
• 10 Garcia del Muro X, de Alava E, Artigas V. et al; Spanish Group for Research on Sarcoma. Clinical practice guidelines for the diagnosis and treatment of patients with soft tissue sarcoma by the Spanish group for research in sarcomas (GEIS). Cancer Chemother Pharmacol 2016; 77 (01) 133-146
• 11 Lee JH, Kim Y, Yoo HJ, Kim HS, Cho HS, Han I. Prognoses of superficial soft tissue sarcoma: the importance of fascia-tumor relationship on MRI. Eur J Surg Oncol 2020; 46 (02) 282-287
• 12 Jo VY, Fletcher CDM. WHO classification of soft tissue tumours: an update based on the 2013 (4th) edition. Pathology 2014; 46 (02) 95-104
• 13 Ferrari A, Sultan I, Huang TT. et al. Soft tissue sarcoma across the age spectrum: a population-based study from the Surveillance Epidemiology and End Results database. Pediatr Blood Cancer 2011; 57 (06) 943-949
• 14 Folpe AL, Deyrup AT. Alveolar soft-part sarcoma: a review and update. J Clin Pathol 2006; 59 (11) 1127-1132
• 15 Fujiwara T, Kunisada T, Nakata E. et al. Advances in treatment of alveolar soft part sarcoma: an updated review. Jpn J Clin Oncol 2023; 53 (11) 1009-1018
• 16 O'Sullivan Coyne G, Naqash AR, Sankaran H, Chen AP. Advances in the management of alveolar soft part sarcoma. Curr Probl Cancer 2021; 45 (04) 100775
• 17 Chang X, Li Y, Xue X, Zhou H, Hou L. The current management of alveolar soft part sarcomas. Medicine (Baltimore) 2021; 100 (31) e26805
• 18 Crombé A, Brisse HJ, Ledoux P. et al. Alveolar soft-part sarcoma: can MRI help discriminating from other soft-tissue tumors? A study of the French sarcoma group. Eur Radiol 2019; 29 (06) 3170-3182
• 19 Zarrin-Khameh N, Kaye KS. Alveolar soft part sarcoma. Arch Pathol Lab Med 2007; 131 (03) 488-491
• 20 Pang LJ, Chang B, Zou H. et al. Alveolar soft part sarcoma: a bimarker diagnostic strategy using TFE3 immunoassay and ASPL-TFE3 fusion transcripts in paraffin-embedded tumor tissues. Diagn Mol Pathol 2008; 17 (04) 245-252
• 21 Suh JS, Cho J, Lee SH. et al. Alveolar soft part sarcoma: MR and angiographic findings. Skeletal Radiol 2000; 29 (12) 680-689
• 22 Kato H, Kanematsu M, Mizuta K. et al. “Flow-void” sign at MR imaging: a rare finding of extracranial head and neck schwannomas. J Magn Reson Imaging 2010; 31 (03) 703-705
• 23 Robbin MR, Murphey MD, Temple HT, Kransdorf MJ, Choi JJ. Imaging of musculoskeletal fibromatosis. Radiographics 2001; 21 (03) 585-600