Keywords
image-guided biopsy - occipital bone - breast cancer
Introduction
Breast cancer metastasis to the occipital condyle is a rare phenomenon that poses challenges in both diagnosis and treatment. Skull base metastases, including those affecting the occipital condyle, are infrequent, with various syndromes identified based on the anatomical involvement of the lesion.[1]
[2]
[3] The occipital condyle syndrome (OCS) consists of intense occipital headaches and hypoglossal nerve palsies.
The typical diagnostic approach for occipital condyle lesions involves magnetic resonance imaging (MRI) studies. Early radiotherapy can offer pain relief and enhance the patient's quality of life. Occipital biopsies are rarely reported, although surgical techniques have been described.[4]
[5]
[6] Percutaneous radiological transoral biopsies have also been documented.[7]
[8]
A recent study by Betting et al provided a comprehensive review of skull base and calvarium biopsies utilizing computed tomography (CT) scan guidance.[9] Here, we propose a simple and secure method for performing biopsies of the occipital condyle using CT scan guidance.
Case Report
A 43-year-old woman presented to the emergency department with persistent occipital neuralgia. A head MRI was conducted, revealing a lytic mass on the left occipital condyle. Additionally, a positron emission tomography-fluorodeoxyglucose scan highlighted high metabolic activity of this occipital lesion, along with a small hypermetabolic lesion in the breast ([Fig. 1]). The overall picture was of a small breast cancer, potentially metastatic to bone.
Fig. 1 (A) T2-weighted axial head magnetic resonance imaging (MRI). (B) Positron emission tomography-fluorodeoxyglucose (PET-FDG) axial head computed tomography (CT). (C, D) Unenhanced head CT scan, brain and bone windows.
Following consultation by a multidisciplinary committee, it was decided to proceed with a CT-guided biopsy to ascertain whether the occipital condyle lesion originated from breast cancer, rendering it metastatic and thus changing the treatment (lororegional vs. systemic). The differential diagnosis of this lytic lesion was plasmacytoma.
The biopsy procedure was performed under CT guidance and general anesthesia, with the patient positioned in prone position. Utilizing a posterior ascending approach, a 13-gauge, 10-cm bone biopsy needle (Osteo-site needle, IziMedical, United States) was inserted, ensuring avoidance of the vertebral artery as determined by the previous diagnostic angio-CT. Early contact with occipital bone ensured continued avoidance of the vertebral artery. Subsequently, upon entering the condyle bone cortex, soft tissue sampling was conducted using an 18-gauge, 15-cm needle (Temno, Merit Medical, United States) ([Fig. 2]).
Fig. 2 (A) Double oblique axial unenhanced computed tomography (CT) scan displaying the biopsy path. (B) Double oblique sagittal unenhanced CT with preoperative angio-CT fusion illustrating the vertebral artery (white arrow).
Two samples, each measuring 2 cm in length, were obtained and sent for pathology analysis. Following the procedure, a head CT scan without contrast was performed, revealing no signs of bleeding. A neurological examination conducted 3 hours postbiopsy showed normal findings, and the patient was discharged on the first day following the operation. Subsequent pathology confirmed the presence of breast carcinoma at the biopsy site.
Discussion
Skull base metastases are uncommon and pose challenges in diagnosis due to the difficulty in obtaining a histopathologic confirmation. Lesions affecting the occipital condyle can present with various symptoms, constituting the rare OCS, which is characterized by occipital headaches and ipsilateral 12th nerve palsy.[1]
[2]
[3]
Several surgical approaches have been described, including the far lateral, transoral transclival, and minimally invasive tubular approaches, each requiring different levels of neurosurgical expertise and carrying potential complications due to their invasive nature.[4]
[5]
[6]
A few radiological minimally invasive approaches have been reported, such as the transoral approach,[7]
[8]
[10] and one study described various percutaneous CT-guided biopsies of the skull base.[9]
Preoperative angio-CT is essential to identify the vertebral artery between C0 and C1, and the preoperative CT scan path must be strictly followed. Early contact with the occipital bone ensures avoidance of the vertebral artery. The use of a breakable Chiba-type needle can enhance the safety of the biopsy path. This posterior ascending approach is deemed safe and straightforward for diagnosing occipital condyle lesions, utilizing conventional biopsy needles and without any complications.
Conclusion
In summary, the posterior ascending occipital condyle approach is proven to be both straightforward and safe for conducting bone biopsies. This technique, as demonstrated in our case of breast carcinoma metastasis, provides an effective means of obtaining tissue samples for accurate diagnosis and treatment planning. Its reliability and ease of execution make it a valuable tool in managing patients with occipital condyle lesions, offering potential improvements in patient care and outcomes.
