RCPA Examinations in Anatomical pathology - Questions ... - Rcpa.tv

Case 8: Female 35 – enlarging
painful soft tissue mass in left foot
• MICROSCOPIC
• There is a tumour present within a tendon or aponeurosis with adjacent skeletal muscle. The
tumour shows central necrosis. The viable tumour consists of cells with large vesicular nuclei,
prominent nucleoli and a moderate amount of eccentrically located d eosinophilic cytoplasm
arranged in nests separated by fibrous septa. Focally there is streaming of cells within nests.
The tumour is well circumscribed but not encapsulated. Mitotic figures are present.
• Comment
• The histologic appearance is that of a soft tissue malignant tumour. The location of the tumour
and the histology would favour a clear cell sarcoma of tendon and d aponeurosis with a differential
diagnosis which includes metastatic melanoma, synovial sarcoma, epitheloid sarcoma, malignant
peripheral nerve sheath tumour and metastatic carcinoma.
• Investigations
• Cytogenetic for characteristic t(12;22) of clear cell sarcoma
• Immunoperoxidase stains: S100, HMB45, Leu7, NSE– positive in clear cell sarcoma .
• Keratin, EMA, CD99, Bcl2 – positive in synovial sarcoma
• CAM5.2, EMA, vimentin, , CD34 – positive in epitheloid sarcoma
• S100 – variable positive in malignant peripheral nerve sheath tumour
• AE1/AE3, CK5/6, CAM5.2 – positive in carcinoma
• SUMMARY
• Left foot: Clear cell sarcoma of tendon and aponeurosis