A 23-year-old young man presents with pain in his left calf. A physical examination detects a mass in the calf area.
Correct answer: B - Monophasic synovial sarcoma
Synovial sarcoma is a malignancy of the mesenchymal neoplasm, more commonly seen in soft tissues. Morphologically, there are two important variants: the monophasic variant in which the tumor is composed essentially of a malignant spindle cell proliferation, and the biphasic variant in which similar spindle proliferation also alternates with glandular component, thus the term biphasic synovial sarcoma. Synovial sarcoma commonly shows focal positive staining with epithelial markers, such as keratin or epithelial membrane antigen, in addition to other markers including TLE, vimentin, Bcl-2, and CD99. However, these tumors have a specific translocation (X;18), (SYT-SSX) by molecular analysis that can be detected in about 80-90% of these cases. These tumors commonly follow an aggressive behavior with metastatic disease.