Prepared by Dr. Erhan OKAY
Synovial sarcoma is a high-grade malignant soft tissue tumor primarily affecting the extremities of young adults. Diagnosis requires MRI, histopathology, and molecular confirmation of the SS18–SSX fusion gene. Treatment is multidisciplinary, centered on complete surgical excision with limb preservation when feasible, combined with perioperative radiotherapy and chemotherapy for large, deep, or high-risk lesions. Prognosis depends on tumor size, depth, margin status, and recurrence, with lung metastasis being the most common pattern of spread. Long-term surveillance is essential due to the potential for late metastatic relapse.
Epidemiology
Synovial sarcoma is a high-grade soft tissue sarcoma predominantly affecting adolescents and young adults, most commonly arising in the extremities, especially the lower limbs. The median age at diagnosis is in the 30s, with a slight male predominance. Diagnostic delays are common, with up to 35% of cases initially undergoing unplanned excision before referral to specialized centers (Broida 2024). The lungs are the most frequent site of metastasis (≈70%), followed by bone (10–20%) and lymph nodes (17%) (Wu 2017).
Diagnosis & Imaging
Diagnosis relies on a combination of MRI, histopathology, and molecular testing. Core needle biopsy with immunohistochemistry and fusion testing (SS18–SSX) should be performed at a sarcoma center before any surgery.
Pathology
Histologically, synovial sarcoma presents as monophasic, biphasic, or poorly differentiated forms, the latter associated with worse prognosis.
Immunoprofile: Bcl-2, EMA, and TLE1 are commonly positive (Li 2024).
Molecular confirmation via SS18–SSX gene fusion testing is diagnostic, particularly when morphology or IHC is inconclusive (Amary 2007).
Treatment Overview
Optimal management requires multimodal therapy within a specialized multidisciplinary team.
Prognosis
Prognosis depends on tumor size, depth, margin status, bone invasion, mitotic count, and recurrence. Adverse factors include tumor >5 cm, deep location, positive margins, axial site, and local relapse (Song 2017, Broida 2024). Late metastases (>5 years) are not uncommon; therefore, long-term surveillance is essential. Early re-excision with negative margins and appropriate perioperative therapy significantly improves metastasis-free and disease-specific survival.
References
