Epidemiology
A rare sarcoma of adolescents and young adults, classically found in the hand, forearm, or distal tissues. It can look like a chronic skin or tendon lesion in the hand or forearm, which delays diagnosis if it is not biopsied.
Basic features
It can look like a wound, a nodule, or a benign granuloma and tends to spread to the lymph nodes; the diagnosis is supported by loss of INI1/SMARCB1 expression on the biopsy, a characteristic feature.
Usual treatment
It requires wide resection, lymph node evaluation, and radiotherapy or systemic therapy depending on the stage; in advanced disease with loss of INI1/SMARCB1 there is an approved targeted therapy (tazemetostat, an EZH2 inhibitor).
Outcomes and prognosis
It carries a high risk of local recurrence and of lymph node and lung metastasis; the prognosis worsens over time because of its tendency to recur, so it needs close follow-up.