Epithelioid Sarcoma Presenting in the Thumb of a Child.

Epithelioid sarcoma (ES) is a high-grade, soft tissue tumor of mesenchymal origin that rarely occurs in children and is often misdiagnosed as a benign entity. We present the case of a 12-year-old girl with a delayed diagnosis of ES of the left thumb. Radiological examination showed possible calcinosis from inflammation or traumatic injury. However, histopathological and immunohistochemistry studies showed findings consistent with a diagnosis of ES. She was treated with amputation of the interphalangeal joint of the left thumb. This case highlights the clinical and pathologic correlation required for the appropriate diagnosis and treatment of patients with soft tissue masses.