An Infrequent Subcutaneous Nodule: Pediatric Angiomatoid Fibrous Histiocytoma

Abstract

Angiomatoid fibrous histiocytoma (AFH) is a rare pediatric soft-tissue tumor of intermediate malignancy, often misdiagnosed because of its resemblance to benign and malignant lesions. We report a 6-year-old child with a slowly enlarging subcutaneous nodule on the right forearm. Initial biopsy showed small, round cells positive for cluster differentiation 99. Complete excision revealed a circumscribed mesenchymal tumor with angiomatoid cavities and fibrous pseudocapsule. Immunohistochemistry and molecular studies confirmed AFH and excluded Ewing sarcoma. The patient remains disease-free after complete excision; prognosis is generally favorable with surgical management and long-term follow-up. This case highlights the diagnostic challenge of AFH and the importance of a comprehensive clinical, histological, immunohistochemical, and molecular analysis to avoid misdiagnosis.