Angiomatoid Fibrous Histiocytoma Mimicking a Hemangioma: A Case Report

Abstract

 Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor with intermediate malignant potential. We present a 5-year-old boy with AFH mimicking a hemangioma. He had a slowly growing subcutaneous tumor on his upper arm for 2 years. Ultrasonography showed the tumor had a rich blood flow, and hemangioma was suspected. The patient had no systemic symptoms, but blood tests showed elevated inflammatory responses and increased levels of interleukin-6, vascular endothelial growth factor, and immunoglobulins. Castleman disease was suspected, and the tumor was resected. Pathological examination revealed the presence of the EWSR1-CREB1 fusion gene. He was diagnosed with AFH. Hyperinflammation improved rapidly after tumor resection. AFH is a soft tissue tumor with few metastases and low mortality; however, it is often misdiagnosed and there is no established cure. Our findings suggest a diagnosis of AFH should be considered in cases of blood flow-rich subcutaneous masses with hypercytokinemia.