Angiomatoid Fibrous Histiocytoma, A Great Mimicker -A Short Series of 3 Cases with EWSR1 Fusion

Angiomatoid Fibrous histiocytoma (AFH) is a rare soft tissue neoplasm that is often misdiagnosed initially. It is commonly encountered in the superficial extremities of children and young adults. It is composed of a nodular proliferation of bland looking spindled to ovoid cells, some with variant histology and characterized by EWSR1 fusion. We, herein, present three such cases, who presented with swelling in the right leg (case 1), right forearm (case 2), and right thigh (case 3). Case 2 presented in the fourth decade with a large swelling compared to the other two cases that presented in 3rd decade with a small swelling. Histologic examination of case 2 showed extensive myxoid changes making it diagnostically challenging. All three cases showed EWSR1 fusion with a break-apart probe. Follow-up was uneventful in all three cases. AFH, although it is a benign neoplasm, is a great mimicker of various low-grade spindle cell sarcomas. Awareness of this entity with its various histomorphological variants is necessary to accurately diagnose this lesion.