Imaging Characteristics of Angiomatoid Fibrous Histiocytoma: A Case Report and the Diagnostic Challenges in Differentiating Fluid–Fluid Level Soft Tissue Lesions

Abstract

Angiomatoid fibrous histiocytoma (AFH) is a rare mesenchymal tumor. Due to its non-specific clinical and radiologic features, AFH is often misdiagnosed as other soft tissue lesions. We report the case of a 10-year-old boy who presented with a painless mass in the gluteal region. Initial ultrasound and Magnetic Resonance Imaging (MRI) suggested a hemorrhagic lesion with fluid–fluid levels. Despite two inconclusive percutaneous biopsies, the patient underwent wide local excision, and histopathological examination confirmed the diagnosis of AFH. This case highlights the diagnostic challenges of AFH and underscores the importance of recognizing its imaging characteristics—particularly in distinguishing it from other soft tissue lesions that also exhibit fluid–fluid levels on MRI—in the appropriate clinical context.