Angiomatoid fibrous histiocytoma with paraneoplastic platelet storage pool deficiency

Angiomatoid fibrous histiocytoma is a rare soft tissue tumor usually discovered in young individuals. This tumor is often mistaken for a hematoma and typically misdiagnosed. It is commonly found in the extremities and may be associated with a site of recent or previous trauma. Characteristic histology includes nodules of histiocytoid spindle cells with pseudoangiomatoid spaces, fibrous pseudocapsules, and lymphoid cuffing. We describe the case of an 8-year-old girl who presented after incision and drainage of a superficial thigh lesion and experienced subsequent chronic bleeding of her wound. Her initial presentation was concerning for an underlying bleeding disorder, and laboratory analysis uncovered a paraneoplastic platelet function disorder that resolved with therapy of the primary tumor.