Malignant Fibrohisticytoma of the Knee in a Patient with HIV.

This case report describes a patient presenting with anterior knee pain (extensor mechanism pain), a poorly studied complaint in the HIV population. The final diagnosis was malignant fibrohistiocytoma, a rare condition among knee pathologies, successfully treated with endoprosthesis after tumor resection. This article focuses on what the authors learned after treating this patient, particularly on the difficulty in making a correct diagnosis of this group of patients due to lack of adequate epidemiological characterization.