Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue neoplasm of intermediate malignant potential most commonly occurring in children in the subcutis of the limbs and trunk. This unusual tumour shows overlapping immunohistochemical and molecular findings with other soft tissue tumours which may result in diagnostic confusion with other benign and malignant entities, particularly when presenting at an uncommon site. We report a case of AFH involving the right mandible and adjacent soft tissue in a 78-year-old man. Typical histomorphological features were seen with a well-demarcated proliferation of sheets of syncytial histiocytoid to spindled cells with prominent interspersed blood-filled pseudocystic spaces. There was a surrounding dense lymphocytic inflammatory cuff. An incidental concomitant diagnosis of chronic lymphocytic lymphoma (CLL) was made which was involving the mandibular marrow and peritumoral inflammatory cuff. The AFH showed immunohistochemical expression of desmin, CD68 and CD99. ALK (D5F3) was strongly positive, presenting a potential diagnostic pitfall. The diagnosis of AFH was supported by fluorescence in situ hybridisation (FISH) evidence of an EWSR1 translocation. Our case serves as a typical example of AFH in an unusual location; to our knowledge it is the second case of AFH reported involving the mandible. The concomitant finding of CLL serves as a reminder to histopathologists to be alert for “dual diagnoses” when examining peritumoral inflammatory infiltrates.
Lee et al. (Sun,) studied this question.