Clinicopathological features of angiomatoid fibrous histiocytoma: a series of 21 cases with variant morphology.

We analyzed the clinicopathological features of angiomatoid fibrous histiocytoma (AFH) in 21 cases with emphasis on variant morphology. In our series, ten patients were male and eleven were female. The patients' mean age was 26.9 years old. Tumors were located on the lower limbs in eight cases, upper limbs in three, trunk in five, head and neck in four, and trachea in one. Microscopically, thirteen cases were characterized by typical AFH. Tumor cells showed marked tumor pleomorphism with giant hyperchromatic nuclei in two cases. Mitotic figures (2-3/10HPF) were found in two cases. Focal necrosis was found in one case. A number of multinucleated giant cells were found in two cases. Two cases showed obvious myxoid change in the stromal. Prominent sclerosing changes in the stromal component were found in two cases. Immunohistochemistry staining showed tumor cells were positive for EMA, desmin, and CD68. Five cases demonstrated the presence of rearrangement of the EWSR1 gene by FISH detection. Only two patients had tumor recurrence at 3 and 6 months after tumor resection, respectively. In conclusion, AFH has variant histological patterns. The differential diagnosis includes inflammatory myofibroblastic tumor, aneurysmal fibrous histiocytoma, follicular dendritic cell tumor, and metastatic tumor of lymph node.