Fine-needle aspiration of primary and recurrent benign fibrous histiocytoma: Classic, aneurysmal, and myxoid variants

There is a limited number of correlative cytopathological studies of fibrous histiocytoma (FHC). To better define cytopathological criteria of diagnosis, we have reviewed fine‐needle aspirates (FNA) from 36 FHCs (32 classical, 1 myxoid, and 3 aneurysmal variants on corresponding histological sections). Original cytological diagnoses were benign in 33 (91.7%) cases (22 accurate) and false positive in 3 (8.3%) cases. All smears were surprisingly homogenous and composed of histiocytic cells with finely vacuolated cytoplasm in 27 (75%) cases, small regular spindle cells in 25 (69%) cases, and giant cells in 17 (47%) cases. Histiocytic cells were attached to vascular structures in 9 (25%) cases. Slight cytonuclear atypia was seen in five (14%) cases. Three (8.3%) cases showed numerous siderophages. In two (5.6%) cases, there were abundant inflammatory backgrounds and in one (3%) case there was a scant myxoid background. Storiform patterns, round cells, prominent atypia, necroses, or mitotic figures were not seen. FHC should be differentiated from other benign, low‐ and intermediate‐grade spindle‐cell neoplasms such as low‐grade fibrosarcoma, dermatofibrosarcoma protuberans, nodular fasciitis, spindle‐cell malignant melanoma, and monophasic synovial sarcoma. Some cases may be misinterpreted as malignant, especially in cases of recurrence or in patients with a cancer history. Diagn. Cytopathol. 2004;31:387–391. © 2004 Wiley‐Liss, Inc.