Benign fibrous histiocytoma of the skin with potential for local recurrence: a tumor to be distinguished from dermatofibroma.

We studied eight patients with benign fibrous histiocytoma (BFH) of the skin that differed, morphologically and biologically, from ordinary dermatofibroma (DF) and compared their tumors with a consecutive series of 141 DF. The patients ranged in age from 13 to 49 yr. Their lesions consisted of cutaneous nodules, 2 cm or less in size, that had been present for less than 1 yr. Seven were located on an extremity. Three of six patients (50%) who could be followed had recurrences 2, 5, and 8 mo following excision of their tumors. Microscopically, seven of the eight cutaneous BFH (CBFH) involved both dermis and subcutis. Five were distinctly multinodular. Subcutaneous involvement and/or multinodularity were present in each case. Fibroblastic and histiocytic cells were arranged in a monotonous storiform pattern throughout most or all of each lesion. There was moderate nuclear variability, but pleomorphism was absent. Several of the tumors contained sparse inflammatory, multinucleate, and foam cells and hemosiderin deposits. Vascularity was prominent. We believe that the multinodular architecture of CBFH and its involvement of both dermis and subcutis usually allow distinction from DF. The latter is uninodular, centered in the dermis, and exhibits only minor subcutaneous extension. Most DF lack the diffuse, well developed storiform appearance of CBFH. Local recurrence further distinguishes CBFH from DF, which rarely recurs. Rather than representing an aberrant form of DF, the clinical and microscopic features of CBFH suggest that it is closely related to, if not identical with, BFH of other tissues and organs.