Desmoplastic fibroblastoma. A report of seven cases.

Seven cases of desmoplastic fibroblastoma, a distinctive fibrous soft-tissue tumor, are presented. The patients, four men and three women, ranged in age from 25 to 83 years (median 57 years). The tumors were located in the neck (two cases), the upper arm, the forearm, the shoulder, the lateral thigh, and the dorsum of the foot (one case each). Three neoplasms were intramuscular, and four were subcutaneous (two of the latter were directly on top of muscle). Maximum tumor dimension varied from 1.8 cm to 9 cm (median 3.2 cm). Grossly, the lesions were well circumscribed, firm, and white to gray to tan on cut section. Microscopically, they were composed of medium-sized to large "reactive appearing" spindled to stellate fibroblasts sparsely distributed in a fibromyxoid to densely fibrous background; mitotic figures were very rare or absent, tumor necrosis was not seen, and vascularity was low. The tumor border was generally well de-limited, although interdigitation with adjacent muscle or fat was present in areas in some cases. Follow-up ranging from 15 months to 46 months (median 28 months) after excision was available on five patients. No recurrences were observed.