Flow cytometric DNA analysis of malignant fibrous histiocytoma and related fibrohistiocytic tumors.

Fibrohistiocytic neoplasms with similar histologic characteristics may have vastly different biologic behaviors. We studied 23 fibrohistiocytic tumors to determine if cellular DNA content was correlated with clinical outcome. Archival paraffin blocks of 9 malignant fibrous histiocytomas (MFH), 3 dermatofibrosarcoma protuberans, 9 dermatofibromas, 1 juvenile xanthogranuloma, and 1 nodular fasciitis were processed, stained with propidium iodide, and analyzed by flow cytometry. Five of 9 (56%) MFH and 1 of 3 (33%) dermatofibrosarcoma protuberans were aneuploid. All 11 benign fibrohistiocytic tumors were diploid. Local recurrence occurred in 3 of 5 (60%) cases of aneuploid MFH, but in none with a diploid MFH tumor. No cases of dermatofibrosarcoma protuberans or benign tumors recurred. Aneuploidy was associated with decreased survival, as 2 of 5 patients with aneuploid MFH died within 1 year of diagnosis whereas all 4 patients with diploid MFH tumors are alive after an average follow-up of 4 years (range, 1 to 11). The diploid and aneuploid groups did not differ in clinical stage at the time of diagnosis. Our results indicate that retrospective DNA analysis can detect aneuploidy in both MFH as well as other fibrohistiocytic tumors, and that aneuploidy in MFH may place the patient at increased risk for local recurrence and mortality.