Flow-cytometric DNA analysis in cutaneous fibrohistiocytic tumors

BACKGROUND: Fibrohistiocytic tumors are rare skin tumors. There are many kinds of fibrohistiocytic tumors. It is often difficult to differentiate dermatofibrosarcoma protuberans (DFSP) and malignant fibrous histiocytoma (MFH) from dermatofibroma (DF) and other benign tumors. OBJECTIVE: In this study, the possible usefulness of DNA ploidy for the differentiation was studied. METHODS: Five MFH, 9 DFSP, 3 DF, 2 lipofibromas and 2 scars were studied for DNA ploidy using a flow cytometer. RESULTS: All the 7 benign tumors showed a diploid pattern. Of 14 malignant fibrohistiocytic tumors, 8 cases (57.1%) showed an aneuploid and 6 a diploid pattern. Two of 5 MFH (40.0%) and 6 of 9 DFSP (66.7%) showed an aneuploid pattern. These results showed that fibrohistiocytic tumors with an aneuploid pattern are malignant, though those with a diploid pattern may be benign or malignant. CONCLUSION: Analysis of DNA ploidy using flow cytometry was concluded to be useful for the differentiation of malignant fibrohistiocytic tumors from benign ones.