Application of DNA flow cytometry from paraffin‐embedded tissue to the diagnosis of mycosis fungoides

The distinction of mycosis fungoides from benign inflammatory lesions is sometimes difficult by conventional histological techniques. Aneuploidy, a feature often associated with malignant tumors, can be assessed even in tissue routinely processed in paraffin using the flow cytometric technique of Hedley and associates. In many tumor systems, there are significant diploid clones. We have evaluated the flow cytometric DNA ploidy of paraffin‐embedded tissue in the diagnosis and prognosis of mycosis fungoides (MF). We studied 22 cases of MF and 10 control cases of inflammatory skin lesions with epidermal involvement. Aneuploidy was found in 27% of the MF cases, but in none of the controls (ED). Aneuploid features were seen in 23% of tissues from early stage disease. Aneuploidy did not correlate with atypia, epidermotropism, or number of mitoses. There was a trend towards showing adverse outcome in those patients with aneuploid lesions. The detection of aneuploidy might be helpful for early diagnosis of MF.