DNA flow cytometry from paraffin-embedded tissue in diagnosis of cutaneous malignant lymphomas and pseudolymphomas.

DNA content and cell cycle distributions in paraffin-embedded blocks of 111 skin biopsy specimens of 70 patients with cutaneous malignant lymphomas (CML) and 41 patients with cutaneous pseudolymphomas (CPL) including chronic actinic dermatitis (CAD) were estimated by DNA flow cytometry. A statistical significant difference between DNA indices (DIs) or proliferative indices (PIs) for CML including mycosis fungoides (MF) II, MF III, Sezary's syndrome (SS), cutaneous peripheral T-cell lymphomas other than MF and SS, cutaneous germinal center cell-derived lymphomas and cutaneous genuine histiocytic lymphoma from CPL. DIs were also helpful in differentiating MF I from CPL. There was a linear relationship between DIs and PIs, both of which had a parallel relationship to the degrees of malignancy and mortality of varieties of CML. The finding of aneuploidy is likely to be useful in differentiating CML from CPL. It is worth noting that DIs, PIs and proportions of aneuploidy in CAD were all higher than those of higher malignancy of CML. These data could not be considered as markers of malignancy.