Poikilodermatous mycosis fungoides and atrophic large-plaque parapsoriasis exhibit similar abnormalities of T-cell antigen expression.

We studied the immunohistologic findings of skin biopsy specimens from 21 patients with poikiloderma (14 with mycosis fungoides [MF] and seven with atrophic large-plaque parapsoriasis [ALPP]). Both types of poikiloderma were similar with regard to T-cell antigen expression. In each case, most T cells expressed the CD4+ (helper/inducer) phenotype and lacked Leu-8 antigen. T cells were also deficient in Leu-9 antigen in most cases (MF, 11/14 [79%]; ALPP, 4/7 [57%]). These T-cell antigen deficiencies are similar to those described previously in various types of MF and indicate that such deficiencies are common in minimally infiltrated, patch-stage MF lesions. Because combined Leu-8/Leu-9 antigen deficiencies are uncommon in inflammatory skin diseases, our findings are consistent with the view that ALPP is an early form of MF, as had been suggested previously by results of clinicopathologic studies.