The expression of activation/proliferation antigens (CD 25, CD 30, Ki 67, transferrin receptor) in lymph nodes and skin were compared in nine patients with mycosis fungoides (MF) with patients with erythroderma not related to MF, and patients with reactive lymphofollicular hyperplasias (a total of 14 patients). A panel of differentiation antigens was analyzed in addition. Reactivities were revealed by the APAAP technique. Activation/proliferation antigen scores in lymph nodes were related to the clinical stages of MF in most instances (low scores in cases of MF stage I/II, high scores in 3/4 cases of MF stage III/IV). They differed markedly in cases of non-MF-erythrodermia with the exception of one patient, and in all cases of reactive lymphofollicular hyperplasia. Expression of activation/proliferation antigens in lymph nodes were different in most cases from those in skin and peripheral blood. For diagnostic use, the activation/proliferation antigen scores were superior to the cell differentiation antigen profiles. Among cellular differentiation antigens, only the extent of CD1+ cells provided some diagnostic information, since the number of these cells were markedly increased in all cases of dermatopathic lymphadenitis with/without MF when compared with reactive lymphofollicular hyperplasia. In the diagnosis of MF, immunohistochemistry of activation/proliferation or differentiation antigens cannot replace routine paraffin histology, but may provide supplement any data in equivocal cases.
