Aberrant immunophenotypes in mycosis fungoides.

Skin biopsy specimens from 40 patients with mycosis fungoides (MF) were examined by a selective procedure for the assessment of immunophenotypic deviation. In 19 cases (48%), aberrant phenotypes were detected. Type and degree of aberration differed greatly without apparent clinicopathologic correlation. Different phenotypes in the same patient occurring either simultaneously or during the course of the diseases were observed. Phenotypic aberration showed a statistically significant correlation with tumor stage MF, the large cerebriform tumor cell type, blast cell transformation, and diffuse dermal infiltration. In combination with longer-existing disease, more lymph node and visceral involvement and a higher mortality rate of MF in the aberrant group indicated an association with advanced disease. Its prognostic relevance for the individual patient, however, seemed limited because of the association of aberration and a long-lasting indolent course in many other patients. The assessment of phenotypic aberration formed a valuable contribution to the diagnosis of MF, especially in cases with little cellular atypia.