Immunophenotyping and T-cell receptor gamma gene rearrangement analysis as an adjunct to the histopathologic diagnosis of mycosis fungoides.

Abstract

The histopathologic diagnosis of mycosis fungoides (MF) may be difficult. Our purpose was to evaluate the role of immunophenotyping and T-cell receptor (TCR) gene rearrangement studies as an adjunct to the histopathologic diagnosis of MF. Immunohistochemical studies with antibodies to CD4, CD5, CD7, and CD8 and TCR gamma gene rearrangement analysis with a polymerase chain reaction were performed on fresh-frozen material of patients with "classic" histology of MF, "inconclusive" histology, and benign inflammatory dermatoses. Clonal TCR gamma gene rearrangements were found in 11 of 16 (69%) of classic MF cases, in 3 of 19 (16%) of inconclusive cases, and in none of the 12 inflammatory dermatoses cases (P < .05 and P < .001, respectively). Only the mean CD7 counts were statistically significantly different between these 3 groups (MF < inconclusive < inflammatory). Inconclusive histology is probably a heterogeneous group in which CD7 counts and TCR gamma gene rearrangement studies might help to differentiate the MF cases from the benign cases.