IMMUNOPHENOTYPING AND T-CELL RECEPTOR-GAMMA GENE REARRANGEMENT ANALYSIS AS AN ADJUNCT TO THE HISTOPATHOLOGIC DIAGNOSIS OF MYCOSIS-FUNGOIDES

Background: The histopathologic diagnosis of mycosis fungoides (MF) ma y be difficult. Objective: Our purpose was to evaluate the role of imm unophenotyping and T-cell receptor (TCR) gene rearrangement studies as an adjunct to the histopathologic diagnosis of MF. Methods: Immunohis tochemical studies with antibodies to CD4, CD5, CD7, and CD8 and TCR g amma gene rearrangement analysis with a polymerase chain reaction were performed on fresh-frozen material of patients with ''classic'' histo logy of Tuff ''inconclusive'' histology, and benign inflammatory derma toses. Results: Clonal TCR gamma gene rearrangements were found in 11 of 16 (69%) of classic MF cases, in 3 of 19 (16%) of inconclusive case s, and in none of the 12 inflammatory dermatoses cases (P < .05 and P < .001, respectively). Only the mean CD7 counts were statistically sig nificantly different between these 3 groups (MF < inconclusive < infla mmatory). Conclusion: Inconclusive histology is probably a heterogeneo us group in which CD7 counts and TCR gamma gene rearrangement studies might help to differentiate the MF cases from the benign cases.