T-cell receptor-gamma gene analysis in evolving to advancing cutaneous T-cell lymphoma

The diagnosis of cutaneous T-cell lymphoma is often a challenge for the dermatopathologist. Early stages can mimic inflammatory dermatoses. Our aim was to explore the applicability of a standard T-cell receptor-gamma polymerase chain reaction in various subtypes of cutaneous T-cell lymphomas. Ninety-six biopsy specimens from 38 patients were selected. These included 72 specimens of mycosis fungoides, 12 specimens of non-mycosis fungoides T-cell lymphomas, and 12 specimens in which histology was non-specific or equivocal in patients who were later diagnosed to have lymphoma. T-cell clones were detected in 53 of 72 specimens of mycosis fungoides and eight of 12 specimens of non-mycosis fungoides lymphomas. Of the 72 specimens of mycosis fungoides, T-cell clones were detected in eight of 10 specimens of mycosis fungoides-associated follicular mucinosis and pigmented purpura-like mycosis fungoides. Four specimens from the 12 prediagnostic for cutaneous T-cell lymphomas showed presence of T-cell clones, identical to subsequent clones detected when lymphoma was fully established. In specimens where histology is not diagnostic and T-cell receptor-gamma gene analysis is positive, patients should be followed up closely. T-cell receptor-gamma gene analysis is a useful adjunct to histological diagnosis of early stage and variant types of mycosis fungoides.