The significance of MUM1/IRF4 protein expression and IRF4 translocation of CD30(+) cutaneous T-cell lymphoproliferative disorders: a study of 53 cases.

Current laboratory technics, clinicopathologic findings cannot always reliably distinguish primary cutaneous CD30(+) lymphoproliferative disorders (LPD), such as lymphomatoid papulosis (LyP), primary cutaneous CD30(+) anaplastic large cell lymphoma (PCALCL), transformed mycosis fungoides (T-MF) and systemic ALK(-) anaplastic large cell lymphoma (ALCL) with skin involvement. We investigated the presence of IRF4 translocation with break apart DNA-FISH method of these entities according to the recent studies of Feldman et al. In our study group with 53 cases, the detection of IRF4 translocation had a specificity and positive predictive value for PCALCL of 100%. In contrast MUM1/IRF4 protein expression was distributed widely without any predictive value.