Diagnostic and prognostic evaluation of phenotypic markers TRAF1, MUM1, BCL2 and CD15 in cutaneous CD30-positive lymphoproliferative disorders

Background CD30 is expressed in various types of cutaneous lymphomas, including lymphomatoid papulosis (LyP), primary cutaneous anaplastic large cell lymphoma (C-ALCL), some cases of mycosis fungoides showing large cell transformation (MF-TR) and skin localizations of systemic anaplastic lymphoma kinase (ALK)-positive or ALK-negative ALCL. Differentiation between these entities is often not possible on the basis of histology alone, but several markers, including TRAF1, MUM1 and BCL2, have been reported to provide additional diagnostic information. Objective To evaluate the diagnostic and prognostic significance of these markers in a large group of cutaneous CD30-positive lymphoproliferations. Methods An immunohistochemical study on the expression of TRAF1, MUM1, BCL2 and CD15 was performed on skin biopsies from 28 patients with C-ALCL, 39 patients with LyP, 11 patients with CD30-positive MF-TR, two with ALK-positive ALCL and six with ALK-negative ALCL. In addition, the prognostic significance of these markers was evaluated. Results TRAF1 was expressed in roughly 70-80% and MUM1 was expressed in 70-100% of all the groups of cutaneous CD30-positive lymphoproliferations. Highest levels of BCL2 were expressed in MF-TR (73%), in contrast to 21% in C-ALCL and 36% in LyP. Highest levels of CD15 were expressed in C-ALCL (43%), compared with 18% in LyP and 9% in MF-TR. A relationship with survival was not clear. Conclusions The results of the present study suggest that TRAF1, MUM1, BCL2 and CD15 cannot be considered as useful diagnostic or prognostic marker in cutaneous CD30-positive lymphoproliferations. Differentiation between these different conditions should be based on a combination of clinical, histological and immunophenotypical criteria.