Non-mycosis fungoides cutaneous T-cell lymphoma: reclassification according to the WHO-EORTC classification

Non-mycosis fungoides (non-MF) primary cutaneous T-cell lymphomas (PCTCL) are heterogeneous and divided into subgroups by the World Health Organization-European Organization for Research and Treatment of Cancer (WHO-EORTC) classification of cutaneous lymphomas. We report the first North American series to examine the applicability of the classification, compare our findings with the predominant European literature and confirm the significance of separation into the indolent and aggressive groups.

Forty-four non-MF PCTCL cases with available tissue for phenotyping, adequate clinical staging information and follow-up were reclassified according to the WHO-EORTC classification.

Non-MF PCTCL had a longer overall survival (OS) (13.8 years) compared with secondary cutaneous T-cell lymphoma (SC-TCL) (2.5 years). Primary cutaneous anaplastic large cell lymphoma (PC-ALCL) had the most favorable outcome (OS 14.1 years), whereas secondary and primary peripheral T-cell lymphoma, unspecified had the shortest OS (2.5 and 2.4 years, respectively). Primary cutaneous CD4+ small/medium-sized pleomorphic T-cell lymphoma (CTLCD4) appeared to have a favorable course.

Most non-MF PCTCL can be classified according to the WHO-EORTC classification. The relative frequencies are similar to European experience. Non-MF PCTCL is a heterogeneous group with a favorable outcome compared to SC-TCL, especially PC-ALCL and CTLCD4. Separation of non-MF PCTCL into indolent and aggressive groups appears clinically significant and may provide direction for therapeutic decisions.