Evaluation of the 2008 World Health Organization classification for non-mycosis fungoides, non-Sezary syndrome T/NK-cell lymphomas with primary cutaneous involvement

Backgroun: Cutaneous non-mycosis fungoides non-Sezary syndrome T/NK cell lymphomas (non-MF/non-SS CTCL) are rare. In 2005, a consensus of the World Health Organization (WHO) and European Organization for Research and Treatment of Cancer (EORTC) classifications for primary cutaneous lymphomas was established. These guidelines were then adopted into the WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues, 2008. This study aims to assess the applicability of the WHO 2008 classification in a retrospective series of CTCL cases registered in a reference academic center in Brazil. Methods: Twenty-seven patients with non-MF/non-SS CTCL were studied. Clinical, histopathological and immunophenotypical features based on an extensive panel of antibodies were applied to classify the cases according to the WHO, 2008. Results: Overall, diagnostic categories included eight (29.6%) cutaneous anaplastic large-cell lymphoma, five (18.5%) lymphomatoid papulosis, six (22.2%) extranodal natural killer (NK)/T-cell lymphoma, nasal type, five (18.5%) adult T-cell leukemia/lymphoma, one (3.7%) cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma and two (7.4%) of peripheral T-cell lymphoma not otherwise specified (NOS). Conclusions: The WHO classification (2008) was applicable to most cases of non-MF/non-SS CTCL, while some cases remained unclassified and were considered NOS-peripheral T-cell lymphoma. An unexpected high frequency of NK/T-cell lymphoma nasal type was observed.