Primary cutaneous lymphoma: An overview based on the WHO–EORTC classification

Primary cutaneous lymphomas, defined by their presentation in the skin in the absence of extracutaneous disease at diagnosis, are a heterogenous group of T- and B-cell neoplasms. The commonest, mycosis fungoides, has no nodal counterpart but others show morphological, immunophenotypic and genotypic similarities to primary extracutaneous lymphomas and yet display very different clinical behaviour. This review discusses the salient features of the major entities in the context of the recent World Health Organization/European Organization for the Research and Treatment of Cancer (WHO/EORTC) classification of primary cutaneous lymphoma. In particular, it emphasizes the importance of close clinicopathological correlation and detailed immunophenotyping in their diagnosis.