Primary cutaneous lymphomas are rare, accounting for 2% of all lymphomas. About 75% are T-cell lymphomas.
There are two major subgroups within the cutaneous T-cell lymphomas (CTCL) spectrum: mycosis fungoides (MF) and Sézary syndrome (SS).
MF is the prototype of CTCL. It is defined as a peripheral, epidermotropic non-Hodgkin’s T-cell lymphoma of low-grade malignancy, typically presenting in the skin initially, and proceeding in clinical progression from patches to plaques and tumors.
MF exhibits distinct histological (except in early stages), phenotypic, and genotypic features.
SS is a distinct variant of CTCL, characterized by exfoliative erythroderma, lymphadenopathy, lymphocytosis, pruritus, circulating Sézary cells, and a poor prognosis.
Primary cutaneous lymphoma is staged with the American Joint Committee on Cancer and the International Union against Cancer (AJCC/UICC) tumor, node, and metastasis (TNM) grouping and staging classification (7th edn.).
MF usually responds to skin-directed therapy first, with systemic treatments reserved for refractory, recurrent, or advanced disease. SS may respond to skindirected or systemic therapies.