Rare variants of cutaneous T-cell lymphoma

Besides the classical forms of cutaneous T-cell lymphoma (C-CTCL), such as mycosis fungoides and Sezary's syndrome, unique variants may be encountered. The classification of these rare cutaneous T cell lymphomas is problematic and controversial. Newer classifications of lymphoma in general, such as the Revised European-American Lymphoma (REAL) Classification, emphasize well-established clinico-pathological entities. It seems appropriate to attempt to bring greater clarity to the classification of cutaneous T-cell lymphomas using the same principles. In this review, we list and characterize the rare variants of cutaneous T-cell lymphoma, such as (1) clinical, histological and immunological variants of mycosis fungoides; (2) progressive cutaneous T-cell lymphoma (P-CTCL) including transformed classical cutaneous T-cell lymphoma (TC-CTCL) and primary progressive cutaneous T-cell lymphoma (PP-CTCL); (3) angiocentric and angioimmunoblastic cutaneous T-cell lymphomas; (4) large cell anaplastic, CD30(+) T-cell lymphoma; (5) HTLV-I-associated adult T-cell leukemia/lymphoma (ATLL); (6) manifestations of primary extracutaneous T-cell neoplasias; (7) unclassifiable cutaneous T-cell lymphoma.