Primary cutaneous lymphomas comprise a prognostically heterogeneous group of lymphocytic skin neoplasms, which display a broad spectrum of clinical, histologic, immunophenotypic, and genetic features. The histopathological examination plays an essential role and is often the starting point in the diagnostic workup of cutaneous lymphomas. In most cases, the histopathological and the phenotypic analysis alone are limited to provide a list of differential diagnoses. As a consequence of overlapping clinical, histologic, phenotypic, and genetic features among several entities of cutaneous lymphomas, the clinicopathological correlation is of utmost importance to achieve the final diagnosis.
Key points
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Clinicopathologic correlation is an essential element in the diagnostic approach to cutaneous lymphomas.
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Cutaneous lymphomas show overlapping histologic and immunophenotypic features, but can differ significantly in their course and prognosis.
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Monoclonality does not necessarily indicate malignancy. Lack of monoclonality does not exclude the diagnosis of cutaneous lymphoma.
Introduction
Primary cutaneous lymphomas (CLs) comprise a heterogeneous group of lymphocytic neoplasms with a broad spectrum of clinical, histologic, immunophenotypical, and genetic features ( Box 1 ). The histopathological examination plays an essential role and is often the starting point in the diagnostic workup of CLs. The classification of CLs follows the current World Health Organization (WHO) classification (4th edition, 2008), which is widely accepted by hematopathologists and dermatopathologists. The WHO classification of the tumors of hematopoietic and lymphoid tissues follows the multiparameter approach by defining lymphomas according to their clinical, histopathological, immunophenotypic, and genetic features as well as the side of primary manifestation, which was originally introduced by the Revised European-American Lymphoma classification (REAL).
MATURE T-CELL AND NK-CELL NEOPLASMS
Mycosis fungoides (MF)
MF variants and subtypes:
Folliculotropic MF
Pagetoid reticulosis
Granulomatous slack skin
Sézary syndrome
Adult T-cell leukemia/lymphoma
Primary cutaneous CD30+ T-cell lymphoproliferative disorders
Primary cutaneous anaplastic large cell lymphoma
Lymphomatoid papulosis
Subcutaneous panniculitis-like T-cell lymphoma
Extranodal NK-/T-cell lymphoma, nasal type
Primary cutaneous peripheral T-cell lymphoma
Rare subtypes:
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Primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma (provisional)
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Primary cutaneous γ/δ T-cell lymphoma
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Primary cutaneous CD4+ small/medium T-cell lymphoma (provisional entity)
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Primary cutaneous peripheral T-cell lymphoma, unspecified
MATURE B-CELL NEOPLASMS
Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma)
Primary cutaneous follicle center lymphoma
Diffuse large B-cell lymphoma, NOS
Primary cutaneous diffuse large B-cell lymphoma, leg type
Primary cutaneous diffuse large B-cell lymphoma, others
Intravascular large B-cell lymphoma
Note: This list is mainly limited to cutaneous lymphomas in the WHO classification.
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Hematopoietic Stem Cell Transplant for Mycosis Fungoides and Sézary Syndrome
Practical Management of CD30 +Lymphoproliferative Disorders
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