Primary cutaneous lymphomas represent distinct clinical and histopathologic subtypes of extranodal lymphomas. They can be defined as neoplasms of the immune system, characterized by a proliferation of either T, natural killer (NK), or B lymphocytes, which show a particular tropism for the skin. By definition, primary cutaneous lymphomas show no evidence of extracutaneous manifestations at presentation.

Primary cutaneous lymphomas should be separated from secondary skin manifestations of extracutaneous (usually nodal) lymphomas and leukemias, which represent metastatic disease characterized by a worse prognosis and requiring different treatments. Since the histopathology of primary and secondary cutaneous lymphomas may be similar or identical, in many cases complete staging investigations are needed to establish this distinction (early mycosis fungoides representing the most important, but not the only exception to this rule).

Besides cutaneous lymphomas, many diseases that simulate them either clinically, histopathologically, or both, are a daily source of diagnostic problems (cutaneous pseudolymphomas). Criteria for diagnosis and differential diagnosis of these benign lymphoproliferative conditions are discussed in Chapter 26 in this book.

Classification of Cutaneous Lymphomas

The World Health Organization (WHO) published in 2008 the last revision of the Classification of Tumours of Haematopoietic and Lymphoid Tissues (Table 1.1) (as of 2014, an update is being prepared by an Advisory Committee) [1]. The WHO scheme is used worldwide, and replaced all former classification systems (older readers will still remember the plethora of different classifications that were used in the past, representing the source of huge problems when comparing data from different centers). For what concerns cutaneous lymphomas, the WHO scheme is based on the seminal work made by the European Organization for Research and Treatment of Cancer (EORTC) – Cutaneous Lymphomas Task Force, that in 1997 published the first comprehensive classification of cutaneous lymphomas [2], subsequently revised together with a WHO panel in 2005 (Table 1.2) [3]. A comparison of the 2005 and 2008 schemes is provided in Table 1.3.

Cutaneous T-cell and NK-cell lymphomas
Mycosis fungoides (MF)
MF variants and subtypes
Folliculotropic MF
Pagetoid reticulosis
Granulomatous slack skin
Sézary syndrome
Adult T-cell leukemia/lymphoma
Primary cutaneous CD30+ 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, unspecified
Primary cutaneous aggressive epidermotropic CD8+ T-cell lymphoma (provisional)
Cutaneous γ/δ T-cell lymphoma (provisional)
Primary cutaneous CD4+ small/medium-sized pleomorphic T-cell lymphoma (provisional)
Cutaneous B-cell lymphomas
Primary cutaneous marginal zone B-cell lymphoma
Primary cutaneous follicle center lymphoma
Primary cutaneous diffuse large B-cell lymphoma, leg type
Primary cutaneous diffuse large B-cell lymphoma, other
Intravascular large B-cell lymphoma
Precursor hematologic neoplasm
CD4+/CD56+ Only gold members can continue reading. Log In or Register to continue Share this: Click to share on Twitter (Opens in new window) Click to share on Facebook (Opens in new window) Related Related posts: 17: Cutaneous Lymphomas in HIV-Infected Individuals 3: Sézary Syndrome 5: Subcutaneous Panniculitis-like T-cell Lymphoma 16: Cutaneous Post-transplant Lymphoproliferative Disorders 21: Blastic Plasmacytoid Dendritic Cell Neoplasm 11: Cutaneous Follicle Center Lymphoma Stay updated, free articles. Join our Telegram channel Join Tags: Skin Lymphoma Aug 7, 2016 | Posted by admin in Dermatology | Comments Off on 1: Introduction Full access? Get Clinical Tree Get Clinical Tree app for offline access Get Clinical Tree app for offline access