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Cutaneous Lymphoma at a Glance
  • Second most common group of extranodal lymphomas; estimated annual incidence is 1 in 100,000.
  • Clonal proliferations of neoplastic T or B lymphocytes, and rarely of natural killer cells or plasmacytoid dendritic cells, arising in mid and late adulthood.
  • Clinical behavior and prognosis are completely different from those of histologically similar systemic lymphomas.
  • Most common form of cutaneous lymphoma is mycosis fungoides (MF), a cutaneous T-cell lymphoma, which is categorized as patch, plaque, or tumor stage. Related features include severe pruritus, alopecia, palmoplantar hyperkeratosis, and bacterial superinfection
  • Histologically the patch/plaque stage of MF is characterized by an epidermotropic band-like infiltrate of neoplastic T lymphocytes with hyperconvoluted cerebriform nuclei involving the upper dermis variably with exocytosis and formation of intraepidermal Pautrier's microabscesses. The tumor stage consists of a dermal nodular infiltrate sparing the epidermis.

Cutaneous lymphomas (CLs) represent clonal proliferations of neoplastic T or B lymphocytes and rarely of natural killer (NK) cells or—for historical reasons— plasmacytoid dendritic cells. CLs have been recognized as a heterogeneous group with distinct variability in clinical presentation, histopathology, immunophenotyping, and prognosis.

Primary CLs often show a completely different clinical behavior and prognosis than do histologically similar systemic lymphomas, which may involve the skin secondarily. Therefore, primary CLs require different approaches to treatment. For this reason, a consensus classification has been created based on both the European Organisation for Research and Treatment of Cancer (EORTC) classification for primary CLs and the World Health Organization (WHO) classification for tumors of hematopoietic and lymphoid tissues. This first common classification (WHO-EORTC)1 categorizes the entities according to lineage and then according to a combination of morphology, immunophenotype, genetic features, and clinical syndromes (Box 145-1) and constituted the basis for the classification of CLs in the new WHO classification 2008.2 This chapter discusses the most frequent cutaneous T-cell lymphomas (CTCLs)—mycosis fungoides (MF), Sézary syndrome (SS), primary cutaneous anaplastic large-cell lymphoma (cALCL), and lymphomatoid papulosis (LyP)—and the most frequent cutaneous B-cell lymphomas (CBCLs)—primary cutaneous follicle center lymphoma (PCFCL), primary cutaneous marginal zone lymphoma (PCMZL), and primary cutaneous diffuse large B-cell lymphoma (PCLBCL), leg type. These seven types of cutaneous lymphoma represent nearly 90% of all CLs.3 Rare entities occurring primarily in the skin are also described.

Box 145-1 WHO-EORTC Classification of Primary Cutaneous Lymphomas

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