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A spectrum of cutaneous lymphoproliferative diseases: Primary cutaneous anaplastic large cell lymphoma (C-ALCL); Lymphomatoid papulosis; borderline lesions in which a definite distinction between C-ALCL and lymphomatoid papulosis cannot be made. A spectrum of related conditions originating from transformed or activated CD30+ T lymphocytes. Distinction of C-ALCL from systemic ALCL with cutaneous involvement is important. This is part of the Primary cutaneous CD30 positive T-cell lymphoproliferative disorders WHO group, which also includes lymphomatoid papulosis (see 9718/1).
Primary cutaneous anaplastic large cell lymphoma (C-ALCL) is one of two primary cutaneous CD30-positive T-cell lymphoproliferative disorders. (The other disorder, lymphomatoid papulosis [9718/1], is not reportable for cases diagnosed in 2010 and forward.) C-ALCL most frequently affects the skin of the trunk, face, extremities, and buttocks. Most patients present with solitary or localized nodules or tumors, and sometimes papules, and often show ulceration. Multifocal lesions are seen in about 20% of cases. These lymphomas frequently relapse in the skin. Extracutaneous dissemination occurs in <10% of the patients and mainly involves the lymph nodes. The prognosis is usually favorable with a 10-year disease-related survival of approximately 90%.
Definitive Diagnostic Methods
T-cell receptor (TCR) genes are clonally rearranged