Lymphomatoid papulosis and cutaneous CD30+ lymphoma.

Lymphomatoid papulosis and cutaneous CD30+ lymphoma are closely related conditions in which large atypical lymphocytes that have similar immunophenotypic features occur. In lymphomatoid papulosis, the lesions are papules and nodules that spontaneously involute. There are two polar histologic patterns, type A and B, in which the large atypical cells resemble those of Hodgkin's disease and mycosis fungoides, respectively, but in many cases, features of both types are present, either separately or in the same lesions. Variants of lymphomatoid papulosis include cases with a perifollicular distribution and those with lymphocytic vasculitis or dermal mucin deposits. Clinical lesions that tend to be stable, a monomorphous cellular composition, and in the case of immunocompromised patients, the presence of Epstein-Barr viral genome characterize cutaneous CD30+ lymphoma. A loss of response to transforming growth factor-beta, which normally dampens cellular proliferation, may differentiate CD30+ lymphoma from lymphomatoid papulosis.