Composite mycosis fungoides and B-cell chronic lymphocytic leukemia.

Concordant or composite mycosis fungoides and B-cell chronic lymphocytic leukemia (B-CLL) is exceedingly rare, with only 10 cases previously described to our knowledge. We report a case of a 64-year-old woman who developed generalized erythroderma 5 years after the diagnosis of early stage B-CLL. Over the next 6 years of her clinical course multiple sequential samples of skin, peripheral blood, and one enlarged lymph node were studied in detail by flow cytometry, immunohistochemistry, molecular diagnostics, and electron microscopy. The progressive cutaneous infiltrates were initially characterized as leukemia cutis, infiltration by B-CLL. Three years later, when she developed worsening skin disease and lymphadenopathy, the cutaneous infiltrates were characterized as cutaneous T-cell lymphoma. At that point, a biopsy of an enlarged lymph node revealed a composite lymphoma of both B-CLL and cutaneous T-cell lymphoma, and the peripheral blood also contained circulating cells of both neoplasms. Herein we summarize the literature on concordant cutaneous T-cell lymphoma and B-CLL, and the literature on concordant T- and B-cell neoplasms in general, with a review of the postulated relationships between these neoplasms.