High frequency of primary cutaneous lymphomas associated with lymphoproliferative disorders of different lineage.

In patients suffering from primary cutaneous lymphomas, secondary malignancies of various origin may develop. However, the frequency of a second neoplasm deriving from another lymphoid lineage is still unclear and may be underestimated. We screened all our patients with primary cutaneous lymphomas from a 4-year recruitment period for a coexisting secondary lymphoproliferative disorder. The cohort comprised of a total of 82 patients with primary cutaneous lymphomas, 62 with primary cutaneous T-cell lymphoma (CTCL), 18 with primary cutaneous B-cell lymphomas, and two with CD4+/CD56+ hematodermic neoplasm/blastic lymphomas. Seven patients (8.5%) were identified with a coexisting lymphoma of a different lymphoid lineage. Four patients with Sézary syndrome (SS) suffered from systemic B-cell lymphoma. Two of these developed SS after chemotherapy of their B-cell lymphoma. The other three patients with various types of skin lymphomas (SS, Mycosis fungoides [MF], primary cutaneous marginal zone lymphoma) developed Hodgkin's disease (hairy cell leukemia). Our data indicate that patients with primary cutaneous lymphomas have an elevated risk for the development of a secondary lymphoproliferative disorder even without previous chemotherapy. Possible explanations for this association include a genetic predisposition, alterations in early progenitor cells, underlying viral infections, and/or stimulation of a B-cell clone by the malignant helper T cells of the primary CTCL and vice versa.