Cutaneous T-lymphocyte lymphoma in association with multiple myeloma.

We report a case of cutaneous T-lymphocyte lymphoma in which multiple myeloma, a B-lymphocyte neoplasm, developed. We also review the emerging evidence on the immunoregulatory capacity of neoplastic T lymphocytes. Our case clinically supports the notion that neoplastic T lymphocytes may sometimes express helper activity for a specific B-lymphocyte clone (idiotype-specific helper function).