Karyotype studies of cutaneous T cell lymphoma: evidence for clonal origin.

Neoplastic lymphocytes from 3 patients with widespread cutaneous T cell lymphoma were karyotyped, using a chromosome banding technique. None of the patients had previously received chemotherapy. Morphologically homogeneous populations of abnormal T cells were available from 2 distinct body regions of 2 of the individuals and from the bone marrow of the third. Karyotypes from each of the 3 patients indicated monoclonality of their lymphoma. These observations suggest that extracutaneous dissemination of cutaneous T cell lymphoma involves spread of neoplastic cells derived from a single clone. If future studies can demonstrate that those neoplastic T cells actually localized in the skin are also progeny of a single malignant cell, a widely accepted concept that cutaneous T cell lymphoma is of multifocal origin will have to be reexamined.