Chromosome studies in mycosis fungoides

G-banded chromosome analysis was performed on peripheral blood lymphocytes after phytohaemagglutinin stimulation from sixteen patients with mycosis fungoides. A number of chromosome abnormalities were observed in a low proportion of blood lymphocytes in seven patients in later stages of the disease. In four patients similar marker chromosomes in multiple copies were present, some of them without a clearly visible centromere. We conclude that a correlation exists between the presence of chromosome abnormalities in circulating blood lymphocytes and the course of the disease.