Abstract
A 76 year old man with mycosis fungoides developed an immunoblastic sarcoma and a leukemic blood picture in the final tumor stage after 6 years, in which the disease had clinically progressed in a typical manner. The results of histological and cytochemical studies of autopsy material are presented. Based on these findings and evidence of the T cell nature of mycosis fungoides, the immunoblastic sarcoma observed in the terminal stage of this case of mycosis fungoides might be of the rare T cell type.