Nonsecretory plasma cell dyscrasia followed by acute granulocytic leukemia 25 years after Thorotrast administration.

Twenty-three years after an injection of Thorotrast, profound depression of humoral and cellular immunity associated with extensive marrow plasmocytosis developed in a man aged 75 years. Twelve months of chemotherapy with L-phenylalanine mustard, resulted in hematologic remission. Radioautograph of his marrow showed signs of alpha-radiation; whole body counting revealed a significant thorium burden. One year after chemotherapy was stopped, and two years after initial presentation, aleukemic acute granulocytic leukemia led to his death. The role of thorium in the etiology of possibly two successive hematopoietic neoplasms is discussed.