Clinicopathological study of hematological disorders in Thorotrast administration in Japan

Ten leukemia group and four aplastic anemia cases were clinicopathologically studied in Thorotrast administered autopsies. The short period from the appearance of hematological symptom to death, the relatively low percentage of leukemic cells in the peripheral blood, the high frequency of erythroleukemia, i.e., 50% of leukemia group, and a case of atypical megakaryocyte proliferation were revealed in leukemia group patients. There was the tendency that leukemic cell infiltration in the spleen became slight or minimal with progression of its fibrosis. As a result, the degree of the spleen swelling was mild or lacking in leukemia group patients of Thorotrast administration. On the other hand, the findings such as hyperplastic or normoplastic bone marrow, an increase in immature granulocytic series or no decrease in the number of the megakaryocyte were observed in aplastic anemia cases. Thus, in hematological disorders of Thorotrast adminstered patients, both leukemia group and aplastic anemia cases were though to be mainly atypical type, and it was speculated that the damage by Thorotrast may act on the hematopoietic stem cell level, considering the appearance of abnormal trilineage hematopoietic cells and complex chromosome aberrations of the bone marrow cells. In addition, it was thought that the fibrosis of the bone marrow as well as the spleen was induced by Thorotrast deposition. (author)