A Study of Aplastic Anemia in an Autopsy Series With Special Reference to Atomic Bomb Survivors in Hiroshima and Nagasaki

A study of the occurrence of aplastic anemia among atomic bomb survivors in Nagasaki and Hiroshima, Japan was made from a review of a series of 6327 autopsies from 1949 to June 1967 and the late effects of ionizing radiation were evaluated. There were 340 cases reviewed independently by a team of hematologists and pathologists. Of the 45 cases documented as aplastic anemia, 42 were definite and three were probable. Six additional cases were classified as probable. The cases were grouped into four categories depending upon the distance of the subject from the hypocenter at the time of the bomb (ATB). All patients fulfilled the requirement clinically of having pancytopenia. Bone marrow findings at autopsy from various sites revealed aplastic or hypocellular changes in 77.3%. The etiology in 42 cases was idiopathic, one case was drug-induced, one case received radiation for carcinoma of the cervix, and one case congenital in origin. No difference was noted in the exposed cases from the nonexposed. Of those who were exposed to 10 or more rad, the majority (four of five) died prior to 1955. On the basis of the data presented, there is no definite morphologic evidence that implicates ionizing radiation in the pathogenesis of aplastic anemia as a delayed complication of exposure in the A-bomb survivors.