(also aplastic anemia), a disease of the blood system in which there occurs irreversible wasting of the bone marrow, development of fatty tissue in the bone-marrow cavities, and abrupt inhibition of hematopoiesis.

Panmyelophthisis may result from chemical poisoning with benzene and its derivatives or with tetraethyl lead, from the biological effect of ionizing radiation, or from other factors. In most cases the cause of the disease is not clear. The total suppression of hematopoiesis in panmyelophthisis is caused by a disruption in the synthesis of deoxyribonucleic acid in the blood-producing cells. This leads to disruption in the reproduction and maturation of the cells. Also significant is the disruption of the humoral regulation of hematopoiesis.

The symptoms of panmyelophthisis are a decrease in the number of erythrocytes, leukocytes, and thrombocytes, with infectious complications and hemorrhaging; absence of signs of blood regeneration; and a significant increase in the erythrocyte sedimentation rate. The disease may be acute or chronic. Methods of treatment are blood transfusions, hormone therapy, hemostatics, and antibiotics. In severe cases the spleen is removed and donor bone marrow is transplanted.