1. Opportunity to study the pathologic changes in ruptured spleen of acute vivax malaria was afforded by splenectomy.
2. Subcapsular hematoma precedes rupture.
3. The capsular tear is an obvious consequence of the changes in the spleen occurring in acute malaria. Small hemorrhages occur in the vicinity of the capsule or deep in the tissues.
4. A rapidly enlarging spleen with underlying vascular alteration predisposes to rupture. Minimal trauma may be a precipitating element.
5. Diffuse cellular hyperplasia, subintimal and adventitial leukopoiesis, dilated sinuses and occasional thrombosis and infarction constitute the characteristic pattern in malaria.
6. Changes in the left lung base may serve as a diagnostic aid in cases in which the diagnosis of splenic rupture is considered.