Fatal Rocky Mountain spotted fever. Hematologic and lymphoreticular observations.

Generalized histiocytic proliferation with a component of phagocytosis and thrombocytopenia accompanies a number of infectious diseases and malignant neoplasms. Its extent and occurrence were studied in the hematopoietic and lymphoreticular tissues of fatal childhood cases of Rocky Mountain spotted fever. Its frequent occurrence and morphologic similarities to other associated causes were documented.