The Diagnosis of Disseminated Histoplasmosis from Marrow Aspiration

Abstract

The diagnosis of histoplasmosis is based on the visualization of typical intracellular organisms in various body tissues or from culture material. Histoplasmosis is essentially a reticuloendothelial disease with the Histoplasma capsulatum organisms localizing in the reticulum cells. A granulomatous process is usually provoked, and both granulomas and scattered reticulendothelial cells containg the typical fungi may be found in the marrow. The bone marrow is frequently infected, particularly in the disseminated form of the disease, and a high incidence of positive bone marrow cultures has been reported. Although the organisms have been described in bone marrow smears, little emphasis has been given to the use of direct marrow examinations as a simple and rapid means of diagnosing histoplasmosis, whereas marrow cultures have been frequently employed. Three cases of disseminated histoplasmosis in whom the organisms were found in bone marrow smears are described. One had chronic lymphocytic leukemia, another diabetes mellitus, and the third had no other disease. The frequent confusion of disseminated histoplasmosis with leukemias and lymphomas as well as the tendency of histoplasmosis to complicate these disorders is discussed. It is proposed that whereas bone marrow cultures may give a higher incidence of positive results, direct examination of smears prepared at the time the marrow is aspirated for culture should be done routinely for early diagnosis of histoplasmosis.