Giemsa and Grocott in the recognition of Histoplasma capsulatum in blood smears

To facilitate the recognition of intracellular yeasts of Histoplasma capsulatum and differentiate it from Leishmania amastigotes and other parasites, using the combination of Giemsa and a rapid modification of Grocott stains to peripheral blood smears in a hematological study.

The combination of both stains was applied consecutively (first Grocott and then Giemsa) to previously fixed peripheral blood smears. Microscopy was performed with 400× and 1 000×, the latter using immersion oil.

The yeasts of Histoplasma capsulatum were observed into the cytoplasm of leukocytes as brownish oval elements, with 3-4 µm in diameter.

The combination of both techniques is a simple and fast method to facilitate recognition of intracellular yeasts and it is different from intracellular parasitic elements. Moreover, it allows distinguishing the cell elements that are in the microscopic preparations. It may be very helpful in those cases in which the presumptive diagnosis of histoplasmosis has not been established yet and where other more sophisticated methods are not available.