Immunocompromised patients ave at risk of developing infections caused
by Rhodococcus equi, a grampositive bacillus that can cause pneumonia
in patients with acquired immunodeficiency syndrome. To the author's
knowledge this is the first report describing the cytologic features o
f the infection in a patient who had a confirmatory tissue biopsy and
positive culture. Infection with R equi may go unrecognized by patholo
gists unaware of its presentation and appearance in cytologic material
.