Pulmonary malacoplakia associated with Rhodococcus equi infection in a patient with AIDS

We describe a 35-year-old man infected with the human immunodeficiency virus, who on initial examination was found to have cavitary tumoral lung lesion in right lower lobe. Histologic examination revealed sheets of foamy intraalveolar macrophages with the typical histologic features of Michaelis-Gutmann bodies that contained coccobacillary organisms and some "targetlike" cytoplasmic inclusions, so pulmonary malacoplakia probably associated to Rhodococcus equi was diagnosed. Cultures of blood yielded growth of Gram-positive coccobacilli subsequently identified as Rhodococcus equi. Rhodococcus equi is a pathogen for some animal species, an Gram-positive coccobacillus that cause pulmonary infections in immunocompromised people. Pulmonary malacoplakia associated with this opportunistic coccobacillus is unusual, and pseudotumoral lesions are exceptional, and the recognition of this unique entity is important because of its responsiveness to therapy.