An AIDS patient with a cavitary lung lesion was found to have pulmonary malacoplakia associated with Rhodococcus equi infection. The diagnosis was based on the typical histologic features of transbronchial biopsy and a positive bacterial culture. All 13 reported eases of AIDS patients with pulmonary malacoplakia were associated with R equi. The recognition of this unique entity is important because of its responsiveness to therapy.
