Malakoplakia is a treatable inflammatory reaction to bacteria, mycobacteria, or fungi that may occur in immunocompromised patients. Usually occurring in the urinary tract, it has also been reported in the lungs. The inflammation is characterized by enlarged, granular macrophages, scattered PMNs, and characteristic concentrically lamellated, calcified structures called Michaelis-Gutman bodies. Recently, a number of cases caused by Rhodococcus equi have been reported in AIDS patients. Malakoplakia usually occurs in the lung parenchyma rather than in the bronchi [1].

Low Power


Find a region with inflammatory cells and cell debris.

Malakoplakia--High Power


Also characteristic of lesions of malakoplakia are rounded intra- or extracellular inclusions representing giant lysosomes. They contain organisms and often calcify. These inclusions are known as Michaelis-Gutman bodies.

Find 2 cells containing Michaelis-Gutman bodies.

The presence of inflammation and Michaelis-Gutman bodies help to distinguish this lesion from giant cell tumor, which the patient in the unknown case presentation had.


1. Shin M, Cooper J, Ho K. Pulmonary malacoplakia associated with Rhodococcus equi infection in a patient with AIDS. Chest 1999; 115:889-892. abstract

Return to histologic differential diagnosis.

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Inflammation with cell debris




























Cell with Michaelis-Gutman body at lower pole