Extrapulmonary Pneumocystis Disease

Pneumocystis can spread to extrapulmonary sites. Although such spread is very rare in non-AIDS patients, it has been reported to occur in up to 13% of autopsied AIDS patients [1]. However, it is recognized less frequently in clinical series of AIDS patients (0.5%) [2]. Further, concurrent or prior pneumocystis pneumonia need not be present. Dissemination may occur via blood vessels or lymphatics. In general, diagnosis is made by thinking about it and obtaining tissue. In some cases, CT scans show focal calcifications that suggest the diagnosis [3].


Figure 1. Hematogenous Dissemination

Here, a clump of foamy exudate is present in a pleural blood vessel.

Find the foamy intravascular exudate.

Figure 2. Pneumocystis in the Liver

Here, liver cells are replaced by foamy exudate. A few scattered macrophages are present in the exudate at the upper right. Otherwise, inflammatory cells are sparse. Lesions may develop punctate or rimlike calcifications. Note the punctate calcifications at the arrow.

On CT, extrapulmonary lesions appear as foci of low-attenuation ± calcification [3].

References: To return to reference section after viewing abstract, click here before clicking on "abstract".

1. Afessa B, Green W, Chiao J, Frederick W. Pulmonary complications of HIV infection: autopsy findings. Chest 1998; 113:1225-1229. Abstract

2. Ng V, Yajko D, Hadley W. Extrapulmonary pneumocystosis. Clin Microbiol Rev 1997; 10:401-418. Abstract

3. Lubat E, Megibow A, Balthazar E, Goldenberg A, Birnbaum B, Bosniak M. Extrapulmonary Pneumocystis carinii infection in AIDS: CT findings. Radiology 1990; 174:157-160. Abstract

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Foamy intravascular exudate