Pulmonary Infections in AIDS

Basics

• Patients with CD4 counts < 500 cells/mm³ are at increased risk for: bacterial pneumonia and pulmonary tuberculosis.
• Patients with CD4 counts < 200 cells/mm³ are also at increased risk for Pneumocystis jiroveci pneumonia and disseminated tuberculosis.
• Patients with CD4 counts < 100 cells/mm³ are also at increased risk for fungal and Cytomegalovirus pneumonia.

Bacterial Pneumonia

Findings are similar to those seen in immunocompetent patients: single or multifocal areas of consolidation.

Tuberculosis

In patients with CD4 counts > 200 cells/mm³, findings are similar to those seen in reactivation tuberculosis in immunocompetent patients: Single 1- to 3-cm nodules, consolidation, cavitation (mainly the upper lobes), and tree-in-bud opacities.

In patients with CD4 counts > 100 cells/mm³, findings are similar to those of primary tuberculosis: areas of consolidation, miliary disease, pleural effusion, and enlarged lymph nodes (with necrotizing granulomas).

Pneumocystis jiroveci pneumonia

The most common HRCT finding is confluent, symmetric, bilateral ground-glass opacities, but patients may also present with consolidation, interlobular septal thickening, cystic lesions (~20% of cases, mainly upper lobes), nodules, and crazy paving.

Fungi

Histoplasmosis and coccidioidomycosis: The most common finding is a miliary pattern, but diffuse air-space consolidation can also be seen. Cyst formation can be seen in coccidioidomycosis.

Invasive pulmonary aspergillosis: The most common findings are thick-walled cavitary lesions (pulmonary infarction and abscess formation). Less common findings include single or multiple nodules (with or without ground-glass halos), patchy areas of consolidation, and pleural effusions.

Cryptococcosis: Findings include bilateral nodular or reticular opacities, bilateral consolidation, or miliary nodules. Extensive tissue infiltration with cavitation may be seen in patients with severe immunocompromise.

Cytomegalovirus Pneumonia

Findings are variable and include: bilateral ground-glass opacities, patchy bilateral consolidation, and multiple nodules or mass-like areas of consolidation.

References

Marchiori E, Müller NL, Soares Souza A Jr, Escuissato DL, Gasparetto EL, Franquet T. Pulmonary disease in patients with AIDS: high-resolution CT and pathologic findings. AJR Am J Roentgenol. 2005 Mar;184(3):757-64.