Unilateral Pneumocystis-associated immune reconstitution inflammatory syndrome: A case illustrated.

A man in his 50 s presented with severe Pneumocystis jirovecii pneumonia (PCP) with newly diagnosed advanced HIV infection. Initial chest computed tomography (CT) revealed diffuse bilateral ground-glass opacities that improved after standard therapy. Seven days after antiretroviral therapy initiation, fever, dyspnea, and hypoxemia recurred, and repeat CT revealed new predominantly left-sided reticular and fibrosis-like opacities. Paradoxical PCP-associated immune reconstitution inflammatory syndrome (IRIS) was diagnosed based on the clinical course and lack of a more likely alternative diagnosis. This case expands the radiologic spectrum of PCP-associated IRIS by demonstrating a markedly asymmetric, fibrosis-like presentation following the apparent resolution of bilateral PCP.