Acute microbiologically negative hypoxic interstitial pneumonia on HAART: Immune Reconstitution Inflammatory Syndrome unmasking Pneumocystis jiroveci infection with an atypical presentation.

Highly active antiretroviral therapy for AIDS sometimes engenders inflammatory manifestations resulting from an inappropriate and unbalanced immune-system restoration, called Immune Reconstitution inflammatory Syndrome, which, in turn, can unmask a subclinical infection/pathology. Despite our patient's evident syndrome, the atypical clinical, microbiologic and radiologic feature of Pneumocystis pneumonia made its diagnosis difficult.