Acute microbiologically negative hypoxic interstitial pneumonia on HAART: Immune Reconstitution Inflammatory Syndrome unmasking Pneumocystis Jiroveci infection with an atypical presentation
Immune restoration syndromes (IRS) in AIDS constitute a group of illness characterized by a pathologic inflammatory response in patients with late-stage AIDS who start highly active antiretroviral therapy. Although there is no standardized definition or therapy, IRS have partial immune restoration associated with an increase in their CD-4 cell count and a decrease in their viral load. Patients with IRS show a paradoxical reaction that is, clinical worsening rather than improvement on therapy, associated with a recognized or occult infection. Symptoms include new or worsening fever, lymphadenopathy, pulmonary, visceral, central nervous system, or cutaneous disease which may be severe and occasionally life threatening and must be differentiated from disease progression. In this paper, we review the clinical and associated thoracic imaging findings of IRS associated with specific infections including mycobacterial and fungal infections, cytomegalovirus, Pneumocystis jiroveci pneumonia and also Kaposi sarcoma and sarcoidosis. Recognition of the imaging findings in the appropriate clinical setting presents an opportunity to make a timely diagnosis. With appropriate management, IRS usually does not alter long-term prognosis.