Pulmonary Histoplasmosis Presenting in a Man With AIDS

Abstract

INTRODUCTION: In patients with AIDS, pulmonary histoplasmosis can have a similar clinical presentation to Pneumocystis jiroveci Pneumonia (PJP) and distinguishing between the two can be difficult. We present such a case in a gentleman returning from Trinidad. CASE PRESENTATION: A 43 year old man with HIV, not taking antiretrovirals, presented with two months of fatigue and 25lbs weight loss. He immigrated from Trinidad in 2007 and last visited five months prior to admission. Exam was notable for low grade temperature, normal oxygen saturation, cachexia, temporal wasting, and clear lungs. Room air blood gas was 7.49/30/73/23. Labs were notable only for LDH 3470U/L and CD4 1cell/mm3. Blood cultures were negative. A chest CT (figure1) was performed. Empiric treatment for (PJP) with oral trimethoprim-sulfamethoxazole was started. Three sputums samples were AFB smear negative. Bronchoscopy with BAL and TBBX was performed (figure2). DISCUSSION: Histoplasmosis Capsulatum is the dimorphic fungal agent responsible for pulmonary histoplasmosis. H. capsulatum mycelia are dropped in soil by bird or bat guano, and can be found in high concentrations in chicken coops, decayed trees, and caves. Distinguishing this infection from PJP can be difficult as the clinical manifestations of both infections are non-specific, resulting in dyspnea, fevers, cough, and weight loss. LDH can be elevated in both PJP and histoplasmosis, and at levels greater than 1000U/L, LDH may be more specific for histoplasmosis infection(1). Chest x-ray can show reticular opacities in patients infected with PJP or histoplasmosis,(2). Chest CT may differentiate the two, demonstrating ground glass opacities in PJP and micronodules in histoplasmosis. Even with tissue sections, the two can be confused as both can appear as small yeasts on histologic analysis(3). CONCLUSIONS: It is important to consider all the clinical, radiologic, and pathologic clues available when distinguishing histoplasmosis from other pulmonary infections, while taking into account that patients with AIDS may have multiple infections simultaneously. In our patient, a diagnosis of disseminated histoplasmosis and PJP co-infection was made and liposomal amphotericin was added to his regimen of oral trimethoprim/sulfamethoxazole.