A RARE CASE OF HISTOPLASMOSIS PRESENTING WITH PLEURAL EFFUSION IN A NORMAL HOST

Abstract

SESSION TITLE: Monday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: Histoplasmosis is an endemic mycosis that is usually asymptomatic in healthy hosts. We present a rare case of pulmonary histoplasmosis presenting with pleural effusion in an immunocompetent patient. CASE PRESENTATION: A 44 year old male smoker presented to the emergency department with progressive left-sided pleuritic pain, cough, night sweats, and weight loss. Chest x-ray was unremarkable and he was released to follow-up with primary care. His symptoms persisted and chest CT obtained three weeks later revealed a 2.5 cm left lower lobe pleural-based nodule, left hilar lymphadenopathy, and a small left-sided pleural effusion. Thoracentesis yielded 520 ml of exudative pleural fluid with 43% lymphocytes and 16% eosinophils. Testing for histoplasmosis including urine and serum antigens as well as serology were negative. However, pleural fungal culture grew Histoplasma capsulatum. Fluid reaccumulated within a week and repeat thoracentesis again grew H. capsulatum. In the interim, the patient was initiated on itraconazole and pleural effusion resolved. DISCUSSION: Histoplasmosis is a mycosis caused by H. capsulatum which is transmitted via inhalation of microconidia and associated with environments containing bird or bat guano. Infection is generally asymptomatic in healthy hosts and resolves through cell-mediated immunity. However, with large inoculum pulmonary histoplasmosis can manifest in an acute, subacute, or chronic illness. Acute pulmonary histoplasmosis is characterized by fever, dyspnea, and cough with chest imaging showing bilateral patchy opacities, nodules, and lymphadenopathy. In contrast, subacute pulmonary histoplasmosis progresses over several months and imaging reveals more focal opacities. Chronic histoplasmosis is characterized by exacerbations of cough, dyspnea, fever, chest pain, night sweats, and weight loss with radiographic features of cavitation, fibrosis, pleural thickening, and calcified lymph nodes. Pleural effusion secondary to any form of histoplasmosis is exceedingly rare. Diagnosis of histoplasmosis is made via identification of ovoid yeast cells in tissue or body fluid, cultures of blood, sputum, or bronchoscopy specimens, serum and urine antigen, or antibody testing. Antigen testing provides highest yield in acute pulmonary and disseminated histoplasmosis. Combined serum and urine antigen is reportedly 81% sensitive and 99% specific, and therefore negative antigen does not rule out infection as was the case with our patient who had positive pleural culture despite negative antigen testing. CONCLUSIONS: Pulmonary histoplasmosis can present with a variety of clinical and radiographic findings depending upon size of inoculum and immune status of the host. Diagnosis can be challenging and relies on a combination of culture, pathology, antigen, and serologic testing. Our patient is a very rare case of histoplasmosis presenting with culture positive pleural effusion. Reference #1: Wheat, L.J.; Azar, M.M.; Bahr, N.C.; Spec, A.; Relich, R.F.; Hage, C. Histoplasmosis. Infect Dis Clin N Am 30. 2016; 207-227. https://doi.org/10.1016/j..idc.2015.10.009. Reference #2: Di Mango, A.L.; Zanetti, G.; Penha, D.; Mebba Barreto, M.; Marchiori, E. Endemic pulmonary fungal diseases in immunocompetent patients: an emphasis on thoracic imaging. Exper Rev Respir Med. 2019; 13(3): 263-277. https://doi.org/10.1080/17476348.2019.1571914. Reference #3: Patterson, J.; Graham, D.; George, A.; Will, M.; Sutter, D. Right Middle Lobe Collapse and Pleural Effusion in an 18-Year-Old-Man. Chest. 2017; 152(2):e33-e38. DISCLOSURES: No relevant relationships by Brian Boer, source=Web Response No relevant relationships by Amber Johnson, source=Web Response