ACUTE PULMONARY HISTOPLASMOSIS: A DIAGNOSTIC DILEMMA DURING COVID-19 PANDEMIC

Abstract

TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: Acute histoplasmosis is usually a concern in immunocompromised individuals. In immunocompetent patients, histoplasmosis is generally mild or asymptomatic unless there is inhalation of a large inoculum. Below, we present a case of severe acute pulmonary histoplasmosis in an otherwise healthy, immunocompetent person and discuss the diagnostic challenges it presented during the COVID-19 pandemic. CASE PRESENTATION: A 30-year-old non-smoking Caucasian man with hypertension presented to our hospital with 1 week duration of headache, dyspnea, productive cough and high fever. He was admitted with a provisional diagnosis of COVID-19 pneumonia and started on dexamethasone and empiric antibiotics. He had elevated inflammatory markers. Chest x-ray showed diffuse bilateral interstitial and alveolar opacities. CT chest demonstrated numerous clustered ground glass nodular opacities bilaterally with mediastinal and hilar adenopathy. Subsequently, RT-PCR for SARS-CoV2 returned negative. The patient continued to deteriorate clinically over the next few days. Repeat imaging showed diffuse micronodules with mediastinal adenopathy. Upon further questioning, the patient recalled demolishing a chimney at his parents' house in Michigan 2 weeks prior to admission. The differential diagnosis was broadened to include acute hypersensitivity pneumonitis and fungal infection. BAL, transbronchial biopsies and EBUS-TBNA was performed while escalating steroids. The lung biopsy confirmed Histoplasma. Urine Histoplasma antigen returned positive. The patient was treated with itraconazole with an overlap of steroids for 2 weeks upon discharge. He was readmitted within a week with worsening hypoxia and worsening infiltrates on lung imaging. He was then treated with liposomal amphotericin with gradual clinical improvement. Follow-up 1 month post discharge revealed complete clinical and radiologic resolution. DISCUSSION: Viral pneumonia and acute pulmonary histoplasmosis have overlapping clinical and radiologic features which can make diagnosis challenging. COVID-19 pneumonia typically presents with peripheral ground glass opacities with or without superimposed consolidations. Invasive fungal pneumonia can have a similar appearance on CT usually with additional findings of hilar and mediastinal adenopathy. CONCLUSIONS: This case highlights the challenges involved in diagnosing acute pulmonary histoplasmosis in an immunocompetent individual in the midst of the pandemic. Clinicians should always maintain a wide differential diagnosis to avoid diagnostic delay. REFERENCE #1: Staffolani, S., Buonfrate, D., Angheben, A., Gobbi, F., Giorli, G., Guerriero, M., Barchiesi, F. (2018). Acute histoplasmosis in immunocompetent travelers: A systematic review of literature. BMC Infectious Diseases, 18(1). doi:10.1186/s12879-018-3476-z REFERENCE #2: Duzgun, S. A., Durhan, G., Demirkazik, F. B., Akpinar, M. G., & Ariyurek, O. M. (2020). COVID-19 pneumonia: the great radiological mimicker. Insights into imaging, 11(1), 118. https://doi.org/10.1186/s13244-020-00933-z REFERENCE #3: Klein, M., Khan, M., Salinas, J. L., & Sanchez, R. (2019). Disseminated pulmonary histoplasmosis in immunocompetent patients: A common epidemiological exposure. BMJ Case Reports, 12(3). doi:10.1136/bcr-2018-227994 DISCLOSURES: No relevant relationships by Joseph Arguinchona, source=Web Response No relevant relationships by Michael Kaster, source=Web Response No relevant relationships by Muazzam Mirza, source=Web Response No relevant relationships by Anusha Pinjala, source=Web Response no disclosure on file for Venketraman Sahasranaman;