ABSTRACT
Background: Histoplasmosis is a rare cause of infective endocarditis. Here we describe a case of disseminated histoplasmosis involving a prosthetic aortic valve (AV). Case: A 50-year-old male from Ohio, with history notable for congenital aortic valve disease status post bioprosthetic AV replacement (AVR) in 2014, presented with 6 months of flu-like illness, pancytopenia, and suspected transient ischemic attack after receiving the COVID-19 Johnson & Johnson vaccine, posing concern for post-vaccination reaction. However, COVID-19 polymerase chain reaction testing was negative. Detailed workup revealed myelodysplastic syndrome and positive urine histoplasmosis antigen. Chest computed tomographic angiography (CTA) demonstrated a 16x16 mm left lower lobe pulmonary nodule with central cavitation suspicious for pulmonary histoplasmosis. Transesophageal echocardiography (TEE) showed bulky thickening of the prosthetic leaflets with suspected vegetation causing severe prosthetic aortic stenosis. Head and neck CTA showed no mycotic aneurysms. Decision-making: He was treated with Amphotericin B and underwent redo AVR. Intraoperative findings included a very large vegetation with near-total obstruction of the aortic valve and circumferential necrotic tissue of the aortic root (Figure 1). Conclusion: Despite its rare incidence, histoplasmosis should remain on the differential for infective endocarditis in patients presenting with systemic illness and prosthetic valves. [Formula presented]