Haemolytic anaemia due to severe melody pulmonary valve stenosis caused by Histoplasma capsulatum infective endocarditis: a case report

Isolated pulmonary valve infective endocarditis (IE) is exceedingly rare, accounting for <2% of IE cases. Haemolysis due to right-sided prosthetic valve dysfunction is also poorly described.

We present a patient with tetralogy of Fallot and a Melody pulmonary valve replacement who presented with dyspnoea on exertion and scleral icterus found to have isolated pulmonary valve IE caused by Histoplasma capsulatum, resulting in severe valve stenosis and intravascular hemolysis. Diagnosis was established through exclusion of other causes of hemolysis, transthoracic echocardiography showing severe prosthetic stenosis, and infectious evaluation identifying H. capsulatum, confirmed by histopathology of the explanted valve. The patient was treated with antifungal therapy followed by surgical pulmonary valve replacement, leading to clinical improvement.

Fungal endocarditis due to Histoplasma is rare, particularly involving the pulmonary valve. Haemolysis from right-sided valve dysfunction is an extraordinarily rare clinical presentation. This case highlights the importance of considering prosthetic valve IE in unexplained haemolysis and using multimodal diagnostic strategies.