Beyond the usual suspects: Adrenal histoplasmosis masquerading as fever of unknown origin

Histoplasmosis, a mycotic infection caused by Histoplasma capsulatum , is endemic in certain regions, including parts of India. Disseminated histoplasmosis (DH) predominantly affects immunocompromised individuals but can occasionally involve immunocompetent patients, presenting diagnostic challenges. Adrenal involvement in DH is rare, with primary adrenal insufficiency occurring in a minority of cases. This case report describes a 59-year-old immunocompetent farmer from rural Rajasthan, India, who presented with progressive fatigue, weight loss, and intermittent fever. Clinical findings included hyperpigmentation, postural dizziness, and hepatosplenomegaly, with imaging revealing bilateral adrenal masses. Laboratory tests confirmed primary adrenal insufficiency, and a computed tomography-guided biopsy of the adrenal mass revealed H. capsulatum organisms. The patient was treated with intravenous liposomal amphotericin B followed by oral itraconazole, along with glucocorticoid and mineralocorticoid replacement. The patient’s condition improved significantly, with resolution of symptoms and adrenal function normalization. This case underscores the importance of considering fungal infections like histoplasmosis in the differential diagnosis of adrenal insufficiency in endemic regions.