Introduction: Histoplasmosis is a rare opportunistic, inhalation-acquired systemic mycosis caused by Histoplasma capsulatum, endemic to Southeast Asia, including Malaysia. Although classically seen in immunocompromised hosts, it is increasingly reported in immunocompetent individuals. Infection is associated with environmental exposures such as bat or bird droppings and soil disruption. Histoplasmosis is a progressive granulomatous disease that can closely mimic tuberculosis and malignancy, making diagnosis challenging. Case: An 87-year-old Malay male with a history of treated pulmonary tuberculosis presented with a 6-month history of intermittent fever, anorexia, weight loss, and hypotension. Initial computed tomography imaging demonstrated bilateral heterogeneous adrenal masses (right: 2.2 × 3.7 × 5.0 cm; left: 2.0 × 3.7 × 5.2 cm) with indeterminate washout characteristics. Biochemical adrenal evaluation, including a short Synacthen test, confirmed primary adrenal insufficiency. Extensive microbiological and malignancy workup, including bronchoscopy, cultures, and tumor markers, was non-diagnostic. In view of clinical deterioration and epidemiological risk, empirical antituberculous therapy was initiated; however, no clinical improvement was observed after 2 months. PET-FDG revealed intensely hypermetabolic bilateral adrenal masses (SUVmax right 16.7, left 13.2) with no other abnormal foci. Non-invasive fungal investigations were negative. Definitive diagnosis was established via computed tomography-guided adrenal biopsy, which demonstrated necrotizing granulomatous inflammation with intracellular yeasts, subsequently identified as H. capsulatum. The patient was treated with oral itraconazole and corticosteroid replacement, resulting in significant clinical improvement and planned interval radiological reassessment. Conclusion Disseminated histoplasmosis is a diagnostic challenge, particularly in frail elderly patients, where invasive procedures may be delayed. It can mimic tuberculosis and malignancy and may lack an identifiable exposure history. Non-invasive tests may be inconclusive, making tissue biopsy essential. Adrenal involvement may result in primary adrenal insufficiency, further complicating the clinical picture. Early consideration and timely confirmation are crucial for appropriate management.
Adrenal incidentaloma ; Lung Neoplasms