Escaped surveillance: tuberculosis masked by severe hyponatremia in an immunocompromised patient: a case report

Tuberculosis in immunosuppressed individuals frequently presents atypically and may produce false-negative screening results, delaying diagnosis. Hyponatremia and features of inappropriate antidiuretic hormone secretion can mimic paraneoplastic processes, further complicating the clinical picture. This case describes the challenges of diagnosing tuberculosis in a patient receiving prolonged corticosteroid therapy. A 74-year-old East Asian woman with long-standing myasthenia gravis treated with prednisone presented with 1 month of progressive weakness, weight loss, gastrointestinal symptoms, cough, shortness of breath, and persistent hyponatremia. Coronavirus disease screening and tuberculin skin testing were negative. Chest imaging revealed a right upper-lobe mass and diffuse pulmonary nodules concerning malignancy. Lung biopsy demonstrated necrotizing granulomatous inflammation, and acid-fast staining of sputum, stool, and ileal tissue confirmed tuberculosis with extrapulmonary ileal involvement. Shortly after initiation of first-line antituberculosis therapy, she developed significant liver injury requiring modification of the regimen. Although she initially improved, she returned 20 days after discharge with abdominal distension and pain due to tuberculosis-associated peritonitis and small-bowel obstruction, necessitating surgical resection. Negative screening results cannot reliably exclude tuberculosis in immunosuppressed patients. The combination of hyponatremia, nonspecific constitutional symptoms, and atypical pulmonary imaging should prompt early microbiologic evaluation to prevent delay, dissemination, and severe complications.