An immunocompetent 82-year-old female was admitted to our hospital due to fever without clear origin and hyponatremia. In the following days, an acute and bilateral pulmonary infiltrate appeared with a progressive worsening in respiratory function. Chest x-ray and CT (Computed tomography) showed bilateral reticulonodular infiltrates. Bronchoscopic aspiration and bronchoalveolar lavage (BAL), and transbronchial lung biopsy (TBBX) studies did not reveal microbiological and histopathological diagnosis. Broad-spectrum antibiotics were non-effective, and the patient died due to respiratory failure. Necropsy study revealed a miliary tuberculosis affecting lungs, liver, bone marrow, spleen, kidney, arteries, pancreas, and adrenal glands. Some weeks after the patient´s death, mycobacterial cultures from sputum, BAL and TBBX samples were positive for Mycobacterium tuberculosis.