An 81-year-old man with idiopathic pulmonary fibrosis (IPF) came to our hospital with symptoms of fever and worsening dyspnea. We diagnosed an acute exacerbation of IPF (AE-IPF) on the basis of the findings of high-resolution computed tomography of the chest and thus started steroid therapy. However, we detected Mycobacterium tuberculosis in the sputum and concluded that pulmonary tuberculosis coexisted with AE-IPF. Because high-resolution computed tomography showed circumscribed consolidation in S10 of the left lung, we suspected that the consolidation was the focus of the tuberculosis. We started treatment of the pulmonary tuberculosis with antituberculous drugs; however, we were unable to control the AE-IPF, and the patient died. Interpreting the imaging findings of infection is difficult, particularly in cases of AE-IPF, which is associated with consolidation and may coexist with infection. The frequency of tuberculosis was higher in patients with IPF than in the general population. In cases of AE-IPF caused by infection, screening sputum tests, including those for acid-fast bacteria, are useful.
