Disseminated Bacillus Calmette–Guérin (BCG) infection and acute exacerbation of interstitial pneumonitis: an autopsy case report and literature review

BACKGROUND: Intravesical administration of Bacillus Calmette–Guérin (BCG) has proven useful for treatment and prevention of recurrence of superficial bladder cancer and in situ carcinoma. However, fatal side effects such as disseminated infections may occur. Early diagnosis and accurate therapy for interstitial pneumonitis (IP) are important because exacerbation of IP triggered by infections is the major cause of death. Although some fatality reports have suggested newly appeared IP after intravesical BCG treatment, to our knowledge, there are no reports which have demonstrated acute exacerbation of existing IP. Moreover, autopsy is lacking in previous reports. We report the case of a patient with fatal IP exacerbation after BCG instillation and the pathological findings of the autopsy. CASE PRESENTATION: A 77-year-old man with a medical history of IP was referred to our hospital because of fever and malaise. He had received an intravesical injection of BCG 1 day before the admission. His fever reduced after the use of antituberculosis drugs, so he was discharged home. He was referred to our hospital again because of a high fever 7 days after discharge. On hospitalisation, he showed high fever and systemic exanthema. Hepatosplenomegaly and myelosuppression were also observed. Biopsies revealed multiple epithelioid cell granulomas with Langhans giant cells of the liver and bone marrow. Biopsy DNA analyses of Mycobacterium bovis in the bone marrow, sputum, and blood were negative. His oxygen demand worsened drastically, and the ground-glass shadow expanded on the computed tomography scan. He was diagnosed with acute exacerbation of existing IP. We recommenced the antituberculosis drugs with steroid pulse therapy, but he died on day 35 because of respiratory failure. The autopsy revealed a diffuse appearance of multiple epithelioid cell granulomas with Langhans giant cells in multiple organs, although BCG was not evident. CONCLUSIONS: We report the first case of acute exacerbation of chronic IP by BCG infection. This is also the first case of autopsy of a patient with acute exacerbation of existing IP induced by intravesical BCG treatment. Whether the trigger of acute IP exacerbation is infection or hypersensitivity to BCG is still controversial, because pathological evidence confirming BCG infection is lacking. Physicians who administer BCG against bladder cancer should be vigilant for acute exacerbation of IP.