Diagnostically Challenging Disseminated Bacillus Calmette-Guerin Infection With Lung and Liver Involvement: A Case Report.

Intravesical Bacillus Calmette-Guerin (BCG) therapy is the standard treatment for non-muscle-invasive bladder cancer. While it is effective, it sometimes causes a disseminated BCG infection, which is often difficult to diagnose microbiologically. We report herein a 73-year-old, male patient in whom a persistent fever, dyspnoea, and jaundice developed after he received his tenth round of intravesical BCG therapy. Chest computed tomography revealed diffuse micronodules, and lung and liver biopsies demonstrated multiple, well-formed, non-caseating granulomas. Despite negative microbiological test results, a disseminated BCG infection was suspected. Antimycobacterial therapy was started but discontinued after 2 weeks due to a drug-induced eruption. The clinical and radiological findings continued to improve without further treatment. The present case highlights the importance of a detailed assessment of radiological and histopathological findings for the diagnosis and management of diffuse lung diseases, including complications related to intravesical BCG therapy.