Disseminated Bacillus Calmette-Guérin (BCG) Infection Presenting With a Miliary Pulmonary Pattern Following Intravesical Therapy.

Intravesical administration of Bacillus Calmette-Guérin (BCG) is a commonly employed therapeutic approach in clinical practice for the treatment of bladder neoplasms. Although it is generally safe, severe systemic complications may rarely arise. This report describes a patient with non-invasive papillary urothelial carcinoma treated with intravesical BCG therapy who developed disseminated infection with a miliary pattern. Although multiple attempts were made to isolate Mycobacterium bovis from blood, urine, and sputum samples, microbiological confirmation was never obtained. The diagnosis was therefore established presumptively based on the clinical presentation and epidemiological context, and anti-mycobacterial therapy was initiated accordingly. The patient's favorable clinical response to treatment further supported the diagnosis. This report describes a rare complication and a challenging diagnosis that should be considered in patients undergoing this form of treatment.