BCGitis after Bacille Calmette-Guerin intravesical administration from two referral centers: clinical characteristics and risk factors.

Bacillus Calmette-Guerin (BCG) is commonly and safely used as intravesical instillation to treat bladder cancer. Adverse effects are widely described in case report and series with a broad range of clinical presentations known as "BCGitis". Moreover, microbiological identification is often inconclusive leading to diagnostic uncertainty and no standardisation of definitions is available. We retrospectively collected all cases of BCGitis (n=19) after BCG intravesical administration occurred in 2 major Italian hospitals in the last 10 years. Median age was 71.8 years and among comorbidities hypertension affected 60% of patients. The delay in the onset of symptoms was < one week and an inverse correlation was observed between the number of instillations and the time to the onset of symptoms. Moreover, a febrile presentation was the commonest clinical symptom (85%) and an interstitial or micronodular pattern at chest X-ray or CT scan was found positive in about 70% and 90% of cases, respectively. Larger cohorts are needed in order to inform clinically relevant algorythms for this uncommon disease.