Disseminated Bacillus Calmette-Guerin infection: role of imaging in the evaluation of complications

Background: The Bacillus Calmette-Guerin (BCG) vaccine is generally used to prevent tuberculosis, particularly meningeal and miliary types, in childhood. This vaccine can rarely cause complications of varying severity, ranging from localized disease to a severe diffuse type known as disseminated BCG infection. Imaging modalities play an important role in the evaluation of different complications of disseminated BCG infection. This study aimed to assess and describe the imaging findings of disseminated BCG infection in order to help clinicians diagnose this life-threatening infection more accurately. Methods: This retrospective study was performed on 44 hospitalized children diagnosed with disseminated BCG infection. The results of radiographs, sonography, computerized tomography (CT) scan and magnetic resonance imaging were compiled in a checklist and were then assessed by a radiology resident and a board-certificated radiologist. The radiological findings from various imaging modalities were presented descriptively and the frequency of different parameters was reported. Results: Axillary lymphadenopathy at the vaccinated side was frequent and was often associated with abscesses. However, abscesses in other body regions were uncommon. The most common abdominal imaging findings were enlarged liver and spleen accompanied by multiple hypoechoic and hypodense nodules on ultrasound and CT scans, respectively. Furthermore, diffuse or multifocal pulmonary opacities were the most frequent findings on chest X-rays and CT scans. Conclusion: Characteristic imaging findings of disseminated BCG infection play a vital role in the early diagnosis of this infection. The study findings demonstrated the importance of radiological imaging in the diagnosis and evaluation of the complications of disseminated BCG infection.