Endobronchial tuberculosis with atypical radiological images and features in association with long-term use of inhaled corticosteroid for bronchial asthma: lessons from the case and literature review.

A 57-year-old man presented with endobronchial tuberculosis (EBTB). He had a history of using inhaled corticosteroids (ICS) for years since asthma was diagnosed during childhood. The present case was remarkable in that ICS alone may have affected the onset and progression of the EBTB. In addition, diagnosing the patient's condition apparently was challenging because he had atypical epidemiology, diagnostic imaging findings, and sites of occurrence for tuberculosis. The CT images revealed no cavitation, which is reported to be relatively specific and typical for tuberculosis. And then, it demonstrated mixed shadows indicating consolidation in the lower lobe and tree-in-bud, which are not specific. And the patient had no other risk factors of tuberculosis but prolonged ICS use. Tuberculosis was also cited as the differential diagnosis based on the chronic clinical course, bronchial wall calcification, and the tree-in-bud sign on imaging, not being highly suspected overall. To understand the clinical condition, we performed bronchoscopy. As a result, EBTB and pulmonary tuberculosis were diagnosed. Even when findings are largely atypical for tuberculosis, it should be strongly considered in the differential diagnosis when any typical elements, which are sometimes not specific, are encountered. It is also because EBTB is reported to be extremely transmissible owing to its high rate of bacterial shedding. Moreover, the recognition of the risk of reactivation especially in patients with asthma using ICS will also be important in the future although the possibility that ICS can affect it has been discussed for a long time.