Discussion:
Dysphagia is the most common presenting symptom of esophageal TB; however, this is a common presenting symptom of a rare disease.5-7 Other symptoms of esophageal TB include chest pain, fever, odynophagia, and weight loss.
Endoscopic findings of esophageal TB can vary, but typically present as either ulcerated, bulging mucosal or submucosal mass and rarely as a stricture or fistula.5,8-10 Given its appearance, upper gastrointestinal TB is often mistaken for malignancy in reported cases, as it was in our case.11,12
Adding to the diagnostic dilemma was the fact that our patient was both previously vaccinated with BCG and had a prior negative TST five months before presentation. BCG has an effectiveness of 46-50% regardless of the time of vaccination.13,14 TST has a sensitivity of 60-98% but is prone to false-negative results from technical errors or decreased skin reactivity.15 Acid-fast bacilli staining on biopsied tissue has high specificity but low sensitivity for TB.16 Instead, tissue PCR should be used, given the higher sensitivity estimated to be between 74% to 100% with most false-negatives as a result of insufficient tissue sampling.16-18
The most common etiology of esophageal TB is local spread from adjacent respiratory tract or mediastinal lymph nodes.5,19While our patient had no respiratory symptoms, normal chest x-ray, and negative TST, lung scarring seen on her CT chest may indicate latent pulmonary TB. Lymphadenopathy was absent on both EUS and cross-sectional imaging, making spread from lymph nodes less likely.
Other than enlarged lymph nodes, other EUS features of esophageal TB include thickened esophageal wall and hypoechoic lesions that may contain hyperechoic calcifications, which we did not see in our patient.19 However, none of these features is sensitive nor specific to esophageal TB.
Primary esophageal TB is also unlikely as it is rare and occurs when mycobacterium tuberculosis adheres to the esophageal wall after direct ingestion and needs to bypass protective mechanisms such as the mucus barrier and stratified squamous epithelium of the esophagus.9,19
Despite previous vaccination, a negative skin test, and the absence of other features of TB other than generalized weight loss, our patient was found to have esophageal and duodenal TB. Although rare in a Western setting, an index of suspicion is needed to keep gastrointestinal TB as part of the differential for workup of dysphagia for patients from endemic areas, even with prior BCG vaccination and negative screening TST.