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.