S2195 A Masquerade Ball at the Descending Colon

Abstract

Introduction: Abdominal tuberculosis (TB) accounts for up to 5% of TB cases worldwide and the proximal colon is the most affected site. It can involve any part of the GI tract, however, TB in the descending colon is rarely reported. Most cases present with non-specific symptoms and without concomitant pulmonary TB making the diagnosis challenging and delayed. Case Description/Methods: An 80-year-old man was found with new-onset microcytic anemia on routine labs. His PCP ordered a FIT test which came back positive. He reported being asymptomatic and denied GI bleeding. Diagnostic colonoscopy was performed which revealed a tumorous lesion in the descending colon occupying over 50% of the lumen. Preliminary endoscopic impression was concerning for malignancy and multiple biopsies were obtained. Pathology report revealed an acute focal colitis with an aphthous ulcer and few non-necrotizing granulomas. Given incongruity in pathology findings, a sigmoidoscopy was performed, and biopsy findings again revealed granulomatous inflammation as well as 2 small acid-fast positive structures. The patient underwent QuantiFERON testing which was positive. He reported a childhood exposure to mycobacterium tuberculosis but did not recall receiving treatment. Chest CT scan did not reveal any significant pulmonary findings and Abdominal CT scan did not show additional organ involvement. A definite diagnosis of M. tuberculosis could not be ascertained as biopsied samples were not cultured. Thus, another colonoscopy was performed with emphasis on tuberculosis microscopy and culture. Empiric treatment with RIPE and Azithromycin was started to cover tuberculosis and non-tuberculosis mycobacterium. M. tuberculosis was diagnosed by DNA probe and azithromycin was discontinued. Discussion: Abdominal TB possesses a diagnostic challenge due to its non-specific clinical presentation. When intestinal involvement is present, abdominal pain, weight loss, and changes in bowel habits are the most common manifestations. Endoscopically, it can mimic Crohn’s Disease given its ulcerative nature as well as malignancy due to a hyperplastic reaction occasioning an inflammatory mass in the lumen. In the intestines it frequently leads to stricture formation resulting in bowel obstruction. Abdominal TB is generally responsive to standard anti-tuberculous drugs and has shown significant resolution of symptoms in cases of tuberculous strictures. High clinical suspicion is necessary to ensure early diagnosis and treatment leading to favorable outcomes.