# Histopathologic and molecular diagnosis of gastrointestinal tuberculosis in an immunocompetent patient: case report

## TL;DR

This case report describes a rare instance of gastrointestinal tuberculosis in an immunocompetent patient, diagnosed through histopathology and staining techniques.

## Contribution

The novelty lies in presenting a rare case of GI TB in an immunocompetent individual with nonspecific symptoms.

## Key findings

- The patient tested positive on an interferon-gamma release assay.
- Biopsies showed acid-fast bacilli and non-caseating granulomas, confirming GI TB.
- The case emphasizes the need for high suspicion of TB in unusual presentations.

## Abstract

Gastrointestinal tuberculosis (GI TB) is an extrapulmonary manifestation of infection with the bacterium Mycobacterium tuberculosis. While GI TB was once considered a rare entity, it has increasing prevalence with the use of immunosuppressive treatments. Diagnosis can be challenging as GI TB can be misdiagnosed as other primary etiologies.

Here, we present a case of GI TB in which the patient was immunocompetent and presented with nonspecific symptoms, and an interferon-gamma release assay, which was positive. Subsequent biopsies were performed of the ascending colon, all showing positivity on acid-fast bacilli (AFB, Ziehl-Neelsen) and Fite stains, along with non-caseating granulomas on histopathologic review.

In the presented case, the patient is immunocompetent. GI TB was diagnosed after histopathologic examination of colonic biopsies. This highlights the importance of having a high index of suspicion for unusual presentations of tuberculosis, especially in patients who come from endemic areas or who might have been exposed recently.