Duodenal tuberculosis: dig deep to diagnose

Introduction

The duodenum is an uncommon site of tuberculosis (TB) and usually presents with gastric outlet obstruction and constitutional symptoms. We report a case of isolated duodenal TB which was diagnosed using deep well biopsies.

Case report

A 38-year-old woman presented with a history of recurrent vomiting for 3 months, often post-prandial and not bile stained. In fact, the vomitus usually contained undigested food indicating a gastric outlet obstruction. Associated was a decreased appetite, weight loss and low grade fever. There was no history of abdominal pain, jaundice, gastrointestinal bleeding, cough or haemoptysis. Physical examination was unremarkable except for mild pallor. Routine blood investigations were within normal limits except for an anaemia (Hb 8.6 g/dL). She was seronegative for HIV. Computed tomography (CT) of abdomen however showed mural thickening of the second part of duodenum (Figure 1). Initial upper GI endoscopy showed plenty of food residue in the stomach despite a gaping pylorus. The endoscopy was repeated after a gastric lavage and revealed thickened, abnormal folds with ulceration in the duodenum (Figure 2). Initial biopsies showed only chronic inflammation. To obtain deeper specimens, a biopsy upon biopsy (the well technique) was used; this finally revealed the presence of non-necrotising well-formed granulomata (Figure 3). No acid-alcohol bacillus (AAFB) was noted and the polymerase chain reaction (PCR) from the tissue for TB was negative. A chest radiograph was normal but Mantoux was strongly positive (18 × 10 mm). OPEN IN VIEWER

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Figure 2.

Endoscopy showing distorted, thickened and ulcerated folds.

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Figure 3.

Two well-formed non necrotizing granulomas in the lamina propria and submucosa of the duodenum (arrow, H&E, 100X).

The patient was started on anti-tubercular therapy with rifampicin, isoniazid, pyrazinamide and ethambutol. After only 1 month the patient had significant resolution of her symptoms and gained 3 kg of weight. A standard course of treatment for 6 months was advised.

Discussion

TB is a major public health problem especially in low- and middle-income countries. Abdominal TB is one of the more common sites of extrapulmonary TB but duodenal tuberculosis accounts for less than 2% of cases. ¹ The reasons cited for this include the inhibitory influence of gastric acid on mycobacteria, the rapid transit time through the duodenum allowing for a reduced contact time and the relative paucity of lymphoid tissue in the duodenal segment as compared to the rest of the gastrointestinal tract. ² With pre-existing pyloric obstruction from peptic ulceration, the aforementioned factors may fail to prevent TB colonisation. Duodenal TB may itself cause gastric outlet obstruction from intrinsic (mucosal involvement) or extrinsic (lymphadenopathy) compression or a combination of both. ¹ The intrinsic form may be ulcerative, hypertrophic or ulcerohypertrophic and may be complicated by the formation of fistulae or strictures. Duodenal TB may present with symptoms similar to peptic ulceration, namely dyspepsia, abdominal pain, weight loss, upper GI bleeding, but gastric outlet obstruction is the most common presentation. ¹

Traditionally, endoscopy has been thought to have little value in obtaining a histological diagnosis of tuberculosis with yields in the range of 0–10%.^3,4 However, in more recent studies, granulomatous inflammation was demonstrated in 90–100% of patients using a combination of multiple endoscopic biopsies and endoscopic mucosal resection (EMR) although AAFB was rarely demonstrated.^5,6 In our patient we had taken multiple deep biopsies. This involves taking a biopsy upon the site of a previous biopsy, thereby taking deeper tissue. As in the aforementioned studies, stains for AAFB were negative despite the presence of granulomata on histopathology. The use of the ‘well’ technique has been described in ileocaecal tuberculosis to give a good microbiological yield; however its use in gastro-duodenal tuberculosis has not yet been reported. ⁷ Furthermore, it may not be feasible for all endoscopists to perform an EMR but well biopsies are easy to obtain. The management of gastroduodenal tuberculosis is of course with anti-tubercular therapy. Initial balloon dilatation of a duodenal stenosis, if present, may be warranted.

A high index of clinical suspicion is required to clinch the diagnosis owing to the absence of specific clinical, laboratory, imaging or endoscopic findings. This case also re-affirms the old clinical adage that rare presentations of common diseases are more likely than common presentations of rare, exotic diseases.