Colonic tuberculosis: a case report

Aim Colonic tuberculosis is rare. It accounts for 2–3% of abdominal tuberculosis. Clinical, radiological and endoscopic features are nonspecific. The diagnosis must be considered in front of chronic abdominal pain, vesperal fever and weight loss with on colonoscopy the presence of nodules or ulcers. The diagnosis is made on pathological findings. Case report We report a case of an 82-year-old female patient with the diagnosis of colonic tuberculosis. The diagnosis were suspected on clinical presentation: chronic abdominal pain, fever and weight loss. The colonoscopy showed a nodular aspect of the left and sigmoid colonic mucosa and the pathology examination of the multiple biopsy specimens showed an epithelioid and gigantocellular granulomas with caseous necrosis. Conclusion In front of a nonspecific clinical and endoscopic aspects, multiples colonic biopsies are mandatory to rule out differential diagnosis and confirm colonic tuberculosis.


Discussion
The incidence of extrapulmonary tuberculosis has increased in the last few years, even in developed countries, due to the increased incidence of HIV infection, making individuals vulnerable to tuberculosis [3].
In developing countries, it remains endemic despite the availability of an effective antituberculosis chemotherapy and pasteurized milk. In developed countries, the main risk factors are HIV infection, chronic renal disease and immunosuppression with prolonged steroid therapy [4]. Abdominal tuberculosis accounts for 5% of the cases of tuberculosis and 1-3% of them are gastrointestinal [5]. It mainly involves the ileocecal region and the adjoining part of the ascending colon [6]. Colorectal tuberculosis accounts for 11% of all gastrointestinal tuberculosis. The most commonly-affected sites are the transverse colon, the rectum, followed by the ascending colon [2].
Digestive involvement may be primary through direct ingestion of mycobacterium or secondary to highly bacilliferous lung lesions via the hematogenous or lymphatic route [7]. The bacterial agent is most often bovine or human Kokh's bacillus, exceptionally it is mycobacteria in immunocompromised subjects [7].
Clinical manifestations in colonic tuberculosis are less acute and less specific than the small intestine and the ileocecal localizations and therefore responsible for a delayed diagnosis [8]. Chronic abdominal pain is the most frequent presentation. Others manifestations are weight loss (80%), fever (66%), constipation (40%), ascites (40 to 100%), diarrhea (15%) with sometimes a dysenteric syndrome in the case of rectosigmoid location [9]. Sometimes, it can cause recurrent subacute intestinal obstruction episodes [6].
The most frequent colonoscopic features are transverse or linear ulcers or nodules [10]. Our patient had multiples nodules. Sometimes, a white fluid is extruded on biopsy [11], as it was the case in our patient.
Radiographic findings may help the diagnosis in case of pulmonary location but only quarter of patients with intestinal tuberculosis have evidence of active pulmonary tuberculosis [10].
Adenopathies are the most common site of extra-pulmonary tuberculosis. However, additional tests, such as physical examination and an abdominal CT did not detect any adenopathies in our patient. Searching of other sites isn't systematic.
The diagnosis is made on histopathological data showing granulomas with epitheloid cells and Langhans' giant cells with caseation and acid and alcohol-fast bacilli [12].
The presentation often mimics a colorectal cancer or Crohn's disease which are the mainly differential diagnosis [2,13]. Pathological data showing granulomas with caseation is specific to tuberculosis and eliminate other diagnosis.
Our case report emphasizes that multiple biopsy specimens and pathological data showing granulomas with caseation are necessary for the diagnosis of colonic tuberculosis in front of a colonic lesion. The main differntial diagnoses to rule out are neoplasia and Crohn's disease.

Conclusion
Colonic tuberculosis is rare with nonspecific clinical, radiological and endoscopic features. However, the diagnosis must be considered in patients with chronic abdominal pain and weight loss.

Summary points
• Clinical and radiological features of colonic tuberculosis are nonspecific. The diagnosis must be considered in case of abdominal chronic pain and general symptoms. • The mainly differential diagnosis are colorectal cancer or Crohn's disease.
• In front of a nonspecific clinical and endoscopic aspects, multiples colonic biopsies are mandatory to rule out differential diagnosis and confirm colonic tuberculosis.

Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript.