Rectal tuberculosis: the great mimic.

agnostic challenge in the absence of pul− monary infection. Gastrointestinal TB can involve any part of the alimentary tract from the mouth to the anus, the dis− tal ileum being the most common site [1]. Lesions above and below this site are rare. A 72−year−old gentleman complaining of constipation, abdominal pain, and a 2− month history of loss of appetite and weight loss was referred to our gastroen− terology department. Examination revealed pallor; vital signs including pulse, blood pressure, and re− spiratory rate were within normal limits. Abdominal examination demonstrated tenderness in the left iliac fossa, but no mass could be palpated. Digital rectal ex− amination revealed a hard, palpable, fixed mass around 7 cm from the anal verge. Examination of other systems gave unre− markable findings. On the basis of the history and clinical findings a provisional diagnosis of rectal carcinoma was made. Abdominal ultrasonography and chest radiography did not show any abnormali− ty. Colonoscopy showed an irregular, ul− cerated, nodular mass in the rectum around 1.5 cm in size (l" Figure 1) while the rest of the colon appeared normal. Histopathological investigation revealed chronic inflammatory cells in the mucosa showing a number of scattered epithe− lioid histiocytic granulomas with central necrosis (l" Figure 2), and Ziehl±Neelsen staining showed numerous acid−fast ba− cilli (l" Figure 3). On the basis of these findings rectal tuberculosis was diag− nosed, and the patient was started on an antituberculosis treatment regime with regular follow−up. Intestinal TB commonly occurs in the sec− ond and third decades of life; only 2% of cases present after the age of 60 years [2].Only half of the patients have an ab− normality in the chest radiograph or have active pulmonary tuberculosis [3]. Between 30 % and 50 % of intestinal cases reported did not reveal acid−fast bacilli on Ziehl±Neelsen staining [4]. This case shows that tubercular involve− ment of the rectum is rare. It can closely mimic carcinoma of the rectum, and its diagnosis can be challenging.