Objective: Staging of colorectal carcinomas is of eminent importance for prognostication and treatment; preoperative distinction between high grade dysplasia, invasion of submucosa (with permigration of the muscularis mucosae MM) and infiltration of muscularis propria (MP) is difficult in biopsies, due to similarities of smooth muscle cells in MM and MP. Smoothelin is a robust marker of the MP in normal colon, not expressed in MM.We analysed it value for distinguishing MP and MM near carcinomas. Objective: Tuberculosis can affect any part of the gastrointestinal tract. Anal localization, in particular, has a very low incidence (0,7 %). Method: A 66 year-old male presented, complaining of perianal pain, constipation, weight loss of 5 kilos the last 4 months and night sweating. Physical examination was normal, except for an ulcerated lesion in the anal region. The patient was submitted to computerized tomography (CT) and incisional biopsy of the lesion. Results: The CT of the chest revealed multiple, scattered, calcified nodules in the upper zones of both lungs and histological examination showed confluent, non-necrotizing, epithelioid granulomas with the presence of Langhans' multinucleated giant cells. Acid-fast bacilli were detected both within the anal lesion and in the sputum. Mantoux test was positive. The patient had a history of pulmonary tuberculosis 40 years ago. A diagnosis of anal tuberculosis was made and the patient was put on a four drug anti-tuberculous regimen. In 6 months the symptoms improved and the perianal lesion healed. Conclusion: A tuberculous origin must be considered when the cause of anal and perianal lesions is unclear. Therefore histological and bacteriological confirmation is essential in order to avoid undue delay in diagnosis and treatment.