We present the case of a 68-year-old male, with no history of interest and asymptomatic from a digestive point of view. He was referred to the outpatient gastroenterology department for presenting normocytic anaemia and a positive faecal occult blood test (FOBT). The rest of the blood tests and the physical examination showed no findings of interest. Colonoscopy showed an ulcerated lesion at the level of the cecum, in front of the ileocaecal valve, compatible with malignant neoplasia, from which multiple biopsies were taken. These showed ulcerated tissue with no tumour cells visible. In view of the suspected diagnosis, the study was completed with a CT scan, which showed thickening of the wall of the cecum and ascending colon with no evidence of lymph node or distant involvement. Tumour markers were normal. Given the negativity found in the samples, it was decided to repeat the colonoscopy, and biopsies were taken again, which were also negative for malignancy. The biopsies taken at the first colonoscopy were reviewed and showed granulomas with the presence of multinucleated giant cells and mycobacterial bacilli with Ziehl Nielsen staining.

The patient was referred to the outpatient pulmonology department, although he had no respiratory symptoms. Mantoux test was negative, but Quantiferon® was positive (value: 5.12). Chest X-ray showed a reticulonodular infiltrate in both upper fields. Sputum was collected, which was not bacilliferous, and samples were sent for culture, which were negative. PCR of the colon samples was also negative. Standard antituberculosis treatment was started and the clinical course was good. Six months after the end of treatment, a follow-up colonoscopy was performed, which was normal.

