DISSEMINATED TUBERCULOSIS AS A DIFFERENTIAL DIAGNOSIS OF INFLAMMATORY BOWEL DISEASE IN AN IMMUNOCOMPETENT PATIENT

Tuberculosis (TB) is an infectious disease that can affect multiple organs and mimic inflammatory bowel diseases, especially in immunocompetent patients. We report a 47-year-old man, a merchant from Caxias do Sul (RS), previously healthy, who in February 2025 sought care with anal pain, hemopurulent drainage, fecal incontinence, fever, chills, hyporexia, and weight loss. He was hospitalized and started amoxicillin with clavulanate, with no improvement after three days. Transferred to the General Hospital, the proctology service confirmed a perianal fistula and performed fistulectomy with a seton drain, with discharge for outpatient antibiotic therapy. On return, the patient worsened and underwent elective colonoscopy with findings suggestive of Crohn’s disease. Two days later, he returned to the emergency department with fever and persistent anal pain, receiving ciprofloxacin and metronidazole empirically; however, he continued with purulent anal secretion. Abdominal CT incidentally identified a “tree-in-bud” pattern in the lung bases, suggestive of a granulomatous process, confirmed by chest CT. He denied respiratory symptoms and contact history. Serologies for HIV, syphilis, and hepatitis were negative. Admitted to the Internal Medicine ward, sputum was collected for acid-fast bacilli (AFB) testing and the standard TB regimen was started (RHZE: rifampicin, isoniazid, pyrazinamide, and ethambutol). Smear microscopy confirmed the TB diagnosis ‒ AFB ++. Gastroenterology performed an intestinal mucosa biopsy, with identification of confirmatory findings by pathology and immunohistochemistry. The patient evolved well, without adverse reactions, and was discharged for outpatient follow-up. The report reinforces that TB should be considered in the differential diagnosis of inflammatory bowel disease, even in immunocompetent patients and without respiratory symptoms, highlighting the importance of broad investigation, including imaging exams and detailed microbiological confirmation.