Malignancy Meets Mycobacterium: Diagnostic Dilemma in a Rare Coexistence of Rectal Adenocarcinoma and Tuberculosis

Rectal tuberculosis is a rare manifestation of extrapulmonary tuberculosis, and its coexistence with adenocarcinoma is rarer. We are reporting a 30-year-old male presenting with perianal region pain and anal discharge for 1 month. His clinical examination showed multiple anal fistulae with hard nodular growth just 3–4 cm above the anal verge. Imaging studies revealed a large lower rectum lesion infiltrating surrounding tissue with multiple fistulae extending into the gluteal region. Thus, raising a suspicion of co-existing anorectal tuberculosis with rectal carcinoma. Further, evaluating it, it was evident that both tuberculosis and adenocarcinoma were infiltrating the rectum and were far more advanced than the clinical picture. Planning treatment was challenging due to overlapping toxicities of anti-tuberculosis therapy and neoadjuvant chemotherapy. The patient was placed under close surveillance for adverse effects and treatment response. This case emphasises the importance of early recognition of dual pathologies to guide effective individualised treatment in regions endemic for tuberculosis.