Coexistence of rectal adenocarcinoma and rectal and lymph node tuberculosis: a case report with a limited narrative review

Background Rectal cancer concurrent with regional tuberculosis is a rare clinical entity. Due to its similar clinical symptoms and imaging features, it is frequently misdiagnosed, which profoundly complicates patient management. Case presentation A 72-year-old man with a history of pulmonary tuberculosis presented with three months of intermittent hematochezia and tenesmus. Because the patient self-reported the tuberculosis as cured and initial imaging showed no active pulmonary or evident extrapulmonary lesions, preoperative molecular tuberculosis screening was not initiated. Preoperative imaging and biopsy confirmed rectal adenocarcinoma, alongside clinically suspected (but not histologically proven) pulmonary metastases. After neoadjuvant chemoradiotherapy, further chemotherapy was halted due to severe myelosuppression. A Hartmann procedure was performed after stable disease was confirmed. Postoperative pathology showed rectal adenocarcinoma with no lymph node metastasis (0/24) but unexpectedly revealed granulomatous inflammation in lymph nodes and rectal tissue. TB DNA PCR was positive, providing molecular evidence supporting concurrent tuberculosis. The patient developed postoperative anal discharge and a clinically suspected tuberculosis-related presacral infectious process, which improved after local irrigation and systemic anti-tuberculosis therapy. At one year, there was no tumor recurrence or new tuberculosis. Conclusion In patients with a history of pulmonary tuberculosis who present with rectal cancer, the possibility of concurrent rectal and lymph node tuberculosis should be carefully considered. This case highlights the significant diagnostic overlap between these conditions, the high risk of delayed tuberculosis recognition, and its critical impact on postoperative management. Maintaining a high index of suspicion and utilizing comprehensive pathological and molecular evaluations are essential for accurate differential diagnosis and optimized patient care.