Abstract
RATIONALE: Pancreatic ductal adenocarcinoma (PDAC) is the main type of pancreatic cancer with a poor prognosis. Rectal metastasis after radical resection of PDAC is comparatively rare, and the understanding of such cases is currently not unified. This study presents the entire process of diagnosis and treatment of a patient with PDAC metastasized to the rectal. We propose the viewpoint of exploring potential biomarkers or establishing effective predictive models to assist in the clinical decision-making of such cases. PATIENT CONCERNS: We present the case of a 71-year-old man with slight abdominal distension and dull pain. He underwent surgical treatment for a malignant tumor of the pancreatic body, which was discovered through computed tomography and magnetic resonance imaging examinations. Nine months after the pancreatectomy, a rectal mass was identified by digital rectal examination and diagnosed as a malignant lesion through a puncture biopsy. After a multidisciplinary joint consultation, the patient underwent radical surgery. It was later confirmed as rectal adenocarcinoma based on postoperative pathological results. DIAGNOSIS: The pathological result after pancreatic surgery was PDAC, which had invaded the peripheral nerves and abdominal arteries. A diagnosis of rectal metastasis was determined ultimately by combining with the medical history and immunohistochemical staining results. INTERVENTIONS AND OUTCOMES: Treatment of the PDAC included laparoscopic resection of the body and tail of the pancreas combined with splenectomy, and postoperative systemic chemotherapy. In addition, treatment of the rectal metastasis included laparoscopic radical resection and postoperative systemic chemotherapy. The patient's current living condition was good. LESSONS: As a rare metastatic site of PDAC, rectal metastasis should be avoided because of misdiagnosis and missed diagnosis. Surgical resection is still an effective treatment strategy for localized pancreatic tumors and isolated metastases. Furthermore, the mining of potential biomarkers or the establishment of predictive models for pancreatic cancer and its metastases may contribute to better clinical decision-making in the future.