Late-Onset Para-Aortic Lymph Node Recurrence 11 Years after Resection of Pancreatic Cancer: Histological Reassessment Revealed Neuroendocrine Differentiation Amenable to Surgical Resection.

introductionWhile para-aortic lymph node recurrence may occur after curative resection for pancreatic ductal adenocarcinoma (PDAC), it is rarely seen as a late recurrence and is usually treated with systemic chemotherapy. In contrast, recurrence of pancreatic neuroendocrine neoplasms (Pan-NENs) can occur more than a decade after surgery and may be amenable to surgical resection. Although immunohistochemical techniques have significantly enhanced the diagnostic distinction between PDAC and Pan-NEN, challenges remain, particularly in older cases. CASE PRESENTATION: A 77-year-old man underwent distal pancreatectomy for pancreatic body cancer 11 years prior, initially diagnosed as PDAC based on glandular morphology, and received adjuvant S-1 chemotherapy. Surveillance ended after 5 years without recurrence. Eleven years after surgery, imaging performed during evaluation for elevated prostate-specific antigen revealed a 16-mm para-aortic lymph node enlargement. CT-guided biopsy showed neuroendocrine morphology with chromogranin A and synaptophysin positivity, consistent with neuroendocrine tumor (NET). Retrospective histological review of the original surgical specimen revealed previously unrecognized NET-G2 components (Ki-67, 5.0%). Surgical resection of the para-aortic and mesenteric lymph nodes was performed, and pathology confirmed NET-G2 metastases (Ki-67, 6.7%). The patient recovered uneventfully and remains recurrence-free at 7 months postoperatively under active surveillance.

conclusionsThis case highlights the importance of tissue diagnosis when late-onset recurrence is observed in patients with a prior diagnosis of PDAC. It also underscores the potential for extremely delayed recurrence in Pan-NENs and the importance of long-term surveillance. For patients presenting with isolated distant recurrence long after initial treatment for PDAC, biopsy and pathological re-evaluation should be considered to ensure appropriate therapeutic decision-making.