Late Pulmonary and Lymph Node Recurrence 14 Years after Curative Resection of Incidentally Diagnosed Appendiceal Adenocarcinoma with Hepatic Metastasis.

INTRODUCTION

Primary appendiceal adenocarcinoma is a rare malignancy, frequently diagnosed incidentally after appendectomy performed for suspected acute appendicitis. Long-term recurrence after curative resection, particularly presenting as an isolated pulmonary metastasis, has rarely been reported.

CASE PRESENTATION: A 35-year-old man underwent emergency appendectomy for acute appendicitis. Postoperative pathology revealed appendiceal adenocarcinoma (pT3N1bM0, stage IIIB). Subsequent right hemicolectomy with D3 lymph node dissection revealed a synchronous hepatic metastasis; simultaneous partial hepatectomy of segment 8 achieved R0 resection, upstaging the disease to pT3N1bM1a, stage IVA (Union for International Cancer Control/American Joint Committee on Cancer 8th edition). Adjuvant chemotherapy with modified folinic acid, fluorouracil (5-FU), and oxaliplatin (modified regimen) was administered. The patient remained recurrence-free for 5 years and was discharged from regular surveillance. Fourteen years and 3 months after the initial operation, he presented with a new cough. Imaging revealed a 10-cm mass in the right lower lung lobe and multiple lymph node metastases. CT-guided biopsy confirmed metastatic adenocarcinoma consistent with the primary appendiceal origin. The patient received first-line S-1 plus oxaliplatin with bevacizumab, followed by second-line capecitabine plus irinotecan with bevacizumab, with ongoing partial responses observed at the time of this report.

CONCLUSIONS

This case represents an exceptionally rare instance of late pulmonary and multiple lymph node metastases from appendiceal adenocarcinoma occurring 14 years after curative resection, even in the setting of initial hepatic metastasis. It highlights the biological diversity of appendiceal adenocarcinoma and underscores the potential need for extended oncological surveillance beyond the standard 5-year period in high-risk patients.