Two Cases of Mixed Neuroendocrine Carcinoma and Non-neuroendocrine Neoplasm (MiNEN) of the Colon with Good Outcomes

Abstract

Two cases of mixed neuroendocrine carcinoma and non-neuroendocrine neoplasm (MiNEN) are presented. A 50-year-old woman noticed an abdominal mass. Transverse colon cancer [cT3N2bM0 cStage IIIc] was diagnosed by computed tomography and colonoscopy. Right hemi-colectomy and lymphadenectomy were performed. Pathological examination showed combined features of adenocarcinoma and neuroendocrine carcinoma. The pathological diagnosis was MiNEN, pT3N0M0 pStage IIa. The patient received 8 courses of adjuvant CapeOX chemotherapy. At 12-month follow-up, the patient was well with no evidence of recurrence. A 72-year-old man was found to be positive for fecal occult blood. Colonoscopy showed a sigmoid colon polyp. The patient underwent endoscopic mucosal resection (EMR) of the polyp. The pathological diagnosis was MiNEN with deep submucosal (SM) invasion. Based on these findings, additional resection (laparoscopic sigmoidectomy and D3 lymph node dissection) was performed. The pathological diagnosis was MiNEN, pT1bN1M0 pStage IIIa. However, the patient did not wish to receive chemotherapy. At 60-month follow-up, the patient was well, with no evidence of recurrence. Although the prognosis of MiNEN is quite poor, multidisciplinary treatment resulted in a relatively good course. These cases are reported with a review of the literature.