RESUMO
INTRODUCTION: Neuroendocrine tumor (NET) that develops in the right-sided colon is relatively rare. Coexistence of adenocarcinoma and NET is extremely rare, and such cases are called mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN). PRESENTATION OF CASE: Colonoscopy in an 85-year-old woman for an anemia examination indicated laterally spreading tumor-nongranular (LST-NG) in the transverse colon. Colonoscopy and endoscopic ultrasonography (EUS) showed that the depth of the tumor invasion was deep submucosal. The tumor localization was diagnosed as transverse colon close to the hepatic curvature by enema. Computed tomography (CT) showed no obvious lymph node or distant metastasis. Based on these findings, laparoscopic transverse colectomy with D2 lymphadenectomy was performed. Pathologically, most of the tumor was well-differentiated tubular adenocarcinoma, but some solid follicles of polygonal tumor cells with poor nuclear atypia were observed. Immunostaining was positive for synaptophysin and diagnosed as NET G1. This tumor consisted of adenocarcinoma and neuroendocrine tumor, so we diagnosed it as MiNEN and classified the tumor as fT1N0M0 fStage I (TNM Classification of Malignant Tumors, 8th Edition). Since it was an early stage cancer, postoperative adjuvant therapy was not performed. No recurrence has yet been noted. DISCUSSION: Although MiNEN is extremely rare, the detailed pathological specimen observation and diagnosis are important because long-term follow-up after surgery is needed, as is the adequate selection of postoperative adjuvant therapy. CONCLUSION: It is important to elucidate the mechanisms involved in the coexistence of NET and adenocarcinoma and to apply these findings to future medical care.
RESUMO
The present study described the case of a 24-year-old man who was diagnosed with multiple gastric hyperplastic polyps in 2004. Repeated Helicobacter pylori tests were negative, and colonoscopy revealed no specific findings. The patient started taking a proton-pump inhibitor and iron supplements as a result of anemia caused from the occasional bleeding from the polyps. The number and size of the polyps had increased over time. Endoscopic mucosal resection was occasionally performed when bleeding occurred from large polyps. Finally, histological examination revealed that the surface of the polyp had been replaced with well-differentiated adenocarcinoma in 2014. Laparoscopy-assisted total gastrectomy with Roux-en-Y esophagojejunostomy was performed in 2014. The final diagnosis was juvenile polyposis of the stomach with multiple early gastric cancers. Juvenile polyposis of the stomach is a rare disease, and its malignant potential has been reported previously. The present case highlighted the importance of not delaying surgical intervention in cases of juvenile polyposis of the stomach, since it is associated with a high occurrence of gastric cancer.