P1656 - A Case Report of Gastric Mixed Neuroendocrine-Non-Neuroendocrine Neoplasms Requiring Endoscopic Submucosal Dissection and Subsequent Total Gastrectomy

Esli Medina-Morales, MD¹, Riya Sutariya, BA², Mohamed Ismail, DO¹, Ritik M. Goyal, MBBS¹, Yazan Abboud, MD¹, Bryan Medina-Morales, MD³, Harold Benites-Goñi, MD^4
1Rutgers New Jersey Medical School, Newark, NJ; ²New Jersey Medical School, Iselin, NJ; ³Universidad San Martin de Porres, Lima, Lima, Peru; ⁴Universidad Peruana Cayetano Heredia, Lima, Lima, Peru

Introduction: Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are rare tumors characterized by the presence of both neuroendocrine and non-neuroendocrine components. They can occur in various organs, particularly the gastrointestinal tract, and pose diagnostic and therapeutic challenges. We herein report the case of a patient diagnosed with MiNEN who was initially underwent endoscopic submucosal dissection (ESD) but later required total gastrectomy with regional lymph node showing neuroendocrine tumor involvement (NET).

Case Description/Methods: A 63-year-old male was referred to Rebagliati Hospital, Lima, Peru, with a gastric lesion suspicious for early gastric cancer. A previous biopsy had indicated adenocarcinoma. Esophagogastroduodenoscopy revealed a 25 mm semi-pedunculated lesion on the anterior wall of the upper body of the stomach. During the endoscopic evaluation, a short and thick stalk was noted (Figure 1a). Dynamic assessment showed the absence of a non-extension sign. Computed tomography revealed no lymph node involvement or distant metastasis. After a multidisciplinary meeting, the decision was made to perform an ESD for diagnostic and potentially curative purposes. Histological examination after resection revealed a 22 x 20 mm, type 0-Isp, mixed MiNEN, consisting of 60% tubular adenocarcinoma (tub2) and 40% NET, classified as pT1b (submucosal invasion of 1500 µm, pUL0, Ly0, v0, pHM0, pVM0) (Figure 1b). Immunostaining was positive for chromogranin A in the NET component (Figure 1c). The Ki67 index of the NET component was 2%. Subsequently, a total gastrectomy with lymph node dissection was performed. During surgery, numerous nodules suspicious for lymph node metastasis were identified. The resected specimen showed no histological remnants of cancer, but regional lymph node involvement due to the neuroendocrine tumor was evident. The patient is currently under follow-up.

Discussion: This case highlights the complexity of diagnosing and managing mixed MiNENs. Despite initial treatment with ESD appearing curative, the presence of regional lymph node involvement necessitated a total gastrectomy. The neuroendocrine component's behavior, evidenced by lymph node metastasis, underscores the importance of comprehensive evaluation and follow-up in patients with MiNENs to address potential metastatic risks and ensure optimal treatment outcomes



Disclosures:


Esli Medina-Morales, MD¹, Riya Sutariya, BA², Mohamed Ismail, DO¹, Ritik M. Goyal, MBBS¹, Yazan Abboud, MD¹, Bryan Medina-Morales, MD³, Harold Benites-Goñi, MD⁴. P1656 - A Case Report of Gastric Mixed Neuroendocrine-Non-Neuroendocrine Neoplasms Requiring Endoscopic Submucosal Dissection and Subsequent Total Gastrectomy, ACG 2024 Annual Scientific Meeting Abstracts. Philadelphia, PA: American College of Gastroenterology.