Gastric Large-Cell Neuroendocrine Carcinoma Presenting as Perforation Peritonitis: a Rare Case Report

Abstract

Gastric neuroendocrine carcinomas (GNECs) are rare tumors characterized by an aggressive clinical course, rapid progression, metastatic dissemination, and poor prognosis. Due to overlapping radiological features and small pre-operative biopsy specimens, they are frequently misdiagnosed as adenocarcinoma in the pre-operative period. These tumors are generally asymptomatic or present with non-specific symptoms like epigastric pain or discomfort, weight loss, and loss of appetite. However, GNECs presenting as perforation peritonitis are rarely reported in the literature. A 60-year-old man presented to the emergency department with complaints of pain upper abdomen with loss of weight and appetite for four months. He had an endoscopic biopsy report suggestive of antral growth reported as poorly differentiated adenocarcinoma. Radiological investigations were notable for the presence of a malignant lesion in the stomach with perforation. Subtotal gastrectomy with D1 lymph node resection was done. Specimen pathology confirmed poorly differentiated high grade large cell neuroendocrine carcinoma. This article emphasizes the importance of considering GNEC as a differential diagnosis for gastric adenocarcinoma despite overlapping radiological features and challenges with pre-operative diagnosis due to its aggressive nature and to allow for appropriate management.