Regional metastasis in multiple type I gastric neuroendocrine tumors: a case report

Background. Gastric neuroendocrine tumors (gNETs) are rare neoplasms accounting for less than 3 % of all gastric tumors. Type 1 gNETs are the most common tumors associated with autoimmune gastritis and characterized by a low risk of metastasis and a favorable prognosis. Case description. We report a rare case of regional metastasis of multiple type I gNETs in a 35-year-old male patient with a history of autoimmune atrophic gastritis. Endoscopic ultrasonography revealed more than 20 subepithelial lesions measuring up to 1.5 cm in the gastric fundus and body, with the largest involving the submucosal layer. Large tumors were excised using endoscopic submucosal dissection (ESD). Histological and immunohistochemical studies revealed well-differentiated gNETs G1 (Ki67 – up to 2 %) with invasion into the submucosal layer and signs of incomplete removal of the tumor (pT1b L1V0R1). The patient underwent laparoscopic gastrectomy with D2 lymph node dissection. Histological examination of the surgical specimen revealed subcapsular metastasis of gNET in one of the removed lymph nodes with invasion of its capsule, but no tumor cell spread beyond the node. The patient did not receive any specific therapy pre- or postoperatively. Conclusion. This clinical case demonstrates that even with a favorable immunophenotype of gNETs type I, a tumor size greater than 1.0 cm and invasion into the submucosal layer indicate an increased risk of lymph node metastasis. This case confirms the validity of current clinical guidelines that consider these factors as key criteria for making decisions on surgical treatment with lymph node dissection.