Gastric Hamartomatous Inverted Polyp: A Rare Subepithelial Lesion With Unusual Endoscopic Ultrasonographic Features

Gastric hamartomatous inverted polyp (GHIP) is a rare benign gastric lesion that may mimic other subepithelial tumors, making preoperative diagnosis challenging.We report the case of a 61-year-old man investigated for persistent epigastric pain, unintentional weight loss, and altered bowel habits.Upper gastrointestinal endoscopy revealed a well-circumscribed subepithelial lesion in the gastric fundus, initially suspected to be a gastrointestinal stromal tumor (GIST).Endoscopic ultrasonography (EUS) demonstrated a 25 mm, predominantly hyperechoic submucosal lesion with mild internal heterogeneity and small anechoic areas, favoring a gastric lipoma.Endoscopic ultrasound-guided sampling and deep bite-on-bite biopsies revealed dilated and architecturally distorted fundic-type glands within the submucosa, without cytological atypia.Immunohistochemical staining was positive for pepsinogen and MUC6, supporting the diagnosis of GHIP.This case highlights the importance of considering GHIP in the differential diagnosis of atypical hyperechoic gastric subepithelial lesions and emphasizes the complementary roles of EUS and histopathological examination.