Groove pancreatitis mimicking duodenal malignancy with gastric outlet obstruction: successful conservative management to avoid unnecessary pancreaticoduodenectomy.

Groove pancreatitis (GP) is a rare focal form of chronic pancreatitis that frequently mimics pancreatic head or duodenal malignancy, often leading to unnecessary pancreaticoduodenectomy. We report the case of a 47-year-old man with heavy alcohol use who presented with severe gastric outlet obstruction (GOO) due to a mass-like duodenal lesion. Clinical, endoscopic, and radiologic features initially suggested primary duodenal malignancy. However, characteristic imaging, negative biopsies, and multidisciplinary review confirmed segmental GP. The patient achieved complete resolution of GOO and the duodenal lesion within 7 days using conservative management alone (alcohol cessation, nasogastric decompression, proton-pump inhibitors, pancreatic enzymes, and nutritional support). This unusually rapid and morbidity-free response highlights that, when malignancy is reliably excluded, pragmatic conservative therapy can safely prevent major pancreatic resection and its associated costs. Greater awareness of GP and early multimodal assessment can reduce overtreatment in ambiguous pancreaticoduodenal masses.