Adenomyomatous Hyperplasia of the Vaterian System: The Hidden Culprit Behind Whipple Procedures.

IntroductionAdenomyomatous hyperplasia (AH) of the Vaterian system is a rare benign lesion, often clinically mistaken for carcinoma and leading to unnecessary Whipple surgery.MethodsIn this multicentre cohort, Whipple pancreaticoduodenectomy specimens were identified and operated on with a clinical diagnosis of ampullary tumor, which on histological examination, however, showed AH, collected over 3 years (2022-2024). In this retrospective observational study, we analyzed the clinico-radiological and histological details of 12 of such patients and described them here.ResultsIn these 12 patients with pancreaticoduodenectomy, the mean age was 51.7 years (range 29 to 63 years) with a male-to-female patient ratio of 9:3. Although abdominal pain was the most common presentation (11/12 patients); obstructive jaundice occurred in two. The preoperative imaging revealed common bile duct dilatation (11/12) and double duct sign (6/12), with the suspicion of carcinoma in all. Grossly, the lesions measured 0.4 to 4.3 cm (median 1.4 cm), six centered on the ampulla, others extending to the pancreatic head or the distal bile duct. Microscopy showed bland mucous glands, smooth muscle, and fibroblasts; immunohistochemistry confirmed keratin 7, MUC6, MUC5AC, and actin positivity. Ki-67 index was low. No recurrences occurred during 6-48 months follow-up.ConclusionsClinicoradiologically, ampullary AH mimics ampullary malignancy. However, AH should be considered in the clinicopathologic differential diagnosis of ampullary lesions.