Adenomyomatosis of the gallbladder is considered an acquired pathologic condition that affects adults.
References
Zani A, Pacilli M, Conforti A, Casati A, Bosco S, Cozzi DA. Adenomyomatosis of the gallbladder in childhood: report of a case and review of the literature. Pediatr Dev Pathol. 2005 Sep-Oct;8(5):577-80. PMID: 16211444