adenomyomatous hyperplasia of the gallbladder
Friday 28 September 2007
Histologically 2 types of adenomyomatous hyperplasia were recognized.
The first one is characterized by numerous Rokitansky-Aschoff sinuses (RASs) and is accompanied by smooth muscle hyperplasia and an expanded subserosal layer containing numerous nerve trunks.
The second type is characterized by an extensively fibrotic gallbladder wall with numerous RASs but with few or no smooth muscle bundles and an expanded subserosal layer containing abundant nerve-trunks.
Perineural and intraneural invasion are identified only in the subserosal layer. The lack of p53 reactivity and the very low MIB-1-labeling index provide additional support to the non-neoplastic nature of the lesion.
The pseudoinvasive pattern of the RASs, reactive epithelial atypia, and the perineural and intraneural invasion probably contribute to the erroneous diagnosis of adenocarcinoma or "adenoma malignum."
The mechanism by which the epithelial structures "invade" the perineural spaces and the nerves is unclear.
The migration of the benign glandlike structures into the nerves is related to the production of chemotactic factors or signaling substances and the activation of cell receptors.
Albores-Saavedra J, Keenportz B, Bejarano PA, Alexander AA, Henson DE. Adenomyomatous Hyperplasia of the Gallbladder With Perineural Invasion: Revisited. Am J Surg Pathol. 2007 Oct;31(10):1598-1604. PMID: 17895763