Heterotopic Pancreas : Microscopic

Comments:
Microscopic Features: Heterotopic pancreas consists of an admixture of pancreatic acini, ducts, and islet cells in varying proportions, based on which it is subdivided into four Heinrich types:

type I - total heterotopia; all cell types present; resembles normal pancreas; most common type
type II - canalicular heterotopia, ducts only; consists of lobular arrangement of small ducts and ductules surrounded by smooth muscle fascicles; resembles adenomyoma
type III - exocrine heterotopia; acinar tissue only
type IV - endocrine heterotopia; islet cells only; may resemble neuroendocrine tumor; rare

Given the location of heterotopic pancreatic tissue in the submucosa and muscularis propria, the superficial biopsies containing only mucosa may not be diagnostic. Immunohistochemical staining for endocrine markers (insulin, glucagon, somatostatin) or pancreatic exocrine markers (trypsin, chymotrypsin, lipase, amylase) is rarely needed for diagnosis.

Image courtesy of: Dr. Farid Azmoudeh-Ardalan, Professor of Pathology, Tehran University of Medical Sciences, Tehran, Iran; used with permission