Heterotopic Pancreas : Microscopic
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 typetype 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. About this image: This image shows heterotopic pancreatic tissue in stomach. Gastric mucosa is on the left, pancreas is on the right, and the black pigmented tissue in the submucosa in the middle is the result of tattoo placed by the endoscopist to mark the site of the lesion for subsequent surgical management. Image courtesy of: Sanjay Mukhopadhyay, MD.