[Heterotopic gastric mucosa of the rectum. Case report with literature review].

Heterotopic gastric mucosa is a rare finding in the rectum. Apart from two other hypotheses, a misdifferentiation of entodermal stem cells is the most widely accepted aetiopathogenetic assumption today. Due to acid secretion, the lesions predominantly manifest with hematochezia. Therapeutic options include medicinal therapy and particularly (endoscopic) removal. From the pathologist's point of view a careful evaluation is required also in terms of basically possible dysplastic or malignant changes.