RESUMEN
Heterotopic or ectopic tissue is a congenital anomaly defined as the presence of the tissue outside its normal location. This tissue is usually discovered incidentally and may be asymptomatic or may present with non-specific gastrointestinal (GI) symptoms. Two types of heterotopic tissues, pancreatic and gastric, predominantly occur in the GI tract. The frequency of ectopic pancreas found in autopsy studies is approximately 0.5%-13.7%. Heterotopic pancreatic tissue can be located anywhere along the GI tract; the most common sites are the stomach (27.5%), duodenum (25.5%), colon (15.9%), esophagus, and Meckel`s diverticulum. It has been found in approximately one per 500 surgical procedures involving the upper GI tract. It can also occur in the gallbladder, biliary tract, spleen, liver, omentum, mesentery, lung and pelvis. Likewise, heterotopic gastric mucosa can occur anywhere along the GI tract yet its most common locations are different from those of heterotopic pancreatic tissue. In this paper we present heterotopy characteristics in particular locations. Gastric or pancreatic heterotopy, although rare, should be taken into consideration in differential diagnosis of unexplainable abdominal pain, bleeding from the GI tract or weight loss. Once heterotopy has been detected, appropriate treatment can be implemented which will reduce the risk of complications.