Introduction
Gastric heterotopia has been described anywhere throughout the gastrointestinal tract and is the most reported epithelial heterotopia.1,2 Gastric heterotopia occurs when gastric mucosa migrates to the wrong section of the GI tract during early organogenesis. This condition can be asymptomatic or symptomatic, depending on the elaboration of gastric acid and the effects on surrounding tissues. Its symptomology can also lead to unusual complaints whose etiology is only elucidated after biopsies.
Heterotopic gastric mucosa is classified as either congenital or acquired. Congenital heterotopia is due to heteroplasia which is an error in the final positioning of endodermal stem cells throughout the course of organogenesis. Acquired gastric heterotopia is a metaplastic process, an erroneous differentiation of pluripotent cells of damaged epithelium. Histologically, oxyntic mucosa suggests gastric heteroplasia over metaplasia.2
Depending on its location, gastric heterotopia can result in various symptoms. Nonspecific abdominal symptoms can include bloating, abdominal discomfort, cramping, and changes in bowel habits. It has also presented with acute and chronic hematochezia. If the lesion is present in the anorectal area, it can also result in pruritus ani, burning, tenesmus, and anal pain.3
Rectal gastric heterotopia is exceedingly rare. Since its first reporting in the 1930's, only around one hundred cases have been described.2
Treatment for symptomatic patients may be done with histamine-2 receptor blockers as the symptoms are due to the presence of acid-producing cells in a foreign area.4 However, the most definitive treatment is surgical or endoscopic extirpation of the lesion.3
Patients presenting with symptomatic gastric heterotopia, such as nonspecific abdominal or anorectal pain, are more frequently in the pediatric population. This younger symptomatic population also has a higher prevalence of gastric heterotopic related complications, such as bowel perforation and ulcer or fistula formation.3 These cases have been associated with higher rates of oxyntic cells, indicating that acid production is the root cause of the complication. This supports treatment with H2- receptor antagonists or proton pump inhibitors which can provide relief of symptoms.5
Report of Case
We present a case of rectal gastric heterotopia in the rectum which originally appeared as a spread-out rectal lesion with heaped-up borders during an initial routine colonoscopy screening in a 56-year-old patient who was completely asymptomatic. The pathology report diagnosed the lesion as gastric heterotopia.
Results
Evaluation of the tissue demonstrated oxyntic-type gastric mucosal tissue, including glands lined by parietal cells, chief cells, and mucous cells. Additionally, gastric foveolae, intermingled with colonic tissue in the same fragments was also noted.
Discussion
The histology report suggests that the patient had a congenital gastric heterotopic lesion in her rectum. This was evident by the oxyntic-type gastric mucosal tissue, including glands lined by parietal cells, chief cells, and mucous cells, as seen in Figure 1. The acquired form of the disease is more commonly indicated by the presence of only gastric foveolae intermingled with indigenous tissue.
An increase of incidental diagnoses of gastric heterotopia in the rectum and anus has been seen, which most probably can be explained due to increased colonoscopies nationwide for colorectal cancer screening within the past decade.
Gastric heterotopia may have malignant potential. However, the rate at which it can convert to malignancy is unknown and requires further research.6
Conclusion
Gastric heterotopic lesions can occur throughout the gastrointestinal system, with lesions in the rectum being exceedingly rare. This condition can be asymptomatic or symptomatic, depending on the elaboration of gastric acid and the effects on surrounding tissues. The presence of this lesion in an unfamiliar location can surprise the clinician with an unusual-appearing lesion. Its symptomology can also lead to unusual complaints whose etiology is only elucidated after biopsies. The complete extirpation of these lesions would be curative, but the symptoms can be managed with antacid therapy. With the increased numbers of colonoscopies due to increased efforts nationwide to perform colorectal cancer screening, reports of gastric heterotopia should rise. The potential for these lesions to become malignant needs to be further studied.