Heterotopic Gastric Mucosa at the Duodenojejunal Junction: A Rare Case Report of a Lesion Prone to Misdiagnosis as a Tumor

Inside the human body, the digestive tract is a long, continuous tube, but it is not made of the same material from end to end. Different sections are lined with specialized tissues designed for specific tasks: the stomach produces acid to break down food, while the intestines are built to absorb nutrients without being damaged by that same acid. Occasionally, during early development, a patch of stomach tissue gets misplaced and ends up in the intestine. This condition is known as heterotopic gastric mucosa. While the stomach lining is perfectly suited for the stomach, its presence in the intestine can cause confusion. Because this misplaced tissue looks and behaves like a growth, doctors often worry it might be a tumor, leading to difficult decisions about whether to operate. Understanding how to distinguish a harmless patch of misplaced tissue from a dangerous cancer is a critical challenge in modern medicine, as unnecessary surgery carries significant risks.

A recent report from Jinan Central Hospital details a rare instance of this condition in an 18-year-old woman who had been suffering from bloating and belching after meals for a year. When doctors first examined her, they found a distinct mass at the point where the small intestine begins, a location where such a growth is exceptionally uncommon. Scans showed a well-defined oval shape measuring approximately 5.2 cm by 3.3 cm by 1.9 cm. The mass was pressing into the intestinal passage, narrowing the space available for food to pass through. What made this case particularly tricky was that the mass looked very much like a tumor on the imaging tests. However, the way it enhanced with contrast dye actually argued against the typical appearance of gastrointestinal stromal tumors or lymphoma, both of which are serious cancers. Instead, the mass showed a homogeneous enhancement pattern similar to normal stomach lining, a feature that helped steer the diagnosis away from malignancy.

To get a clearer picture without cutting into the patient, the medical team used a specialized camera that could magnify the surface of the mass. This tool allowed them to see the tiny pits on the tissue's surface, which are characteristic of stomach lining rather than intestinal tissue. A small sample was then taken for microscopic examination. Under the microscope, the tissue revealed a complete stomach structure, including the specific cells that produce stomach acid and enzymes. Crucially, the sample showed no signs of cancer, no abnormal cell growth, and no features of other tumors like ectopic pancreas or neuroendocrine tumors. The diagnosis was confirmed as a large patch of misplaced stomach tissue that had grown into a mass-like shape, rather than a malignant tumor.

Given the location of the mass, the decision on how to treat the patient was complex. The area where the mass was found is a tight corner of the body, surrounded by the pancreas and major blood vessels. Surgical removal in this spot is notoriously difficult and carries a high risk of severe complications, such as leaks or damage to the pancreas. Similarly, attempting to remove the mass through a scope would be technically dangerous due to the risk of perforation. Because the tissue was confirmed to be benign and the symptoms were likely driven by the secretion of gastric acid and pepsin from the misplaced tissue, the doctors chose a conservative approach. They prescribed a medication that reduces stomach acid production to see if it would relieve the discomfort.

Three months after starting this treatment, the patient's symptoms had completely resolved. This outcome suggests that for cases where a patch of misplaced stomach tissue is confirmed to be non-cancerous, careful monitoring and medication may be a safer and more effective first step than immediate surgery. The case highlights that not every mass that looks like a tumor is a threat, and that in complex anatomical areas, avoiding invasive procedures when possible can lead to better results for the patient. The findings reinforce the importance of using advanced imaging and careful tissue analysis to avoid misdiagnosing a developmental anomaly as a cancer, ensuring that patients receive the right level of care without unnecessary risk.