Aims

Heterotopic bone formation is an uncommon finding in the gastrointestinal tract. Mesenchymal metaplasia, particularly osseous metaplasia (OM), is occasionally reported in malignant tumors but remains rare in benign polyps. OM is more frequently described in colonic polyps, whereas its occurrence in gastric polyps is exceptional, with only about ten cases reported in the literature. It has also been described in juvenile polyps, either sporadically or in association with Peutz–Jeghers syndrome.The exact pathogenesis is not well established, although most hypotheses suggest an inflammation-driven mechanism leading to osteogenic stimulation.While heterotopic ossification has been documented in various benign and malignant intestinal lesions, its development in the duodenum is exceedingly rare.We report a case of OM occurring in a duodenal nodule in a 31-year-old woman.

Methods

A 31-year-old female patient with no significant medical history presented with chronic epigastric pain. Laboratory investigations were within normal limits (Hb 13.9 g/dL).An esophagogastroduodenoscopy (EGD) was performed.

Results

EGD revealed a sliding hiatal hernia, congestive antral gastropathy, and a millimetric duodenal nodule.Histopathologic examination showed inflammatory and edematous–congestive changes in the duodenal mucosa with clear evidence of osseous metaplasia. No Helicobacter pylori infection, dysplasia, or malignancy was identified.A follow-up EGD performed one month later was normal.Although OM is considered to have limited clinical significance, its recognition is important to avoid misdiagnosis. No endoscopic surveillance is recommended once the diagnosis is confirmed.

Conclusions

Osseous metaplasia is a rare entity in the upper gastrointestinal tract and exceptionally uncommon in the duodenum. Increased awareness among endoscopists and histopathologists is essential for accurate identification and appropriate diagnosis, preventing unnecessary interventions or follow-up.