Synchronous Oral Heterotopic Gastrointestinal Cyst and Oral Squamous Cell Carcinoma: First Case Report

Background. Synchronous lesions in the oral cavity are uncommon and present diagnostic challenges, particularly when a benign lesion coexists with a malignancy. Heterotopic gastrointestinal cyst of the oral cavity (HGIC), typically seen in pediatric patients, contains ectopic gastrointestinal tissue and is rarely found in adults. This report describes a case of a HGIC in an adult patient concomitant with oral squamous cell carcinoma (OSCC), which is believed to be the first report of this unique entity. Methods and results. A 62-year-old man presented with an ulcerated lesion on the right floor of the mouth. An incisional biopsy was performed, and the pathology revealed that it was an HGIC with a pathological cavity lined by tall columnar epithelial cells with basally displaced nuclei and apical microvilli (brush border), synchronous with an SCC exhibiting a proliferation of epidermoid cells with moderate cellular atypia, pleomorphism, and nuclear hyperchromatism. The patient is currently undergoing regular follow-up, with further evaluations planned to monitor local disease control and prevent potential complications. Conclusion. Early and accurate identification of coexisting lesions may be crucial for effective clinical management and a broader understanding of the pathogenesis of these conditions.