A case of well-differentiated papillary mesothelial tumor concomitant with primary gastric cancer: case report and literature review.

BACKGROUND: Well-differentiated papillary mesothelial tumor (WDPMT) is a rare neoplasm characterized by low malignant potential. Due to the absence of distinct clinical symptoms, WDPMT is frequently detected incidentally during surgical procedures. CASE DESCRIPTION: This report describes a patient diagnosed with primary gastric cancer (GC) and concomitant WDPMT. The lesion was identified during laparoscopic radical gastrectomy and subsequently confirmed via histopathological and immunohistochemical analysis. No recurrence or disease progression was observed during a two-year postoperative follow-up period. CONCLUSION: WDPMT remains a relatively rare disease. In addition to histopathological evaluation, immunohistochemistry and, where available, molecular genetic analysis contribute to diagnostic accuracy. However, conclusive evidence from large-scale studies are currently lacking. The overall prognosis of WDPMT is favorable, with surgical excision representing the standard therapeutic approach.