Endoscopic and Clinicopathological Analysis of Non-Ampullary Duodenal Epithelial Tumors with Gastrointestinal Mixed Phenotype Based on Predominant Phenotype

Aims Non-ampullary duodenal epithelial tumors (NADETs) are known to exhibit specific endoscopic and clinicopathological characteristics depending on their mucin phenotypes. However, NADETs with a gastrointestinal mixed phenotypes (GMP) have not been thoroughly analyzed. This study aimed to elucidate the endoscopic and clinicopathological characteristics of NADETs with GMP by classifying NADETs into four groups: gastric predominant type (GP), gastric predominant mixed phenotype (GPP), intestinal predominant mixed phenotype (IPP), and intestinal predominant type (IP), and conducting a comparative analysis.

Methods A total of 218 patients with 229 NADETs lesions that underwent endoscopic or surgical resection at our institution from February 2010 to December 2023 were analyzed. Based on immunohistochemistory, NADETs were classified into four groups: GP, GPP, IPP, and IP. Lesions with predominant positivity for MUC5AC or MUC6 were classified as GPP, and those with predominant positivity for MUC2 or CD10 were classified as IPP in the GMP.

Results Among the 229 NADETs, GP/GPP/IPP/IP were 20/22/69/118 lesions. Lesion location (bulb/descending/horizontal) was GP=13/7/0, GPP=12/8/2, IPP=13/52/4, and IP=16/94/8. Mean tumor sizes for GP/GPP/IPP/IP were 14.7/18.5/10.9/10.3 mm, and the rate of cancer was 50/68.1/11.9/2.5%, respectively. In the comparisons between GP vs. GPP/IP vs. IPP, IPP showed a significantly higher rate of cancer than IP (p<0.01), WOS-negativity was significantly more frequently observed in GP than in GPP (p<0.01), and no significant differences were observed in other factors. Thus, GP and IPP were almost identical to the results of their predominant pure phenotypes. Moreover, “GP+GPP” was significantly more frequently observed in bulb compared to “IPP+IP” (p<0.01), “GP+GPP” were significantly larger (p<0.01), and showed a higher rate of cancer than “IPP+IP” (p<0.01). In white light imaging, the coloration was more reddish in “GP+GPP” than in “IPP+IP”, lobulated/granular appearance and protruded type were significantly more frequently observed in “GP+GPP” than in “IPP+IP” (p<0.01). In magnifying endoscopy with narrow-band imaging, irregular microvascular/microsurface pattern, WOS-negativity, oval-shaped marginal epithelium, dense patterns, and dilatation of intervening part were significantly more frequently observed in “GP+GPP” than in “IPP+IP” (p<0.01).

Conclusions NADETs with a GMP demonstrated the endoscopic and clinicopathological characteristics of their predominant phenotype. With respect to malignant potential, the cancer ratio was higher in the order of GPP>GP>IPP>IP. Although there was no significant difference between GP and GPP, it was suggested that the GMP may have a higher malignant potential compared to its predominant pure phenotype.

Publication History

Article published online:
27 March 2025