Epigastric pain of unknown origin, esophageal and gastric involvement: a Henoch-Schönlein Purpura case report - Li, Mengmeng; Huang, Chaoyuan; Xing, Hailun; Luo, Shijuan; Lin, Yiqun; Kuang, Yuxiang; Wang, Jing; Huang, Suiping; Ye, Zhenhao (Frontiers in Medicine, 2025)