Our group has experience of diagnosis and treatment of difficult and rare gastrointestinal diseases, such as IgG4-related disease、Hereditary Angioedema (HAE)、Eosinophilic Gastroenteritis (EG)、Cronkhite-Canada Syndrome (CCS)、Collagenous Gastritis（CG）、Juvenile Polyposis Syndrome(JPS), etc. Case reports of those rare gastrointestinal diseases also were published on SCI-indexed journal, such as Gut(An unusual cause of oesophageal stricture; Underdiagnosed cause of gastrointestinal bleeding),Dig Liver Dis (IgG4-related disease with duodenal bulb involvement; Pemphigus Vulgaris: A rare cause of esophageal bleeding and stricture), Dig Dis Sci (Esophageal Ulcer: Behçet's Disease or Tuberculosis?), etc.