Abdominal pain, diarrhea, weight loss, abdominal masses, intestinal obstruction, fever, arthralgia, skin erythema, eye iritis, mouth ulcers, stools coming out of the abdominal wall, bladder, and vagina …… What is this disease with such strange and varied clinical manifestations? This is the number one strange disease in gastroenterology – Crohn’s disease (CD). This disease was only systematically described by the American surgeon Crohn’s in 1932 and was officially named “Crohn’s disease” in 1973, so it can be said to be a “new disease”. Because of its late formal naming and low incidence, many clinicians at home and abroad know little about CD, which has a variety of clinical manifestations and is difficult to diagnose, insidious and difficult to investigate, and is often confused with other common gastrointestinal diseases. For surgeons, CD is like a “landmine” that can have serious consequences if it is accidentally stepped on. Therefore, it is necessary to understand CD to avoid stepping on the mines. 1, recurrent perianal abscess Xiao Li was found to have CD only after surgery for a perianal abscess. back in March 2010, Xiao Li was hospitalized and opened because of a perianal abscess, and the wound kept growing badly after he was discharged, so he had to be opened again. A few days later, he had frequent diarrhea and weighed only about 90 pounds at the time. Later, his condition was gradually brought under control and the wound became smaller, but he had abdominal pain, once or twice a day. The doctor suspected CD, so on September 4, a colonoscopy was done, and the colonoscopy revealed that there were jumping cobblestone-like irregular mucosal elevations in the intestines, with surface erosion and bleeding when touched. At this point, Xiao Li was finally diagnosed with CD. clinically, the possibility of CD should be considered when the site of recurrence is inconsistent with the original lesion site, accompanied by wasting and gastrointestinal symptoms. 2, post-appendicitis enterocutaneous fistula The initial onset of CD is usually in the gastrointestinal tract and often has similarities with other intestinal diseases, sometimes very similar to the symptoms of acute appendicitis, which can appear as pressure pain in the right lower abdomen, rebound pain, fever, elevated white blood cells and so on, while acute appendicitis is a relatively common emergency case. If CD is misdiagnosed as acute appendicitis and an appendectomy is performed, an intestinal fistula can occur after surgery. The possibility of CD should be considered clinically when the patient has wasting and gastrointestinal symptoms. 3, incontinence after hanging fistula The diagnosis of CD with perianal lesions as the first clinical manifestation may be more difficult or even easy to be ignored. If multiple perianal lesions are present at the same time, such as anal fissures, ulcerated cavities, and anal canal stenosis in non-median areas, CD should be considered clinically, and the possibility of CD combined with anal fistula should be considered in cases where the internal opening is above the dentate line, multiple external openings of the fistula, the external opening is >3 cm from the anal verge, and the fistula is wide. Once the possible presence of CD is ignored and the anal fistula is treated by cutting and hanging according to conventional therapy, it is easy to cause anal incontinence. 4, problematic storage bag CD and ulcerative colitis (UC) in the clinical presentation can be very similar, sometimes difficult to identify, so the two collectively known as inflammatory bowel disease (IBD). Once CD is misdiagnosed as UC, and after pouch surgery (IPAA) is done, serious complications such as pouch vaginal fistula are likely to occur, and eventually the pouch will have to be removed and a permanent stoma made. Conclusion There is no gold standard for the diagnosis of CD. In most clinical settings, other diseases are ruled out first, and then a diagnosis can be made only after a comprehensive analysis of stool culture, endoscopy, tissue biopsy and other ancillary tests. Due to historical reasons and the diverse clinical manifestations of CD, it is sometimes difficult to avoid clinical misdiagnosis and missed diagnosis. However, it is important to raise awareness of CD to avoid stepping on mines. Clues suggesting CD: wasting, chronic abdominal pain, diarrhea, atypical location of the internal and external openings of the fistula, and anal fissures in non-midline sites.