Histopathologic and Lymphocyte Subpopulations Evaluation of the Upper Gastrointestinal Tract of Crohn's Disease

Inflammatory bowel disease (IBD) comprises a series of disorders of unknown cause, such as ulcerative colitis (UC), Crohn's disease (CD) and indeterminate colitis (IC), associated with an over-the-top immune response that produces lesions of variable depth and extent in the intestine. They have a chronic course, without cure and with an unpredictable evolution. Clinical symptoms of CD are characterized by malaise, weight loss, fever, diarrhoea, abdominal pain, vomiting, sometimes palpable mass, perianal disease, among others. The disease is most frequently located in the ileocecal area, but all the entire digestive tract from the oral cavity to the rectum may be affected. The involvement of the upper gastrointestinal tract (UGT) (L4) in CD is frequently undiagnosed. From 1-7% of patients with CD refer symptoms or signs that are due to UG involvement. Chronic iron deficient anaemia, in the absence of digestive symptoms, is the only guiding sign that may alert about the diagnosis. Furthermore, retrospective cohort studies suggest that CD of the UGT is associated with a worse prognosis. The systematic study of the UGT in the initial evaluation of CD at the time of diagnosis is not generally recommended in adulthood, European Crohn's and Colitis Organisation (ECCO) guidelines recommend upper endoscopy only if there are upper digestive symptoms (vomiting, dyspepsia, etc.). In the case of gastroscopy, gastric biopsies have to be performed due to the possible presence of focal active gastritis, which is considered very specific of CD. This statement is based on a limited series of cases published in 1980. On the other hand, systematic performance of duodenal biopsies is not recommended. This fact has caused that the histopathology of duodenal CD is very unknown and the need to perform duodenal biopsies of the UGT is still a matter of debate. Macro and microscopic findings from the UGT have generally been used to differentiate between UC and CD in cases of IC. Among the m