Recurrent Blood Eosinophilia in Ulcerative Colitis Is Associated with Severe Disease and Primary Sclerosing Cholangitis

Eosinophils are implicated in the pathogenesis of inflammatory bowel disease (IBD). A subset of IBD patients develops blood eosinophilia, and the clinical profile of these patients is undefined. We sought to characterize IBD patients with and without eosinophilia. We studied a prospective registry of 1,176 IBD patients followed in a tertiary referral center. Patients who developed eosinophilia at any time were identified by electronic medical record query. We performed a chart review case-control study comparing patients with recurrent eosinophilia versus randomly selected disease-matched patients with no history of eosinophilia. Histological analysis was performed on selected cases and controls. Eosinophilia at any time was more prevalent in ulcerative colitis (UC) patients than Crohn's disease patients (22.2 versus 12.7 %), as was recurrent eosinophilia (3.4 versus 0.7 %). UC patients with recurrent eosinophilia were predominantly male compared with the control UC population (81.3 versus 46.9 %) and had higher rates of colectomy for either medically refractory disease or dysplasia/cancer than control UC patients (56.3 versus 15.6 %). Primary sclerosing cholangitis (PSC) occurred in 37.5 % of UC patients with recurrent eosinophilia compared with only 3.1 % in the UC controls. Histological analysis of random diagnostic samples from UC patients with recurrent eosinophilia demonstrated a normal eosinophil pattern as seen in the control UC population. Eosinophilia-associated UC is a subgroup of IBD associated with severe colitis and PSC. Further studies are warranted to characterize molecular mechanisms underlying eosinophilia-associated UC and to determine optimal approaches for therapy.