Background and aims: 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.
Methods: 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.
Results: 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.
Conclusions: 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.