Coexistence of granulomatosis with polyangiitis (GPA) and Crohn's disease or multiorgan manifestation of the same disease?

Granulomatosis with polyangiitis (GPA) is a systemic necrotizing vasculitis of unknown aetiology, often related to the antineutrophil cytoplasmic antibody (ANCA). GPA was previously named Wegener's granulomatosis (WG). The disease frequently has multisystemic presentation, targeting mainly the respiratory tract and kidneys, but gastrointestinal involvement is uncommon. Crohn's disease (CD) is an inflammatory bowel disease (IBD) with many extraintestinal manifestations. Clinically, symptoms of WG and CD can mimic each other. In this paper a case of GPA manifested initially by severe multiorgan damage including colitis, regarded to be coexistent CD, is presented. The case illustrates the difficulties in establishing the diagnosis when symptoms of the diseases mimic each other.