American Board of Internal Medicine (ABIM) Certification Practice Exam

What does a c-ANCA test commonly indicate?

1. Microscopic polyangiitis

2. Ulcerative Colitis

3. Granulomatosis with polyangiitis

4. Primary Sclerosing Cholangitis

The correct answer is: Granulomatosis with polyangiitis

A c-ANCA test, or cytoplasmic anti-neutrophil cytoplasmic antibodies test, is primarily associated with granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis. This autoimmune condition is characterized by the inflammation of blood vessels, leading to damage in organs such as the lungs, kidneys, and sinuses. The presence of c-ANCA, particularly the anti-PR3 (proteinase 3) antibodies, tends to be a hallmark finding in patients with GPA. This connection makes the c-ANCA test a useful diagnostic tool in identifying this particular condition. The other options you provided do not typically correlate with c-ANCA results. Microscopic polyangiitis, while also an ANCA-associated vasculitis, is more commonly associated with p-ANCA (perinuclear ANCA) and myeloperoxidase (MPO) antibodies. Ulcerative colitis and primary sclerosing cholangitis are both related to inflammatory bowel disease but do not have a direct link to c-ANCA antibodies. Hence, granulomatosis with polyangiitis is the condition most closely associated with a positive c-ANCA test.