ANCA

There are two main types of anti-neutrophil cytoplasmic antibodies (ANCA) - cytoplasmic (cANCA) and perinuclear (pANCA)

For the exam, remember:

• cANCA - granulomatosis with polyangiitis (Wegener's granulomatosis)
• pANCA - Churg-Strauss syndrome + others (see below)

cANCA

• most common target serine proteinase 3 (PR3)
• some correlation between cANCA levels and disease activity
• granulomatosis with polyangiitis, positive in > 90%
• microscopic polyangiitis, positive in 40%

pANCA

• most common target is myeloperoxidase (MPO)
• cannot use level of pANCA to monitor disease activity
• associated with immune crescentic glomerulonephritis (positive in c. 80% of patients)
• microscopic polyangiitis, positive in 50-75%
• Churg-Strauss syndrome, positive in 60%
• primary sclerosing cholangitis, positive in 60-80%
• granulomatosis with polyangiitis, positive in 25%

Other causes of positive ANCA (usually pANCA)

• inflammatory bowel disease (UC > Crohn's)
• connective tissue disorders: RA, SLE, Sjogren's
• autoimmune hepatitis