What does “ANCA” stand for? What rheumatologic condition is most strongly associated with the presence of C-ANCA? List three disease associations with P-ANCA.
“ANCA” stands for anti-nuclear cytoplasmic antibodies.
On immunofluorescence, a C-ANCA is characterized by diffuse cytoplasmic staining. This usually corresponds with antibodies to the antigen PR3 (proteinase-3).
P-ANCA refers to a perinuclear immunofluorescence staining pattern and usually corresponds with antibodies to the antigen MPO (myeloperoxidase).
80-90% of patients with Wegener’s granulomatosis are C-ANCA positive. In some patients, C-ANCA titres reflect disease activity. Microscopic polyangiitis, Churg-Strauss vasculitis, renal-limited vasculitis and Goodpasture’s (anti-GBM) disease are all associated with the presence of P-ANCA. Note that P-ANCA positivity is also associated with a number of non-rheumatologic conditions, including drug-related vasculitis, connective tissue diseases, inflammatory bowel disease, and cystic fibrosis.