Granulomatosis with polyangiitis
Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis (WG), is a long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels (vasculitis). It is a form of vasculitis that affects small- and medium-size vessels in many organs but most commonly affects the upper respiratory tract, lungs and kidneys. The signs and symptoms of GPA are highly varied and reflect which organs are supplied by the affected blood vessels. Typical signs and symptoms include nosebleeds, stuffy nose and crustiness of nasal secretions, and inflammation of the uveal layer of the eye. Damage to the heart, lungs and kidneys can be fatal.
Initial signs are highly variable, and diagnosis can be severely delayed due to the nonspecific nature of the symptoms. In general, irritation and inflammation of the nose is the first sign in most people. Involvement of the upper respiratory tract, such as the nose and sinuses, is seen in nearly all people with GPA. Typical signs and symptoms of nose or sinus involvement include crusting around the nose, stuffiness, nosebleeds, runny nose, and saddle-nose deformity due to a hole in the septum of the nose. Inflammation of the outer layers of the eye (scleritis) and conjunctivitis are the most common signs of GPA in the eye; involvement of the eyes is common and occurs in slightly more than half of people with the disease.
Classic microscopic features of GPA include inflammation of blood vessels associated with poorly formed granulomas, necrosis, and many giant cells. Bacterial colonization with Staphylococcus aureus has been hypothesized as an initiating factor of the autoimmunity seen in people with GPA. Several genes involved in the immune system including PTPN22, CTLA4, and human leukocyte antigen genes may influence the risk of developing GPA.
Granulomatosis with polyangiitis is usually suspected only when a person has had unexplained symptoms for a long period of time. Determination of anti-neutrophil cytoplasmic antibodies (ANCAs) can aid in the diagnosis, but positivity is not conclusive and negative ANCAs are not sufficient to reject the diagnosis. More than 90% of people who have GPA test positive for ANCA. Cytoplasmic-staining ANCAs that react with the enzyme proteinase 3 (cANCA) in neutrophils (a type of white blood cell) are associated with GPA.
Granulomatosis with polyangiitis is part of a larger group of vasculitic syndromes called systemic vasculitides or necrotizing vasculopathies, all of which feature an autoimmune attack by an abnormal type of circulating antibody termed ANCAs (antineutrophil cytoplasmic antibodies) against small and medium-size blood vessels. Apart from GPA, this category includes eosinophilic granulomatosis with polyangiitis (EGPA) and microscopic polyangiitis. Although GPA affects small- and medium-size vessels, it is formally classified as one of the small vessel vasculitides in the Chapel Hill system.
The standard treatment for severe GPA is to induce remission with immunosuppressants such as rituximab or cyclophosphamide in combination with high-dose corticosteroids. Plasmapheresis is sometimes recommended for very severe manifestations of GPA, such as diffuse alveolar hemorrhage and rapidly progressive glomerulonephritis (as seen in pulmonary-renal syndrome). The use of plasmapheresis in those with GPA and acute kidney failure (renal vasculitis) might reduce progression to end-stage kidney disease at three months.
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