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It is a rare disease with prevalence estimated at between 1/42,000 and 1/6,400 inhabitants and an annual incidence varying between 2 and 12 cases per million.

Both sexes are affected. The average age of onset is 45 years but forms have been described in very elderly subjects and children. In its complete form, the disease is clinically characterised by ear, nose and throat manifestations in 70 to 100% of patients (persistent nasal obstruction, sinusitis, haemorrhagic and/or crust-forming rhinitis, serous otitis media, hearing loss and/or saddle nose deformity), pulmonary involvement (nodules, infiltration and alveolar haemorrhage) and renal disease (typically extracapillary necrotizing glomerulonephritis). General signs (asthenia, fever, arthralgia, myalgia and/or weight loss) are frequent. Peripheral neuropathy (principally multineuritis) is present in 11-68% of patients and central nervous system manifestations (headaches, sensorimotor deficit, hemiplegia and epilepsy) are observed in 6-13% of cases. Cutaneous lesions (purpura, papules and ulcers) are found in 10-50% of patients. Ocular anomalies are frequent (14-60% of cases). Cardiac involvement is less common (less than 10% of patients) and is often asymptomatic.

The aetiology is unknown.

Diagnosis relies on recognition of the clinical picture and detection of antineutrophil cytoplasmic antibodies (ANCAs) in the serum, principally cANCA anti-PR3. Biopsy of the skin or tissue from the nose, lungs or kidneys should allow confirmation of the diagnosis.

Treatment of systemic forms relies on corticotherapy in association with intravenous administration of cyclophosphamide, initially every two weeks and then every three weeks until the patient is in remission. An alternative immunosuppressive agent (azathioprine or methotrexate) is then used as a maintenance therapy. Biotherapies (rituximab, anti-TNF alpha, abatacept, etc.) are currently under study with promising results.

With treatment, disease remission is achieved in 85% of cases but recurrence occurs in half of the patients during the five years following the diagnosis.