consistent with cerebral vasculitis in some cases. Kidney The involvement of the kidney can be caused by primary renal parenchymal lesions, or an underlying vasculitis, or another associated autoimmune disease. Actual kidney involvement is quite rare, elevated creatinine levels are reported in approximately 10% of people with RP, and abnormalities in urinalysis in 26%. Involvement of the kidney often indicates a worse prognosis, with a 10-year survival rate of 30%. The most common histopathologic finding is mild mesangial proliferation, that is followed by focal and segmental necrotizing glomerulonephritis with crescents. Other abnormalities that are found include glomerulosclerosis, IgA nephropathy and interstitial nephritis. Immunofluorescence studies most often reveal faint deposits of C3, IgG or IgM in the primarily mesangium. Constitutional symptoms These symptoms could consist of asthenia, fever, anorexia, and weight loss. They mostly occur during a severe disease flare. Others Skin and mucous membranes: 20 to 30% of people with relapsing polychondritis have skin involvement, including aphthous ulcers, genital ulcers, and a number of non-specific skin rashes including erythema nodosum, livedo reticularis, hives, and erythema multiforme. Cardiovascular system: Relapsing polychrondritis may cause inflammation of the aorta. It can also cause leaky heart valves (aortic valve regurgitation in 4 to 10%, mitral valve regurgitation in 2%). Causes Relapsing polychondritis is an autoimmune disease in which the body's immune system begins to attack and destroy the cartilage tissues in the body. It has been postulated that both cell-mediated immunity and humoral immunity are responsible. Reasons for disease onset are not known, but there is no evidence of a genetic predisposition to developing relapsing polychondritis. However, there are cases where multiple members of the same family have been diagnosed with this illness. Studies indicate that some genetic contribution to susceptibility is likely. Diagnosis There is no specific test for relapsing polychondritis. Some people may exhibit abnormal lab results while others may have completely normal labs even during active flares. Diagnostic criteria There are several clinical criteria used to diagnose this disease. McAdam et al. introduced the clinical criteria for RP in 1976. These clinical criteria have later been expanded by Damiani et al. in 1979 and finally Michet et al. modified them in 1986. See the following table for these diagnostic clinical criteria and the number of conditions required for an official diagnosis. Laboratory findings Patients presenting with acute episodes often have high levels of inflammatory markers such as erythrocyte sedimentation rate or