[Non SLE connective tissue diseases: general aspects and kidney]

Connective tissue diseases represent a group of heterogeneous disorders that share certain common features, including inflammation of the skin, joints and other structures rich in connective tissue, as well as altered immunoregulation patterns, including autoantibody production and cell-mediated immunity abnormalities. While certain distinct clinical entities can be defined, manifestations can vary considerably from patient to patient, and the overlap of clinical features between and among specific diseases is common. Genetic, environmental and sex hormonal factors are likely to be of pathogenic importance. Among these diseases, systemic lupus erythematosus is the most frequent, followed by systemic sclerosis or scleroderma (SSc), Sjogren's disease, polymyositis and dermatomyositis and mixed connective tissue disease. Systemic sclerosis involves multiple organs in a process consisting of disseminated sclerosis affecting all compartments. Prominent vascular lesions typify the renal lesions. Scleroderma crisis is a major complication of SSc, characterized by severe hypertension, rapidly progressive renal failure, thrombotic microangiopathy with hemolitic anemia and low platelet count: the prompt use of angiotensin-converting enzyme (ACE) inhibitors significantly increased the 1-yr survival rate from 15 to 76%. Sjogren's syndrome is an immunologic disorder characterized by progressive lymphocytic destruction of the exocrine gland, frequently resulting in symptomatic eye and mouth dryness. The interstitial lesions constitute the principal renal manifestations: interstitial infiltrates and small lymphocytes, which can be homogenous and massive. In polymyositis and dermatomyositis renal involvement is rare.