Any of a group of diseases involving connective tissue; formerly termed collagen vascular disease. These diseases are clinically and pathologically discrete from each other but have overlapping features. The group includes lupus erythematosus, systemic vasculitis, polymyolitis, scleroderma (and systemic sclerosis), and Sjögren's syndrome. Each of the diseases can involve multiple organ systems and is often coupled with various immunologic abnormalities. See also Connective tissue.
The set of diseases known as lupus erythematosus includes limited, primarily cutaneous disorders (discoid lupus and sub-acute cutaneous lupus) and a diffuse systemic illness (systemic lupus erythematosus), all of which are of unknown cause. Also, a lupuslike reaction known as drug-induced lupus can be caused by certain therapeutic agents.
Systemic vasculitis comprises a series of different clinical illnesses that are all characterized by intense inflammation in the walls of blood vessels, especially arteries (that is, arteritis). These illnesses differ clinically, pathologically, and with respect to therapeutic responsiveness and outcome. Even the age and sex of the typical affected person varies from one to another. The clinical pattern of illness varies with the sites of blood vessel involvement and the character of vascular injury. Tissue death in the vessel wall can lead to narrowing, or even blockage, of the vessel or weakening of the wall with formation of an aneurysm. Impaired circulation and altered blood flow result. Symptoms, therefore, can arise not only from the tissue inflammation itself but also from the lack of adequate blood supply. See also Aneurysm; Circulation disorders.
Polymyositis involves intense inflammation in skeletal muscle that, if untreated, can lead to destruction of muscle fibers. When typical skin lesions are present, the term dermatomyosi-tis is applied. The cause of polymyositis, or dermatomyositis, is not known in most cases. These conditions can occur alone or in association with other connective tissue disorders (that is, systemic lupus, scleroderma, and Sjögren's syndrome). In older persons, they sometimes accompany malignant tumors. If diagnosed early, before loss of muscle fibers and replacement by fibrous scarring is extensive, myositis is reversible; recovery with minimal residual loss of strength is to be expected in almost all patients.
The term scleroderma means “hard skin,” designating a disorder in which increased deposition of collagen fibers in the deeper dermis leads to thickened, leathery, bound-down skin. When organ involvement is associated with such skin changes, the term systemic sclerosis is used. Raynaud's phenomenon, a hyperreactivity to cold exposure with blanching and discoloration of the fingers and toes, is the common initial manifestation and may precede sclerodermatous skin changes by decades. Systemically, the gastrointestinal tract is most commonly involved. Difficulty in swallowing and mid-chest discomfort result from loss of peristalsis in the esophagus. Diarrhea, inability to absorb nutrients, abdominal pain, and distention can occur with bowel involvement and lead to weight loss and wasting. Scarring of the lungs and decreased pulmonary function occur frequently. The most serious lesions are those of the heart and kidney, which may result from vascular abnormalities related to Raynaud's phenomenon. Joint inflammation is mild and uncommon; but advanced skin changes, especially in the hands, may restrict joint mobility.
Sjögren's syndrome is characterized primarily by dryness of the membranes due to excretory gland failure, especially dry-ness of the eyes (xerophthalmia) and mouth (xerostomia) from loss of tears and saliva, respectively. This sicca (dryness) syndrome reflects the infiltration of lacrimal and salivary glands by immunologically competent cells (lymphocytes). Sjögren's syndrome may be primary or secondary; that is, superimposed on another disorder like rheumatoid arthritis or systemic lupus. See also Immunology; Inflammation.
