Dermatomyositis Health Dictionary

BURSITIS, TENDINITIS and non-speci?c back pain (see BACKACHE).

Osteoarthritis (OA) rarely starts before 40, but by the age of 80 affects 80 per cent of the population. There are structural and functional changes in the articular cartilage, as well as changes in the collagenous matrix of tendons and ligaments. OA is not purely ‘wear and tear’; various sub-groups have a genetic component. Early OA may be precipitated by localised alteration in anatomy, such as a fracture or infection of a joint. Reactive new bone growth typically occurs, causing sclerosis (hardening) beneath the joint, and osteophytes – outgrowths of bone – are characteristic at the margins of the joint. The most common sites are the ?rst metatarsal (great toe), spinal facet joints, the knee, the base of the thumb and the terminal ?nger joints (Heberden’s nodes).

OA has a slow but variable course, with periods of pain and low-grade in?ammation. Acute in?ammation, common in the knee, may result from release of pyrophosphate crystals, causing pseudo-gout.

Urate gout results from crystallisation of URIC ACID in joints, against a background of hyperuricaemia. This high concentration of uric acid in the blood may result from genetic and environmental factors, such as excess dietary purines, alcohol or diuretic drugs.

In?ammatory arthritis is less common than OA, but potentially much more serious. Several types exist, including: SPONDYLARTHRITIS This affects younger men, chie?y involving spinal and leg joints. This may lead to in?ammation and eventual ossi?cation of the enthesis – that is, where the ligaments and tendons are inserted into the bone around joints. This may be associated with disorders in other parts of the body: skin in?ammation (PSORIASIS), bowel and genito-urinary in?ammation, sometimes resulting in infection of the organs (such as dysentery). The syndromes most clearly delineated are ankylosing spondylitis (see SPINE AND SPINAL CORD, DISEASES AND INJURIES OF), psoriatic or colitic spondylitis, and REITER’S SYNDROME. The diagnosis is made clinically and radiologically; no association has been found with autoantibodies (see AUTOANTIBODY). A particularly clear gene locus, HLA B27, has been identi?ed in ankylosing spondylitis. Psoriasis can be associated with a characteristic peripheral arthritis.

Systemic autoimmune rheumatic diseases (see AUTOIMMUNE DISORDERS). RHEUMATOID ARTHRITIS (RA) – see also main entry. The most common of these diseases. Acute in?ammation causes lymphoid synovitis, leading to erosion of the cartilage, associated joints and soft tissues. Fibrosis follows, causing deformity. Autoantibodies are common, particularly Rheumatoid Factor. A common complication of RA is Sjögren’s syndrome, when in?ammation of the mucosal glands may result in a dry mouth and eyes. SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) and various overlap syndromes occur, such as systemic sclerosis and dermatomyositis. Autoantibodies against nuclear proteins such as DNA lead to deposits of immune complexes and VASCULITIS in various tissues, such as kidney, brain, skin and lungs. This may lead to various symptoms, and sometimes even to organ failure.

Infective arthritis includes: SEPTIC ARTHRITIS An uncommon but potentially fatal disease if not diagnosed and treated early with approriate antibiotics. Common causes are TUBERCLE bacilli and staphylococci (see STAPHYLOCOCCUS). Particularly at risk are the elderly and the immunologically vulnerable, such as those under treatment for cancer, or on CORTICOSTEROIDS or IMMUNOSUPPRESSANT drugs. RHEUMATIC FEVER Now rare in western countries. Resulting from an immunological reaction to a streptococcal infection, it is characterised by migratory arthritis, rash and cardiac involvement.

Other infections which may be associated with arthritis include rubella (German measles), parvovirus and LYME DISEASE.

Treatment Septic arthritis is the only type that can be cured using antibiotics, while the principles of treatment for the others are similar: to reduce risk factors (such as hyperuricaemia); to suppress in?ammation; to improve function with physiotherapy; and, in the event of joint failure, to perform surgical arthroplasty. NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS) include aspirin, paracetamol and many recently developed ones, such as the proprionic acid derivatives IBUPROFEN and naproxen, along with other drugs that have similar properties such as PIROXICAM. They all carry a risk of toxicity, such as renal dysfunction, or gastrointestinal irritation with haemorrhage. Stronger suppression of in?ammation requires corticosteroids and CYTOTOXIC drugs such as azathioprine or cyclophosphamide. Recent research promises more speci?c and less toxic anti-in?ammatory drugs, such as the monoclonal antibodies like in?iximab. An important treatment for some osteoarthritic joints is surgical replacement of the joints.... joints, diseases of

Telangiectasia is not a cause for concern, but the veins can be removed in some cases by electrodesiccation (electrical destruction of the upper layers of the skin). (See also spider naevus.)... telangiectasia

Others appear under their appropriate alphabetical headings: ACNE; ALBINISM; ALOPECIA; ALOPECIA AREATA; APHTHOUS ULCER; BASAL CELL CARCINOMA; BOILS (FURUNCULOSIS); BOWEN’S DISEASE; CALLOSITIES; CANDIDA; CHEILOSIS; CHEIRAPOMPHOLYX; DANDRUFF; DERMATOFIBROMA; DERMATOMYOSITIS; DERMATOPHYTES; DERMOGRAPHISM; ECTHYMA; ERYSIPELAS; ERYTHEMA; ERYTHRASMA; ERYTHRODERMA; ESCHAR; EXANTHEM; FUNGAL AND YEAST INFECTIONS; HAND, FOOT AND MOUTH DISEASE; HERPES GENITALIS; HERPES SIMPLEX; HERPES ZOSTER; IMPETIGO; INTERTRIGO; KELOID; KERATOSIS; LARVA MIGRANS; LICHEN; LUPUS; MADURA FOOT; MELANOMA; MILIARIA; MOLLUSCUM CONTAGIOSUM; MOLE; MYCOSIS FUNGOIDES; NAEVUS; ORF; PEDICULOSIS; PEMPHIGUS; PHOTOCHEMOTHERAPY; PHOTODERMATOSES; PITYRIASIS; PORPHYRIAS; PRURITUS; PSORIASIS; RINGWORM; ROSACEA; SARCOIDOSIS; SCABIES; SCLERODERMA; URTICARIA; VITILIGO; WARTS; XANTHOMATA.

Skin cancer Primary cancer is common and chronic exposure to ultraviolet light is the most important cause. BASAL CELL CARCINOMA is the most common form; squamous cell carcinoma is less common and presents as a growing, usually painless nodule which may ulcerate. Squamous cancer may spread to regional lymph glands and metastasise, unlike basal cell cancer. Occupational exposure to chemical carcinogens may cause squamous carcinoma – for example, cancer from pitch warts or the scrotal carcinoma of chimney sweeps exposed to coal dust in earlier centuries. Squamous carcinoma of the lip is associated with clay-pipe smoking.

Cancer may arise from the population of melanocytes of the skin (see MELANOCYTE; MELANOMA).

Apart from these three most frequent forms of skin cancer, various forms of cancer can arise from cells of the dermis, of which LYMPHOMA is the most important (see also MYCOSIS FUNGOIDES).

Lastly, secondary deposits from internal cancer, particularly from the breast, may metastasise to the skin.

Dermatitis and eczema These are broadly synonymous, and the terms are frequently interchangeable. Eczema is a pattern of in?ammation with many potential causes. Dermatitis is commonly used to suggest an eczema caused by external factors; it is a common pattern of in?ammation of the skin characterised by redness and swelling, vesiculation (see VESICLE), and scaling with intense itching and often exudation (weeping). Fissuring, thickening (licheni?cation – see LICHEN) and secondary bacterial infection may follow. Dermatitis can affect any part of the body. It may be genetically detemined or due to other ‘internal’ factors, such as venous HYPERTENSION in a leg, or stress. Often it is ‘external’ in origin – due to strong irritants or chemical allergens. (See also ALLERGY; ALLERGEN.) ATOPIC DERMATITIS is genetic in origin and usually begins in infancy. It may persist for years, and ASTHMA, allergic RHINITIS and conjunctivitis (see under EYE, DISORDERS OF) – ‘hay fever’ – may be associated. Atopic children tend to have multiple allergies, especially to inhaled allergens such as house-dust mite, cat and dog dander and pollens. Allergy to foods is less common but potentially more dangerous, especially if to nuts, when it can cause acute URTICARIA or even ANAPHYLAXIS. Atopic subjects are particularly prone to persistent and multiple verrucae (see WARTS) and mollusca (see MOLLUSCUM CONTAGIOSUM) and to severe HERPES SIMPLEX infections. (See also ATOPY.)

EXFOLIATE DERMATITIS (PITYRIASIS RUBRA)

Generalised exfoliation and scaling of the skin, commonly with ERYTHEMA. Drugs may cause it, or the disorder may be linked with other skin diseases such as benign dermatoses and lupus erythematosus (see under LUPUS). SUMMER POMPHOLYX is an acute vesicular eczema of the palms and soles recurring every summer. Inhaled allergens are a frequent cause. VENOUS (STASIS) DERMATITIS begins on a lower calf, often in association with PURPURA, swelling and sometimes ulceration. Chronic venous hypertension in the leg, consequent on valvular incompetence in the deep leg veins owing to previous deep vein thrombosis (see VEINS, DISEASES OF), is the usual cause. NEURODERMATITIS A pattern of well-de?ned plaques of licheni?ed eczema particularly seen on the neck, ulnar forearms or sides of the calves in subjects under emotional stress. IRRITANT CONTACT DERMATITIS Most often seen in an industrial setting (occupational dermatitis), it is due to damage by strong chemicals such as cutting oils, cement, detergents and solvents. In almost all cases the hands are most severely affected. ALLERGIC CONTACT DERMATITIS, in contrast, can affect any part of the body depending on the cause – for example, the face (cosmetics), hands (plants, occupational allergens) or soles (rubber boots). Particularly common allergens include metals (nickel and chromate), rubber addititives, and adhesives (epoxy resins).

Treatment Avoidance of irritants and contact allergens, liberal use of EMOLLIENTS, and topical application of corticosteroid creams and ointments (see CORTICOSTEROIDS) are central.... skin, diseases of