Polymyositis
Definition
Disease of unknown aetiology produces inflammation and muscle degeneration
Epidemiology
Begins in childhood
More common in females
Symptoms
Proximal muscle weakness
- muscles tender & swollen
- brawny & indurated
Arthralgias
- frequently hands, wrists, and knees
Starts with systemic symptoms
- skin rash, fever, malaise
Investigations
Creatine Phosphokinase elevated
Muscle biopsy
- inflammatory infiltration & necrosis
Xray
May see subcutaneous calcification
- classically seen in the proximal large muscles
- occasionally, the calcification assumes a sheet-like pattern along fascial or muscle planes
- is considered nearly pathognomonic for dermatomyositis
Management
Acute
- symptomatic
- corticosteroids
- immunosuppressive medication for resistant cases
Chronic
- physiotherapy
- orthotics
- surgical release of contractures
Dermatomyositis
Epidemiology
Can occur at any age
- peak in childhood
- peak in late adulthood
- more common in females
Clinical Features
Similar to polymyositis
Rash more prominent
- photosensitive
- malar butterfly distribution
Management
As for polymyositis
Complications
Associated with neoplasm in 10-20%
Polymyalgia Rheumatica
Epidemiology
Middle aged women
Symptoms
Tender pectoral & pelvic muscles
Risk Temporal Arteritis
Investigations
ESR high
Management
Rapid response low dose steroids
Postinfectious Arthritis
Aetiology
Meningococcal arthritis
- most commonly
Streptococcal arthritis
- occasionally
Represents Arthus reaction
- interaction of newly produced circulating antibodies & bacterial antigens in synovium
- interaction produces immune complexes & inflammatory response
Sarcoidosis
Aetiology
Unknown cause
- characterised by non-caseating granulomata
- can affect any organ at any age
Clinically
Most commonly affects the chest in young adults
- bilateral hilar lympadenopathy
- cough, fever, arthralgia, malaise, erythema nodosum
Also affects
- skin - rash
- eyes - uveitis
- heart
- CNS - hearing, balance
- renal
- MSK system
Two Musculoskeletal Forms
Symmetrical small joint polyarthropathy without bony involvement
- erythema nodosum
- hilar lymphadenopathy
Chronic granulomatosis bony involvement
- polyarthritis
- tenosynovitis
- punched out lucent bony "cyst"
- especially hand & feet
Scleroderma
Definition
Autoimmune Disease
CREST Syndrome
1. Calcinosis
2. Raynaud's
3. Esophageal Strictures
4. Sclerodactyly
5. Telangiectasia
Clinical Features
Typical patient middle aged female
- cushingoid facies
Hands
Stiff shiny digits with loss of creases and flexion contractures
- autoamputation / acro-osteolysis - osteolysis of the tufts of DP (80%)
- punctate calcification of the terminal phalanx
- telangiectasia
- calcium nodules
Important to consider vascular supply to hand prior to OT
Extraskeletal
Lung fibrosis
CRF
Calcification (subcutaneous, extra-articular, occasionally intra-articular
Xray
Calcification in ST of digits
Osteopenia
Joint erosion
Investigations
DDx RA
- up to 40% scleroderma have positive RF