Deciphering the clinical presentations, pathogenesis, and treatment of the idiopathic inflammatory myopathies

Abstract

The idiopathic inflammatory myopathies or myositis syndromes (the most common forms are polymyositis, dermatomyositis, and inclusion body myositis) are systemic autoimmune diseases defined by chronic muscle weakness and inflammation of unknown etiology and result in significant morbidity and mortality. Research suggests that categorizing heterogeneous myositis syndromes into mutually exclusive and stable phenotypes by using clinical and immune response features is useful for predicting clinical signs and symptoms, associated genetic and environmental risk factors, and responses to therapy and prognosis. Knowledge of myositis phenotypes should enhance clinicians' ability to recognize and manage these rare disorders.

Figure 1. Characteristic findings associated with clinical and autoantibody phenotypes in myositis

A. Heliotrope, malar rash and facial erythema in pattern of photosensitivity, as seen in this 11-year-old juvenile dermatomyositis patient with anti-p155 autoantibodies. B. Interstitial lung disease, defined by high-resolution computed tomographic (CT) scanning, is seen frequently in patients with polymyositis, as well as with the anti-synthetase autoantibody phenotype. More recently, rapidly progressive interstitial lung disease has been associated with the CADM-140 autoantibody. The chest CT scan depicted here is from a 55 year old female patient with anti-Jo-1 autoantibodies and interstitial lung disease. C. Dystrophic calcification, as present around the elbow and forearm here in this 10.5-year-old girl with juvenile dermatomyositis and anti-MJ autoantibodies, is seen in up to 25% of juvenile-onset dermatomyositis and less frequently in adult-onset disease. Calcinosis is present in > 60% of patients with the anti-MJ autoantibody phenotype. D. Lipodystrophy, loss of subcutaneous fat with frequently associated insulin resistance, diabetes and hypertriglyceridemia, are associated with juvenile-onset dermatomyositis. Generalized lipodystrophy, a widespread loss of fat from the trunk and extremities, has been associated with anti-p155 autoantibodies. A loss of fat from the arm is seen in this 20-year-old woman with juvenile onset dermatomyositis since age 8 years, who has anti-p155 autoantibodies and lipodystrophy.

Figure 1. Characteristic findings associated with clinical and autoantibody phenotypes in myositis

A. Heliotrope, malar rash and facial erythema in pattern of photosensitivity, as seen in this 11-year-old juvenile dermatomyositis patient with anti-p155 autoantibodies. B. Interstitial lung disease, defined by high-resolution computed tomographic (CT) scanning, is seen frequently in patients with polymyositis, as well as with the anti-synthetase autoantibody phenotype. More recently, rapidly progressive interstitial lung disease has been associated with the CADM-140 autoantibody. The chest CT scan depicted here is from a 55 year old female patient with anti-Jo-1 autoantibodies and interstitial lung disease. C. Dystrophic calcification, as present around the elbow and forearm here in this 10.5-year-old girl with juvenile dermatomyositis and anti-MJ autoantibodies, is seen in up to 25% of juvenile-onset dermatomyositis and less frequently in adult-onset disease. Calcinosis is present in > 60% of patients with the anti-MJ autoantibody phenotype. D. Lipodystrophy, loss of subcutaneous fat with frequently associated insulin resistance, diabetes and hypertriglyceridemia, are associated with juvenile-onset dermatomyositis. Generalized lipodystrophy, a widespread loss of fat from the trunk and extremities, has been associated with anti-p155 autoantibodies. A loss of fat from the arm is seen in this 20-year-old woman with juvenile onset dermatomyositis since age 8 years, who has anti-p155 autoantibodies and lipodystrophy.

Figure 1. Characteristic findings associated with clinical and autoantibody phenotypes in myositis

A. Heliotrope, malar rash and facial erythema in pattern of photosensitivity, as seen in this 11-year-old juvenile dermatomyositis patient with anti-p155 autoantibodies. B. Interstitial lung disease, defined by high-resolution computed tomographic (CT) scanning, is seen frequently in patients with polymyositis, as well as with the anti-synthetase autoantibody phenotype. More recently, rapidly progressive interstitial lung disease has been associated with the CADM-140 autoantibody. The chest CT scan depicted here is from a 55 year old female patient with anti-Jo-1 autoantibodies and interstitial lung disease. C. Dystrophic calcification, as present around the elbow and forearm here in this 10.5-year-old girl with juvenile dermatomyositis and anti-MJ autoantibodies, is seen in up to 25% of juvenile-onset dermatomyositis and less frequently in adult-onset disease. Calcinosis is present in > 60% of patients with the anti-MJ autoantibody phenotype. D. Lipodystrophy, loss of subcutaneous fat with frequently associated insulin resistance, diabetes and hypertriglyceridemia, are associated with juvenile-onset dermatomyositis. Generalized lipodystrophy, a widespread loss of fat from the trunk and extremities, has been associated with anti-p155 autoantibodies. A loss of fat from the arm is seen in this 20-year-old woman with juvenile onset dermatomyositis since age 8 years, who has anti-p155 autoantibodies and lipodystrophy.

Figure 1. Characteristic findings associated with clinical and autoantibody phenotypes in myositis

A. Heliotrope, malar rash and facial erythema in pattern of photosensitivity, as seen in this 11-year-old juvenile dermatomyositis patient with anti-p155 autoantibodies. B. Interstitial lung disease, defined by high-resolution computed tomographic (CT) scanning, is seen frequently in patients with polymyositis, as well as with the anti-synthetase autoantibody phenotype. More recently, rapidly progressive interstitial lung disease has been associated with the CADM-140 autoantibody. The chest CT scan depicted here is from a 55 year old female patient with anti-Jo-1 autoantibodies and interstitial lung disease. C. Dystrophic calcification, as present around the elbow and forearm here in this 10.5-year-old girl with juvenile dermatomyositis and anti-MJ autoantibodies, is seen in up to 25% of juvenile-onset dermatomyositis and less frequently in adult-onset disease. Calcinosis is present in > 60% of patients with the anti-MJ autoantibody phenotype. D. Lipodystrophy, loss of subcutaneous fat with frequently associated insulin resistance, diabetes and hypertriglyceridemia, are associated with juvenile-onset dermatomyositis. Generalized lipodystrophy, a widespread loss of fat from the trunk and extremities, has been associated with anti-p155 autoantibodies. A loss of fat from the arm is seen in this 20-year-old woman with juvenile onset dermatomyositis since age 8 years, who has anti-p155 autoantibodies and lipodystrophy.