Dermamyositis Flashcards
(26 cards)
What is dermatomyositis (DM)?
A systemic autoimmune disease characterized by chronic inflammation of the skin and muscles, often associated with other systemic features.
What is the hallmark feature of dermatomyositis?
A combination of proximal muscle weakness and distinctive cutaneous findings.
What is the typical age of onset for dermatomyositis?
Bimodal distribution: in children (juvenile DM) and adults aged 40–60 years
What is the underlying cause of dermatomyositis?
Unknown, but it involves immune-mediated damage to muscle and skin, possibly triggered by environmental factors in genetically predisposed individuals
What is the primary immunopathologic mechanism in dermatomyositis?
Complement-mediated microangiopathy causing damage to capillaries in the skin and muscle.
Which autoantibodies are commonly associated with dermatomyositis?
Anti-Mi-2: Associated with classic DM and good prognosis.
Anti-Jo-1: Associated with interstitial lung disease (ILD) and mechanic’s hands.
Anti-TIF1γ and anti-NXP2: Associated with malignancy in adult DM.
What type of muscle weakness is seen in dermatomyositis?
Symmetrical proximal muscle weakness (e.g., difficulty climbing stairs, rising from a chair).
Are distal muscles typically involved in dermatomyositis?
Rarely, and usually only in severe cases.
Is muscle pain a common feature of dermatomyositis?
Muscle pain or tenderness occurs in some cases but is not a prominent feature.
What is the most specific skin finding in dermatomyositis?
Gottron’s papules: Violaceous, scaly papules over bony prominences like the knuckles, elbows, and knees.
What is the characteristic rash seen on the face in dermatomyositis?
Heliotrope rash: A violaceous discoloration around the eyelids, often with periorbital edema.
What is the “shawl sign” in dermatomyositis?
A photodistributed erythematous rash over the shoulders, upper chest, and back.
What is the “V sign”?
A photodistributed rash over the anterior chest in the shape of a “V”.
What are “mechanic’s hands”?
Hyperkeratosis, cracking, and fissuring of the skin on the fingers, often associated with anti-synthetase syndrome.
What systemic features are commonly associated with dermatomyositis?
Fatigue, weight loss, fever, Raynaud’s phenomenon, and interstitial lung disease (ILD).
What gastrointestinal complication is seen in juvenile dermatomyositis?
Calcinosis: Calcium deposits in the skin and soft tissues.
What malignancies are associated with adult dermatomyositis?
Ovarian, breast, lung, gastric, pancreatic, and colorectal cancers.
What are the diagnostic criteria for dermatomyositis?
Symmetrical proximal muscle weakness.
Elevated muscle enzymes (CK, LDH, aldolase, AST/ALT).
Myopathic changes on electromyography (EMG).
Characteristic skin findings.
Muscle biopsy showing perifascicular atrophy and inflammation.
What imaging modality is useful in diagnosing muscle involvement in dermatomyositis?
MRI, which can detect muscle edema and inflammation.
Which skin biopsy finding is characteristic of dermatomyositis?
Interface dermatitis with a lymphocytic infiltrate and basal layer vacuolization.
What is the first-line treatment for dermatomyositis?
High-dose corticosteroids (e.g., prednisone) to suppress inflammation.
What steroid-sparing agents are commonly used in dermatomyositis?
Methotrexate and azathioprine.
Which medication is used in refractory cases of dermatomyositis?
Intravenous immunoglobulin (IVIG), rituximab, or mycophenolate mofetil.
How is skin disease in dermatomyositis managed?
Sun protection and avoidance of UV exposure.
Topical corticosteroids or calcineurin inhibitors (e.g., tacrolimus).
Antimalarials (e.g., hydroxychloroquine) for resistant cutaneous disease.
