Skin Deep: DM Manifestations
This classic dermatomyositis skin finding consists of raised, violaceous papules located over the knuckles.
Gottron's papules
This is the most commonly detected myositis-specific autoantibody, targeting histidyl-tRNA synthetase, and is central to anti-synthetase syndrome.
Anti-Jo-1
In a patient with classic dermatomyositis features, this serum enzyme is characteristically elevated and reflects muscle damage.
Creatine kinase (CK)
This is the first-line pharmacologic treatment for most inflammatory myopathies, given at 1 mg/kg/day.
High-dose prednisone (glucocorticoids)
This non-inflammatory myopathy presents with proximal weakness, normal or near-normal CK, hyperreflexia, tremor, and weight loss.
Hyperthyroid (thyrotoxic) myopathy
This purple or violaceous discoloration of the upper eyelids is considered pathognomonic for dermatomyositis.
Heliotrope rash
This autoantibody, found in immune-mediated necrotizing myopathy, is particularly associated with statin-triggered disease.
Anti-HMGCR
A 65-year-old man with classic dermatomyositis, 7 kg of unintentional weight loss, and anemia should have this test prioritized in his malignancy workup.
Colonoscopy
Name two first-line steroid-sparing agents used to maintain remission and reduce glucocorticoid toxicity in dermatomyositis.
Methotrexate and azathioprine
This condition causes proximal muscle stiffness and pain in the shoulders and hips with markedly elevated ESR but normal CK — and no true muscle weakness on exam.
Polymyalgia rheumatica (PMR)
This photosensitive dermatomyositis rash pattern covers the shoulders and upper back, named after an article of clothing.
Shawl sign
This autoantibody seen in dermatomyositis, especially in amyopathic forms, is strongly associated with rapidly progressive interstitial lung disease.
Anti-MDA5
This imaging modality is useful in inflammatory myopathies to identify muscle edema, guide biopsy site selection, and evaluate disease extent without radiation.
MRI of the affected muscles
This medication helps control skin manifestations and provides sun protection in dermatomyositis but is not effective for muscle disease.
Hydroxychloroquine
A patient on long-term corticosteroids develops slowly progressive proximal weakness with normal CK and normal EMG. What is the likely diagnosis?
Steroid-induced (glucocorticoid-induced) myopathy
A patient with classic DM skin findings but NO muscle weakness for ≥6 months and normal CK carries this specific subtype diagnosis.
Amyopathic dermatomyositis (ADM)
This autoantibody found in inclusion body myositis targets cytosolic 5'-nucleotidase 1A and helps support the diagnosis.
Anti-cN1A
In inclusion body myositis, the muscle biopsy classically shows endomysial inflammation plus these two pathologic ultrastructural findings.
Rimmed vacuoles and protein aggregates
Inclusion body myositis does not respond to immunosuppression. What is the cornerstone of management for these patients?
Physical therapy (supportive care)
This myopathy presents with myoedema on percussion, proximal weakness, delayed reflex relaxation (Woltman sign), and elevated CK. TSH is markedly elevated.
Hypothyroid myopathy
Skin biopsy in dermatomyositis classically shows this histopathologic pattern at the dermal-epidermal junction, along with mucin deposition and telangiectasia.
Vacuolar interface dermatitis
A patient has proximal weakness, mechanic's hands, Gottron papules, Raynaud phenomenon, arthritis, and ILD. Anti-Jo-1 is positive. Name all four non-Jo-1 autoantibodies that can also be seen in this syndrome.
Anti-PL-7, anti-PL-12, anti-EJ, and anti-OJ
A 55-year-old man with proximal AND distal weakness, slow progression over 12 months, mild CK elevation, and NO response to 6 weeks of high-dose prednisone should undergo this test as the most appropriate next step.
Muscle biopsy
A patient with refractory dermatomyositis who has failed methotrexate and azathioprine is considered for escalation. Name two biologic or advanced agents that may be used in this setting.
Any two of: Rituximab, IVIG, JAK inhibitors, calcineurin inhibitors, cyclophosphamide
A patient on atorvastatin develops proximal weakness with CK of 12,500 U/L. After 8 weeks off the statin, weakness persists and CK remains at 10,200 U/L. What is the specific diagnosis, and which two antibodies confirm it?