dermatomyositis
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Introduction
Atrophy, edema or fibrosis of the skin accompanied by non-suppurative inflammation of striated muscle.
Dermatitis & polymyositis generally become apparent at the same time; however, skin or muscle involvement alone may occur initially.
* features distinguishing dermatomyositis from polymyositis
Etiology
- unknown
- autoimmune?
- often associated with malignancy in patients > 55 years of age (paraneoplastic variant, 20-25%)
- several types of maligancy
- ovarian cancer over-represented[4]
- amyopathic dermatomyositis variant described[4]
Epidemiology
- all ages
- adults: female > male
Pathology
- skin biopsy
- flattening of epidermis
- hydropic degeneration of epidermal basal cell layer
- fibrinoid deposits at dermal-epidermal junction & around upper dermal capillaries
- accumulation of acid mucopolysaccharides in dermis
- scattered inflammatory infiltrate (histiocytes, lymphocytes, plasma cells)
- CD4+ helper T-cells & B-lymphocytes
- perivascular antibody deposition*
- complement membrane attack complex (C5b-9) deposits*
- muscle biopsy
- microinfarctions, myofibril grouping[4]
- segmental necrosis within muscle fibers with loss of cross striations
- regenerating fibers may or may not be present
- histology indistinguishable from myositis due to other etiologies (i.e. connective tissue disease)
- perifascicular atrophy*
Genetics
- no familial association[4]
Clinical manifestations
- general
- acute or subacute with episodic or persistent progression
- malaise
- weight loss
- musculoskeletal
- proximal muscle weakness & stiffness (all cases)
- symmetric muscle weakness
- onset is acute or subacute[4]
- muscle pain (25%) is generally mild
- progresses over a period of weeks to months
- painless, no muscle tenderness[4]
- muscle weakness may involve trunk & neck, but spares face
- synovial & tendon friction rubs
- pharyngeal & respiratory muscle weakness
- dysphagia may develop from involvement of striated muscle of the pharynx
- proximal muscle weakness & stiffness (all cases)
- skin
- macular erythematous rash*
- may precede muscle weakness
- shawl sign: rash involves posterior neck, upper back, & shoulders
- V sign: rash involves anterior neck & chest
- malar erythema, may cross nasolabial folds
- heliotrope discoloration of the bridge of the nose*
- periorbital violaceous rash & poikiloderma
- periorbital edema (heliotrope suffusion of eyelids)
- heliotrope rash
- often presenting symptom
- pruritus may be intense[4]
- exfoliative dermatitis (poikiloderma)
- forehead, scalp, malar area, neck, upper chest, extensor surfaces (photosensitive distribution)
- holster sign (poikiloderma along lateral thigh)
- diffuse, scaly erythematous alopecia
- periungual telangiectasias
- cuticle overgrowth, Samitz sign, cuticle infarcts
- rash with papules & plaques over the knuckles (metacarpophalangeal joints) & proximal interphalangeal joints (Gottron's papules)*
- 'mechanic's hands' scaley, rough, dry, cracked horizontal lines on palmar & lateral aspects of the fingers in patients with anti-synthetase syndrome[4]
- peeling of the palms
- photosensitivity
- calcinosis (especially in children)
- signs of cutaneous vasculitis in adults generally occurs in association with occult malignancy
- macular erythematous rash*
- pulmonary
- basal interstitial pneumonitis & fibrosis (10%)
- interstitial lung disease may precede muscle weakness
- > 50% of patients with anti-Jo-1 Ab have interstitial pulmonary disease[4]
- aspiration pneumonia secondary to pharyngeal muscle weakness causes death in 10% of patients
- hypoventilation secondary to proximal myopathy is the most common cause of death
- weak cough
- dyspnea
- cardiac manifestations develop in 1/3 of patients
- dysphagia secondary to pharyngeal muscle weakness
- Raynaud's phenomenon
- lymphadenopathy
- splenomegaly
- arthritis is uncommon except in those with associated disease such as lupus erythematosus
* virtually diagnostic for dermatomyositis[4]
Diagnostic criteria
- proximal muscle weakness with 2 of 3 laboratory criteria
- elevated serum muscle enzymes
- characteristic electromyographic changes
- diagnostic muscle biopsy
- cutaneous manifestations*
- amyopathic dermatomyositis variant described[4]
Laboratory
- urine
- myoglobinuria
- increased 24 hour creatinine excretion (< 200 mg/24 hr)
- anemia
- hypergammaglobulinemia
- elevated erythrocyte sedimentation rate (ESR) & elevated C-reactive protein (CRP)
- increased serum muscle enzymes
- serum creatine kinase > 10-fold increase (hyperCKemia)
- CKMB index may be elevated by regenerating skeletal muscle
- serum lactate dehydrogenase increased
- serum aldolase increased
- serum aspartate transaminase (serum AST) increased
- serum alanine transaminase (serum ALT) increased
- serum creatine kinase > 10-fold increase (hyperCKemia)
- always check serum TSH when evaluating myopathy
- arterial blood gas (ABG)
- hypoxemia with pulmonary involvement
- hypercarbia with progressive hypoventilation
- serology (for classification, not diagnosis)[4]
- antinuclear antibodies (ANA) (80-95%)
- anti-Jo1 antibodies (23-36%)
- predictive of interstitial lung disease
- Raynaud's phenomenon
- anti PL-7 [threonyl tRNA synthetase protein, 80 kD] (4%)
- anti PL-12 [alanyl tRNA synthetase protein, 80 kD] (3%)
- anti Mi-2 (5-35%)
- anti-signal recognition particle (SRP) (54 kD protein complexed with 7 SL rRNA) (4-5%)
- anti PM-Scl (complex of 11 proteins 11-=120 kd) (8-12%)
- anti 56 kD RNP component (80%)
- anti RUVBL1 autoantibodies
- anti-MDA5 Ab
- skin biopsy
- muscle biopsy (proximal muscle, ie. shoulder, pelvis)
- not necessary with characteristic clinical & laboratory findings[4]
* features distinguishing dermatomyositis from polymyositis
Diagnostic procedures
- Electromyography:
- spontaneous fibrillation
- pseudomyotonic discharges
- positive sharp waves
- useful for excluding neuromyopathy
- if evidence of denervation, suspect coexisting neoplasm
- Pulmonary function testing with DLCO
- restrictive pattern (50%)
- hypoxemia
- evaluate for interstitial lung disease[22]
- Electrocardiogram
- evidence of myocarditis
- colonoscopy to evaluate for occult colorectal carcinoma[4]
- takes precedence over other testing[4]
- transvaginal ultrasound to evaluate for ovarian cancer if ascites
Radiology
- chest X-ray may show interstitial fibrosis
- computed tomgraphy (CT) of thorax, abdomen, pelvis
- evaluate for occult malignancy[4]*
- dermatomyositis may be the presentation of a paraneoplastic syndrome
- evaluate for interstitial lung disease (thorax)
- evaluate for occult malignancy[4]*
- magnetic resonance imaging of muscle can identify sites for muscle biopsy, aid in the diagnosis & help assess response to treatment[4]
- bone mineral density for patients treated long-term with glucocorticoids[4]
* essential
Complications
- associated malignancy[29]
- carcinoma of the breast, ovarian cancer, GI cancer, & bronchopulmonary carcinoma[4]
- most malignancies occur within 2 years of diagnosis
- may actually represent paraneoplastic variant of disease
- 15%-25% of adult cases associated with malignancy (6-fold increased risk of malignancy)[4][17]
- subcutaneous calcification especially in children
- perforation of bowel from vasculitis (rare in adults)
- glucocorticoid-induced myopathy
- new or worsening proximal muscle weakness despite normalization of muscle enzymes
- common causes of death
- cancer, infections, cardiovascular events, respiratory failure
Differential diagnosis
- lupus erythematosus
- mixed connective tissue disease
- steroid myopathy
- trichinosis
- toxoplasmosis
- microscopic polyangiitis
- polymyalgia rheumatica:
- no interstitial lung disease
- no rash characteristic of dermatomyositis
- rheumatoid arthritis:
- scleroderma:
- thickening & tightening of skin
- no rash characteristic of dermatomyositis
- polymyositis: absence of skin manifestations
- porphyria cutanea tarda
Management
- onset of dermatomyositis should prompt a workup of occult malignancy[29]
- see Complications: above & prognosis below
- refer to rheumatologist
- topical agents
- topical glucocorticoid
- tacrolimus ointment
- pecrolimus cream
- systemic agents
- glucocorticoid (prednisone) +/- other immunosuppressive agent
- prednisone alone for initial treatment of patients without severe myositis or extramucscular manifestations[4]
- start 0.5-1.0 mg/kg
- increase to 1.5 mg/kg if lower dose ineffective
- taper when serum enzyme levels normalize; serum creatine kinase, serum aldolase, serum LDH, serum AST
- use in conjunction with azathioprine 2-3 mg/kg/day
- onset of steroid myopathy occurs after 4-6 weeks of therapy
- high-dose immunoglobulin bolus therapy monthly diminishes prednisone dose to achieve or maintain remission
- 2/3 of patients respond to prednisone*
- prednisone alone for initial treatment of patients without severe myositis or extramucscular manifestations[4]
- methotrexate (1st add on)[4]
- azathioprine (alternative add-on)[4]
- mycophenolate
- cyclophosphamide (Cytoxan)
- rituximab
- hydroxychloroquine may helpful adjuctive agent for dermatitis, but of no benefit for myositis[4]
- other agents:
- cyclosporine-A
- chlorambucil
- intravenous immune globulin (refractory dermatomyositis)[16]
- therapy is generally required for at least 2 years after which many patients remain disease-free
- glucocorticoid (prednisone) +/- other immunosuppressive agent
- agents to improve blood flow
- physical therapy to maintain muscle strength
- supportive care
- prevention of glucocorticoid-induced osteoporosis
- screening for cancer
- sunscreen & protective clothing should be used
- prognosis
- response to treatment is generally good
- age is most important prognostic factor
- older age = worse prognosis[4]
- patients with malignancy & those with pulmonary involvement present special problems
- associated with malignancies
- treatment of neoplasm is often accompanies by improvement or resolution of dermatomyositis
- age-appropriate screening for cancer[4]
- additional testing for ovarian cancer may be appropriate
- CT or PET scan to look for underlying malignancy is not cost-effective unless the patient has additional risk factors[4]
More general terms
- autoimmune disease
- myositis (inflammatory myopathy)
- dermatitis
- connective tissue disease; soft tissue disease
More specific terms
Additional terms
References
- ↑ DeGowin & DeGowin's Diagnostic Examination, 6th edition, RL DeGowin (ed), McGraw Hill, NY 1994, pg 878
- ↑ Color Atlas and Synopsis of Clinical Dermatology, Common and Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 328-331
- ↑ Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 788-89
- ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26 4.27 4.28 4.29 Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, 16, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2006, 2009, 2012, 2015, 2018, 2022.
Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022 - ↑ Gerami P, Schope JM, McDonald L, Walling HW, Sontheimer RD. A systematic review of adult-onset clinically amyopathic dermatomyositis (dermatomyositis sine myositis): a missing link within the spectrum of the idiopathic inflammatory myopathies. J Am Acad Dermatol. 2006 Apr;54(4):597-613. Epub 2006 Jan 23. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/16546580
- ↑ Fathi M, Lundberg IE, Tornling G. Pulmonary complications of polymyositis and dermatomyositis. Semin Respir Crit Care Med. 2007 Aug;28(4):451-8. PMID: https://www.ncbi.nlm.nih.gov/pubmed/17764062
- ↑ Ytterberg SR. Treatment of refractory polymyositis and dermatomyositis. Curr Rheumatol Rep. 2006 Jun;8(3):167-73. PMID: https://www.ncbi.nlm.nih.gov/pubmed/16901073
- ↑ Iorizzo LJ 3rd, Jorizzo JL. The treatment and prognosis of dermatomyositis: an updated review. J Am Acad Dermatol. 2008 Jul;59(1):99-112 PMID: https://www.ncbi.nlm.nih.gov/pubmed/18423790
- ↑ Callen JP. Cutaneous manifestations of dermatomyositis and their management. Curr Rheumatol Rep. 2010 Jun;12(3):192-7 PMID: https://www.ncbi.nlm.nih.gov/pubmed/20425525
- ↑ Fardet L, Dupuy A, Gain M, Kettaneh A et al Factors associated with underlying malignancy in a retrospective cohort of 121 patients with dermatomyositis. Medicine (Baltimore). 2009 Mar;88(2):91-7 PMID: https://www.ncbi.nlm.nih.gov/pubmed/19282699
- ↑ Fathi M, Vikgren J, Boijsen M et al Interstitial lung disease in polymyositis and dermatomyositis: longitudinal evaluation by pulmonary function and radiology. Arthritis Rheum. 2008 May 15;59(5):677-85. PMID: https://www.ncbi.nlm.nih.gov/pubmed/18438901
- ↑ Gunawardena H, Betteridge ZE, McHugh NJ. Myositis-specific autoantibodies: their clinical and pathogenic significance in disease expression. Rheumatology (Oxford). 2009 Jun;48(6):607-12 PMID: https://www.ncbi.nlm.nih.gov/pubmed/19439503
- ↑ Lundberg IE, Forbess CJ. Mortality in idiopathic inflammatory myopathies. Clin Exp Rheumatol. 2008 Sep-Oct;26(5 Suppl 51):S109-14. PMID: https://www.ncbi.nlm.nih.gov/pubmed/19026152
- ↑ Selva-O'Callaghan A, Grau JM, Gamez-Cenzano C, Conventional cancer screening versus PET/CT in dermatomyositis/ polymyositis. Am J Med. 2010 Jun;123(6):558-62. PMID: https://www.ncbi.nlm.nih.gov/pubmed/20569766
- ↑ Walker UA. Imaging tools for the clinical assessment of idiopathic inflammatory myositis. Curr Opin Rheumatol. 2008 Nov;20(6):656-61 PMID: https://www.ncbi.nlm.nih.gov/pubmed/18946324
- ↑ 16.0 16.1 Amato AA, Griggs RC. Treatment of idiopathic inflammatory myopathies. Curr Opin Neurol. 2003 Oct;16(5):569-75. PMID: https://www.ncbi.nlm.nih.gov/pubmed/14501840
- ↑ 17.0 17.1 Hill CL, Zhang Y, Sigurgeirsson B et al Frequency of specific cancer types in dermatomyositis and polymyositis: a population-based study. Lancet. 2001 Jan 13;357(9250):96-100. PMID: https://www.ncbi.nlm.nih.gov/pubmed/11197446
- ↑ Airio A , Kautiainen H, Hakala M. Prognosis and mortality of polymyositis and dermatomyositis patients. Clin Rheumatol. 2006 Mar;25(2):234-9. Epub 2006 Feb 14 PMID: https://www.ncbi.nlm.nih.gov/pubmed/16477398
- ↑ Bernatsky S, Joseph L, Pineau CA et al Estimating the prevalence of polymyositis and dermatomyositis from administrative data: age, sex and regional differences. Ann Rheum Dis. 2009 Jul;68(7):1192-6 PMID: https://www.ncbi.nlm.nih.gov/pubmed/18713785
- ↑ Dalakas MC, Hohlfeld R. Polymyositis and dermatomyositis. Lancet. 2003 Sep 20;362(9388):971-82. PMID: https://www.ncbi.nlm.nih.gov/pubmed/14511932
- ↑ Marie I, Hachulla E, Hatron PY et al Polymyositis and dermatomyositis: short term and longterm outcome, and predictive factors of prognosis. J Rheumatol. 2001 Oct;28(10):2230-7. PMID: https://www.ncbi.nlm.nih.gov/pubmed/11669162
- ↑ 22.0 22.1 Morganroth PA, Kreider ME, Okawa J, Taylor L, Werth VP. Interstitial lung disease in classic and skin-predominant dermatomyositis: a retrospective study with screening recommendations. Arch Dermatol. 2010 Jul;146(7):729-38. PMID: https://www.ncbi.nlm.nih.gov/pubmed/20644033
- ↑ Zaba LC, Fiorentino DF. Skin disease in dermatomyositis. Curr Opin Rheumatol. 2012 Nov;24(6):597-601. PMID: https://www.ncbi.nlm.nih.gov/pubmed/22907594
- ↑ 24.0 24.1 Femia AN, Diamond HS (images) Medscape: Dermatomyositis http://emedicine.medscape.com/article/332783-overview
- ↑ 25.0 25.1 DermNet NZ. Dermatomyositis (images) http://dermnetnz.org/immune/dermatomyositis.html
- ↑ Iaccarino L, Ghirardello A, Bettio S et al The clinical features, diagnosis and classification of dermatomyositis. J Autoimmun. 2014 Feb-Mar;48-49:122-7. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/24467910
- ↑ 27.0 27.1 Charrow A, Vleugels, RA Cutaneous Ulcerations in Anti-MDA5 Dermatomyositis N Engl J Med 2019; 381:465. August 1, 2019 PMID: https://www.ncbi.nlm.nih.gov/pubmed/31365803 https://www.nejm.org/doi/full/10.1056/NEJMicm1816147
- ↑ 28.0 28.1 Ingram I FDA Approves IVIG for Dermatomyositis. Octagam 10% lands indication for adults following results of ProDERM trial. MedPage Today July 20, 2021 https://www.medpagetoday.com/rheumatology/generalrheumatology/93660
- ↑ 29.0 29.1 29.2 NEJM Knowledge+ Question of the Week. March 19, 2024 https://knowledgeplus.nejm.org/question-of-week/354/
Olazagasti JM, Baez PJ, Wetter DA, Ernste FC Cancer risk in dermatomyositis: a meta-analysis of cohort studies. Am J Clin Dermatol. 2015 Apr;16(2):89-98. PMID: https://www.ncbi.nlm.nih.gov/pubmed/25721032
Oldroyd AGS, Allard AB, Callen JP et al A systematic review and meta-analysis to inform cancer screening guidelines in idiopathic inflammatory myopathies. Rheumatology (Oxford). 2021 Jun 18;60(6):2615-2628. PMID: https://www.ncbi.nlm.nih.gov/pubmed/33599244 PMCID: PMC8213426 Free PMC article.
Cobos GA, Femia A, Vleugels RA. Dermatomyositis: An Update on Diagnosis and Treatment. Am J Clin Dermatol. 2020 Jun;21(3):339-353. PMID: https://www.ncbi.nlm.nih.gov/pubmed/32096127 Review. - ↑ NINDS Dermatomyositis Information Page https://www.ninds.nih.gov/Disorders/All-Disorders/Dermatomyositis-Information-Page