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amyopathic dermatomyositis; dermatomyositis-sine-myositis
Etiology:
- cormidities common
a) lung disease 19%, 39% of these fatal
b) malignancies 14%
- nasopharyngeal carcinoma, breast cancer, ovarian cancer
- may be triggered by sunlight [3]
Epidemiology:
- 20-30% of patients with dermatomyositis
Pathology:
- histopathologic myositis may or may not be present
Clinical manifestations:
1) skin lesions characteristic of dermatomyositis
2) delayed or absent muscle involvement
Laboratory:
1) anti-nuclear antibody present in 63%
2) anti Jo-1 antibody uncommon
3) serum muscle enzymes may be elevated
a) serum creatine kinase
- CKMB index may be elevated by regenerating skeletal muscle
b) serum lactate dehydrogenase
c) serum aldolase
d) serum aspartate transaminase (serum AST)
4) CADM-140 autoantigen (IFIH1)
- patients with anti-CADM-140 antibodies frequently develop life-threatening acute progressive interstitial lung disease [2]
Special laboratory:
- electromyography normal or may be abnormal [3]
- pulmonary function testing with DLCO
- evaluate for interstitial lung disease [4]
- evaluate for malignancy
Complications:
- pulmonary: interstitial lung disease
- malignancy
- see dermatomyositis
Management:
- glucocorticoids
- immunosuppressive agents
Notes: see dermatomyositis
General
dermatomyositis
References
- 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: 16546580
- UniProt :accession Q9BYX4
- Medical Knowledge Self Assessment Program (MKSAP) 16,17
American College of Physicians, Philadelphia 2012,2015
- 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: 20644033