Introduction
Dermatomyositis is a connective tissue disease where for the most part inflammatory and degenerative changes commonly occur in the affected muscles and skin.
By and large, it is an autoimmune disease, although surprisingly the precise mechanism of it is unknown. But what certainly is known is that cell mediated immune cells play a role in the infiltration and inflammation of muscles and skin.
To clarify, there also seems a cross reaction between certain tumors, autoimmune antibodies and the muscle antigens. In fact, there may be a shared antigen that makes dermatomyositis occur comparatively more often alongside certain tumors.
Hidden malignancies
In general, approximately 15% of men and less women with dermatomyositis have a hidden malignancy in their bodies. Uniquely, dermatomyositis is more common in women than in men with a ratio of 2 to 1. In general, sometimes a viral infection can be followed by the development of dermatomyositis. Specifically, picorna viruses have been implicated in a number of dermatomyositis cases. Notably, there are two age group peaks, the first one in childhood from age 5 to 15 and secondly, another peak at age 40 to 60 (Ref. 1).
References
1.The Merck Manual, 7th edition, by M. H. Beers et al., Whitehouse Station, N.J., 1999. Chapter 50.
2. WA Schmidt et al. Clin Rheumatol 2000;19(5):371-377.
3. A Sauty et al. Eur Respir J 1997 Dec;10(12):2907-2912.
4. R Queiro-Silva et al. J Rheumatol 2001 Jun;28(6):1401-1404.
5. J Wada et al. Clin Exp Immunol 2001 May;124(2):282-289.
6. Ferri: Ferri’s Clinical Advisor: Instant Diagnosis and Treatment, 2004 ed., Copyright © 2004 Mosby, Inc.
7. Rakel: Conn’s Current Therapy 2004, 56th ed., Copyright © 2004 Elsevier
