<prompt> True about Dermatomyositis is?Associated with HLA B27Bimodal age distributionNo involvement of jointsMyopathy precedes skin lesions in most cases  <response>: Ans. is b i.e., Bimodal age distribution Although it can occur at any age; there is a bimodal distribution with peaks between age 10 15 years in children and between 45 60 years in adults.Important factors associated with dermatomyositis It is the commonest type of inflammatory myopathy. More common in females. Associated with HLA types B8, B14 DR3. Juvenile DM is associated with HLA DR3. Production anti-Jo-1 antibodies is strongly associated with HLA DR3. DM is believed to be a microangiopathy affecting skin and muscles.. Other important factors associated with the causation of DM are drugs Hydroxyurea, D-penicillamine, NSAIDs, phenytoin, silicone breast implants bovine collagen implants. Skin manifestation are often non-specific initially and commonly precede the onset of myositis by at least several months. They are precipitated by UV light. 