The earliest muscle to be involved in dermatomyositis is
Dermatomyositis (DM) is a long-term inflammatory disorder which affects muscles. Its symptoms are generally a skin rash and worsening muscle weakness over time.These may occur suddenly or develop over months.Other symptoms may include weight loss, fever, lung inflammation, or light sensitivity.Complications may include calcium deposits in muscles or skin. People with DM experience progressively worsening muscle weakness in the proximal muscles (for example, the shoulders and thighs).Tasks that use these muscles: standing from sitting, lifting, and climbing stairs, can become increasingly difficult for people with dermatomyositis .(quadriceps are first effected) Ref Robbins 9/e pg 172
Deltoid
Gluteal
Lumbricals
Quadriceps
Genetics