dermatomyositis

Dermatomyositis is one of a small group of rare conditions called the inflammatory myopathies, in which muscle stays inflamed over long periods and slowly weakens. The US National Institute of Neurological Disorders and Stroke describes most of these conditions as autoimmune disorders: the immune system that normally defends the body against infection turns instead on its own muscle fibres, blood vessels, connective tissue, organs or joints. Both children and adults are affected.

What sets dermatomyositis apart from the others is the skin. Alongside the muscle weakness it produces rashes on areas that are hard to hide, and those rashes are often long-lasting, itchy and disfiguring. The itch is among the most debilitating symptoms and among the hardest to treat. Until 2026 there was no medicine approved specifically for the disease, so it was managed with steroids and with drugs that damp down the immune system in general.