Which condition primarily involves muscle inflammation?

The condition that primarily involves muscle inflammation is Polymyositis. This is an autoimmune disorder characterized by inflammation of the muscles, specifically the skeletal muscles, which can lead to muscle weakness and discomfort. In Polymyositis, the body’s immune system mistakenly attacks its own muscle fibers, resulting in inflammation and damage. This condition often affects specific muscle groups, particularly those closest to the trunk, such as the hips, thighs, and shoulders.

Understanding the pathophysiology behind Polymyositis helps clarify how this condition leads not just to symptoms of muscle weakness but also significant inflammation, which is a hallmark of the disease. The other conditions listed, while they may involve muscle-related issues, do not primarily focus on inflammation of the muscles themselves.