Which of the following best describes "chronic, non-inflammatory musculoskeletal syndrome"?

Chronic, non-inflammatory musculoskeletal syndrome is best described by fibromyalgia. This condition is characterized by widespread musculoskeletal pain, fatigue, and tenderness in localized areas without the presence of inflammation typically seen in other musculoskeletal disorders.

Fibromyalgia's symptoms can often be exacerbated by stress, sleep disturbances, and environmental factors, which highlights its non-inflammatory nature. Unlike arthritis, which involves inflammation of the joints and can lead to joint damage, fibromyalgia does not cause inflammatory responses. Conditions like tendinitis and bursitis are specific inflammatory issues occurring in tendons and bursae, respectively, making them unsuitable answers for this description. Thus, fibromyalgia distinctly fits the category of a chronic condition characterized by pain without accompanying inflammation, affirming it as the correct choice.