Which condition is not primarily a joint disease?

• A. Rheumatoid arthritis
• B. Osteoarthritis
• C. Fibromyalgia
• D. Gout

Answer: (C)

Fibromyalgia is not primarily a joint disease. It is a centralized pain amplification syndrome, characterized by widespread musculoskeletal pain, fatigue, unrefreshing sleep, and cognitive disturbances. Joints themselves typically do not have objective inflammation or structural damage; exams may show tenderness, but imaging and labs are usually normal. The core issue lies in how the nervous system processes pain, not in the joints.

In contrast, the other conditions involve joints as a central feature: rheumatoid arthritis is an autoimmune inflammatory disease with synovial inflammation and joint damage; osteoarthritis is a degenerative wear-and-tear process with cartilage loss and bony changes; gout is a crystal-induced inflammatory arthritis due to urate crystal deposition in joints. Fibromyalgia can coexist with these diseases, but its primary problem is altered pain processing rather than joint pathology.