What is psoriatic arthritis? Psoriatic arthritis can occur in people who have psoriasis (scaly red and white skin patches). It affects the joints and areas where tissues attach to bone. The joints most often affected are: The outer joints of the fingers or toes. Wrists. Knees. Ankles. Lower back.

What is pachyonychia congenita? Pachyonychia congenita is a very rare disorder. It causes thick nails and painful calluses on the bottoms of the feet. In some cases, blisters also form on the palms of the hands.

What is tendinitis? Tendinitis is swelling and pain in a tendon, which is tissue that connects muscles to bones. It is a common condition, usually caused by repeated injuries to a tendon.

What is fibromyalgia? Fibromyalgia is a long-lasting or chronic disorder that causes muscle pain and fatigue (feeling tired). If you have fibromyalgia, you have pain and tenderness throughout your body. Sometimes you may have two or more chronic pain conditions at the same time, such as: Chronic fatigue syndrome. Endometriosis. Irritable bowel syndrome. Interstitial cystitis. Temporomandibular joint dysfunction (TMJ). Vulvodynia.