What is acne? Acne is a common skin condition that happens when hair follicles under the skin become clogged. Oil and dead skin cells plug the pores, and outbreaks of lesions (often called pimples or zits) can happen. Most often, the outbreaks occur on the face but can also appear on the back, chest, and shoulders. For most people, acne tends to go away by the time they reach their thirties, but some people in their forties and fifties continue to have this skin problem.

What is alopecia areata? Alopecia areata is a disease that causes hair loss. In alopecia areata, the immune system attacks the structures in skin that form hair (hair follicles). Alopecia areata usually affects the head and face, though hair can be lost from any part of the body. Hair typically falls out in small, round patches about the size of a quarter. In some cases, hair loss is more extensive.

What is ankylosing spondylitis? Ankylosing spondylitis is a type of arthritis that causes inflammation in certain parts of the spine. Over time, this inflammation in the joints and tissues of the spine can cause stiffness. In severe cases, this may cause the bones in the spine to grow together, which can lead to a rigid spine that is difficult to bend. Many people with ankylosing spondylitis have mild episodes of back pain and stiffness that come and go. But others have severe, ongoing back pain and stiffness. Other symptoms also may develop if other areas of the body are affected

What is osteogenesis imperfecta? Osteogenesis imperfecta (OI) is a disease that causes your bones to break (fracture) easily. OI is also called brittle bone disease. Your symptoms may be mild or severe, depending on the type of OI you have.

What is osteonecrosis? Your bones are made up of living cells that need a blood supply to stay healthy. In osteonecrosis, blood flow to part of a bone is reduced. This causes death of bone tissue, and the bone can eventually break down and the joint will collapse. Osteonecrosis can happen to any bone, but most often it develops in the ends of long bones, such as the: Thigh bone. Upper arm bone. Less often, the bones of the elbows, ankles, feet, wrists, and hands are affected. When the disease involves part of a bone in a joint, it can

What is scleroderma? Scleroderma is an autoimmune connective tissue and rheumatic disease that causes inflammation in the skin and other areas of the body. This inflammation leads to patches of tight, hard skin. Scleroderma involves many systems in your body. A connective tissue disease is one that affects tissues such as skin, tendons, and cartilage. There are two major types of scleroderma: Localized scleroderma only affects the skin and the structures directly under the skin. Systemic scleroderma, also called systemic sclerosis, affects many systems in the body. This is the more serious type of scleroderma and can damage your blood

What is gout? Gout is a type of arthritis that causes pain and swelling in your joints, usually as flares that last for a week or two, and then go away. Gout flares often begin in your big toe or a lower limb. Gout happens when high levels of a substance called serum urate build up in your body. When this happens, needle-shaped crystals form in and around the joint. This leads to inflammation and arthritis of the joint. However, many people with high levels of serum urate will not develop gout. With early diagnosis, treatment, and lifestyle changes, gout

What are polymyalgia rheumatica and giant cell arteritis? Polymyalgia rheumatica and giant cell arteritis are closely linked inflammatory disorders. Some people have one of the disorders while others develop both of them. Polymyalgia rheumatica causes muscle pain and stiffness in the shoulders, upper arms, hip area, and sometimes the neck. Giant cell arteritis causes inflammation of arteries, especially those on each side of the head, scalp, and the aorta (the large artery that carries blood from the heart) and its main branches. The main symptoms of this disorder are: Headaches. Scalp tenderness. Jaw pain. Problems with your eyes, which may