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 Paget’s disease? Paget’s disease of bone is a chronic (long-lasting) disorder that causes bones to grow larger and become weaker than normal. Usually only one or a few bones have the disease. Many people with Paget’s disease do not have symptoms. However, the bone changes can cause: Bone pain. Misshapen bones. Broken bones (fractures). Problems in the joints near the bones with the disease. With treatment, many people can: Manage their symptoms. Improve pain. Control the effects of the disease.
What is reactive arthritis? Reactive arthritis happens when an infection causes joint pain and swelling. A bacterial infection in the digestive or urinary tract or the genitals usually triggers the condition, but arthritis symptoms typically do not start until a few weeks after you have recovered from the infection. The most common features of reactive arthritis are inflammation of the joints (especially the knees and ankles), eyes, and urinary tract, but not everyone gets all three, or they might not happen at the same time.
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 psoriasis? Psoriasis is a chronic (long-lasting) disease in which the immune system works too much, causing patches of skin to become scaly and inflamed. Most often, psoriasis affects the: Scalp. Elbows. Knees. The symptoms of psoriasis can sometimes go through cycles, flaring for a few weeks or months followed by times when they subside (or go into remission). If you have psoriasis, you may have a higher risk of getting other serious conditions, including: Psoriatic arthritis. Heart attack or stroke. Mental health problems, such as low self-esteem, anxiety, and depression.
What are growth plate injuries? The growth plate is the area of tissue near the ends of long bones in children and teens that determines what length and shape the bone will be once it is done growing. Each long bone— the thigh bone, the bones in the forearm, and the bones in the hands and fingers—has at least two growth plates, one at each end. Once your child has finished growing, the growth plates close and are replaced by solid bone. The growth plates are weak areas of your child’s growing skeleton, making it easier to injure them. Injuries
What is atopic dermatitis? Atopic dermatitis, often called eczema, is a chronic (long-lasting) disease that causes the skin to become inflamed and irritated, making it extremely itchy. Scratching leads to: Redness. Swelling. Cracking. “Weeping” clear fluid. Crusting. Scaling. In most cases, there are times when the disease is worse, called flares, followed by times when the skin improves or clears up entirely, called remissions. Atopic dermatitis is a common condition, and anyone can get the disease. However, it usually begins in childhood. Atopic dermatitis cannot be spread from person to person. No one knows what causes atopic dermatitis. Depending on
What is pachyonychia congenita? Pachyonychia congenita (PC) is a very rare genetic disorder that affects the skin and nails. Most people have thickened nails and calluses on the bottom of the feet. Painful calluses on the soles can make walking difficult. Because of the pain, some people rely on a cane, crutches, or a wheelchair to help with walking.