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 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 systemic lupus erythematosus (lupus)? Systemic lupus erythematosus (lupus) is a chronic (long-lasting) autoimmune disease that can affect many parts of the body, including the: Skin. Joints. Heart. Lungs. Kidneys. Brain. Lupus happens when the immune system, which normally helps protect the body from infection and disease, attacks its own tissues. This attack causes inflammation and, in some cases, permanent tissue damage. If you have lupus, you may have times of illness (flares) and times of wellness (remission). Lupus flares can be mild to serious, and they do not follow a pattern. However, with treatment, many people with lupus
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.