Depends on where it is. Hair loss and thickening/ crusting of the skin will occur on places where the body is frequently in contact with rough and hard surfaces. This might be on the elbow and even on the knuckles and over the hip. It's called a pressure sore or kennel sore. Technically, such things are perhaps called calluses. I doubt if it's infectious. Please feel free to provide any other pictures or details, or ask more questions. Try to give you a free consult.