Papules are a common clinical condition in dermatology and are primary skin lesions, which are substantial damage to the surface of the skin with a limited elevation, usually less than 1 cm in diameter. Papules can be caused by a variety of diseases such as infection, physical injury, autoimmune diseases, herpetic dermatoses, vasculitis, etc. They may be caused by the deposition of metabolic products, limited proliferation of epidermal or dermal cellular components, or limited dermal cellular infiltration. The specific manifestations of papules are as follows: 1. shape: the shape of papules varies, the top shape can be divided into pointed, round, flat, or slightly depressed in the center, the base can be round, polygonal or irregular shape and other different shapes; 2. color: the color of papules varies, can be divided into red, purple, purple, yellow, white, dark brown and other colors, individual cases of surface In some cases, the surface may be accompanied by scales, affecting the local aesthetics; 3. Number: The papules can be single or densely distributed, and some patients may also be accompanied by itching, pain and other conscious symptoms. If the rash is between maculopapular rash and papular rash, it is called maculopapular rash, and if blisters or pustules appear on the basis of papular rash, it is called papular rash, pustular papule, etc.