The rash is usually solitary and rarely multiple, with more than half of the lesions occurring on the scalp, face, and neck, and a few on the trunk. The lesion is an asymptomatic, firm nodule, sometimes stony and hard, located in the dermis or subcutaneously, rarely lobulated, occasionally cystic tumor, which may adhere to the skin, but the base is mobile and rarely ruptures, occasionally penetrating the epidermis and discharging its contents. Usually the diameter is less than 3 cm, but occasionally there are larger ones with normal surface skin appearance, which can also be red or light blue. In clinical practice, surgical excision is required, and pathological tests should be performed after excision to further clarify the diagnosis.