The disease is generally not difficult to diagnose based on the characteristics of the rash, site of onset, and development combined with a history of possible contact inquiries. Subclinical infections can be isolated or coexist with typical lesions and can be confirmed with a white acetate test or toluidine blue test. For latent infections, in situ hybridization or polymerase chain reaction (PCR) can be used to confirm the diagnosis. The following are some of the common diseases that need to be differentiated: 1, flat warts manifest as flat moist papules, often fused, the base is not narrow, syphilis spirochetes can be found, syphilis serology is positive. 3, penile pearly papules Most often seen in young adults, pearly translucent papules in the coronal groove, white, yellowish or red, cone-shaped, spherical or irregular, arranged in a row or several rows along the coronal groove, or even wrapped around a circle, no obvious symptoms. 4, Bowen-like papulosis rash often consists of multiple pigmented papules, can also appear single, scattered distribution or tendency to cluster, arranged into lines or rings, serious fusion into plaques, slow development (months or years), the disease is in situ squamous carcinoma, or from the development of condyloma acuminata. This disease is slightly more female, distribution sites mainly in the labia majora and minora, perianal. 5, sebaceous gland ectopia papules in the mucosa, no overlapping growth, mostly pale yellow. 6, sebaceous gland hyperplasia pale yellow papules, no tip, no spines, no overlap, no fusion. 7, parapapillary gland hyperplasia skin-colored or light red papules arranged in pairs on both sides of the foreskin tether, some of which are visible on the surface as mild spines. The papules are not narrow at the base, corn or pinhead in size, with no obvious conscious symptoms.