Growths on the anal opening could be anal warts. But they can be also hemorrhoids or tumors. Anal warts are caused by the Human papiloma virus (HPV). Condilomata acuminate are common genital warts caused by a specific type of HPV. If genital warts are not treated they can be cured spontaneously or more likely they could become larger and spread. You can visit a dermatologist for a precise diagnosis and to seek proper treatment.