keratoacanthoma

noun

ker·​a·​to·​ac·​an·​tho·​ma ˌker-ət-ō-ˌak-ˌan-ˈthō-mə 

plural keratoacanthomas also keratoacanthomata -mət-ə 

: a rapidly growing skin tumor that occurs especially in elderly individuals, resembles a carcinoma of squamous epithelial cells but does not spread, and tends to heal spontaneously with some scarring if left untreated