Other variants of acne are relatively uncommon but in general are distinct and well-recognized entities. They may present in  the  very young (infantile  acne),  the elderly (senile comedones) or should be considered as a modulating factor in  a patient with 'conventional' acne (i.e. pomade or cosmetic acne). Among further conditions observed are naevoid acne and  acnes caused by drugs, chemicals (such as chloracne), physical states (such as friction or immobility),  self-mutilation (acne exoriee) and environment (tropical acne).