Explosive eruption of pyogenic granuloma on the scalp due to topical combination therapy of minoxidil and retinoic acid.

A 55-year-old patient was treated with a combination of minoxidil and retinoic acid. After 1 month an explosive eruption of pyogenic granuloma appeared on the scalp. Despite redness and itchy reaction, caused only by the test containing both chemicals, histology did not give evidence of contact allergy.