A study by Engels et al described four patients in whom open  and closed comedones  as  well as inflammatory acne lesions occurred 3-4 weeks after Cobalt-60 therapy for  a variety of malignancies. A previous history of acne  was not a prerequisite for the development of Out  of eighty patients treated with PUVA (psoralens and ultraviolet A) four developed perioral dermatitis, according to Nielson and Thormann, in two  cases together with acneiform eruptions localized to the forehead.60  Jones and Bleehen reported  one similar  patient. The lesions tend to be a mixture of noninflamed and small inflamed lesions.