Phototherapy of Acne Vulgaris
Acne vulgaris is a disease of sebaceous glands characterized by comedones, papules, pustules, and cystic lesions and has a complex pathophysiology including
Hyperkeratinization of the neck of the hair follicle and of the sebaceous duct resulting in obstruction
Increased production of sebum Increased free fatty acid content of sebum due to bacterial activity,
predominantly by propionibacterium acnes Often rupture of the follicle and release of sebum and keratin into
the dermis Inﬂammation An inﬂuence by hormonal and climatic factors and emotional
stress. Interest in using photons to interrupt or prevent this cascade of events
is usually attributed to the observation that acne often improves during summer and a belief, by physicians and patients, that sunlight helps to clear acne; there are no studies to support this belief. Sunlight is a very complex environment involving exposure to multiple wavebands of radiation, often in a relaxed or hormone-stimulating setting and it can induce tanning, which will camouﬂage acne lesions. A further complication is that about 20% of patients with acne are made worse by exposure to sunlight.