<s>[INST] context: Flash light pumped dye laser "Non blanching bosselated lesion on right side of the face suggests po wine stain" Po wine stain (PWS), also called nevus fiammeus, is a congenital, cutaneous vascular malformation involving post-capillary venules which produce a light pink to red to dark-red- violet discoloration of human skin. PWS occurs in an estimated 3 children per 1,000 live bihs, affecting males and females and all racial groups equally. There appears to be no hereditary predilection for PWS within families. There are no known risk factors or ways to prevent PWS. The most likely hypothesis for the development of PWS is the deficiency or absence of surrounding neurons regulating blood .flow through the ectatic post-capillary venules. - As a result, the blood vessels are unable to constrict normally and remain permanently dilated. - They are "non, blanching". PWS is a progressive vascular malformation of the skin -PWS remain throughout life; there is no involution. PWS are well demarcated and .1lat and grow propoionately in surface area with the child. In infants and young children, PWS are flat red macules. However, the lesions tend to darken progressively to purple and, by adult age. often become raised as a result of the development of vascular papules bosselated or nodules. These changes in color and contour are attributed to progressive ectasia of the abnornull dermal vascular plexus. - If left untreated, PWS often become incompatible with normal life due to the development of vascular nodules on the skin surface which can often bleed spontaneously with incidental trauma. For all of the above reasons, it is essential to begin treatment of PWS as early as possible. The treatment of PWS early will prevent the development of hyperophic component of the lession. - "The pulsed dye laser in conjunction with cryogen spray cooling ("dynamic cooling device" or "DCD") is now the treatment of choice for PWS". Yellow light produced by the pulsed dye laser penetrates up to 2 mm into the skin and is preferentially absorbed by hemoglobin within the dilated PWS blood vessels. The heat adsorbed within the vessel lumen causes blood vessel damage which is evidenced by intense purpura ("bruised" appearance of the skin). The purpura heals, later on and the lesion is cured. Several treatment sessions spaced at 4-8 week intervals are required for maximum efficacy. The number of treatments required .for maximum PWS fading can he variable and unpredictable. Treatment side effects are mainly limited to post-operative swelling and purpura, which generally resolves within 2 weeks. With the addition of cryogen spray cooling. the risks of scarring or changes in the normal skin pigmentation are minimal after pulsed dye laser therapy performed l an experienced physician. Multiple pulsed dye laser devices are now available for PWS treatment, each with its own unique wavelength and pulse duration. Changing the wavelength or pulse duration of the laser can result in substantial PWS fading not previously observed with single device therapy. Moreover, several devices are sometimes used during an extended treatment protocol in order to destroy vessels of different sizes. [/INST] question: Child with erythematous non blanching bosselated lesion on right side of face, Rx is aEUR' | options: A: >Erbium laser B: Nd-YAG laser C: >Flash light pumped dye laser D: >Q ruby laser | answer: C </s>