The codes are based on the total square centimeters treated, not body area, and per CPT Assistant August 2009, only one code is reported. I've copied and pasted the section from the CPT Assistant for you:
Year: 2009
Issue: August
Pages: 7&10-11
Destruction of Cutaneous Vascular Proliferative Lesions
Codes 17106-17108 are specific to the destruction of benign cutaneous vascular proliferative lesions, such as congenital port wine stains. Unlike the destruction of premalignant lesion codes 17000-17004, which are reported on the basis of the number of lesions, codes 17106-17108 are reported on the basis of square -centimeters treated. When these codes are used, only one code would be reported for the total square centimeters of the area treated. For example, if the treated area is 45 square centimeters, only code 17107,Destruction of cutaneous vascular proliferative lesions (eg, laser technique); 10.0 to 50.0 sq cm, would be reported.
If an extremely small vascular proliferative lesion (eg, 2 sq cm) is treated by various destruction techniques, it would be appropriate to report code 17106,Destruction of cutaneous vascular proliferative lesions (eg, laser technique); less than 10 sq cm.
Since the phrase “less than 10 square centimeters,” includes any and all measurements up to 10 sq cm; square centimeters, the use of modifier 52,Reduced Services, is not necessary. The use of codes 17106-17108 is not appropriate for treatment of lesions such as telangiectasia, cherry angioma, verruca vulgaris, and telangiectasia associated with rosacea.
Similar to the premalignant destruction codes (17000-17004) the cutaneous vascular proliferative lesion destruction codes (17106-17108) are not based on the specific anatomic location of the lesion.
Hope this helps!