Nevus of Ota is a congentinal pigmentary nevus condition that presents as blue or grey patch on face and can be unilateral or bilateral. It is a dermal melanocytic condition that can affect ocular and oral mucosal surfaces also.
Treatment: Cosmetic camouflague
Q switch Nd Yag Laser is the treatment of choice

Becker's nevus is an asymptomatic irregular tan to brown patch mostly located over shoulder, upper chest, back. Onset is mostly around puberty and irregular pigmented macules and plaques coalesce and expand in geographic configuration with dark hair within lesion. Considerable results >50% have been achieved with Er-Yag laser and Nd-Yag laser.