Mongolian spots with involvement of mandibular area.

A 1-year-old boy had grayish pigmentation on the left side of his face over the area supplied by the mandibular branch of the trigeminal nerve. Upon further examination, the lesion was also found on the left side of the neck, shoulder, upper arm, right lower back and buttock. The pigmentation was uniform in intensity. This case report demonstrates that Mongolian spots can occur on the face in the area supplied by the mandibular branch of the trigeminal nerve. These spots should not be misdiagnosed as nevus of Ota.