Numb chin syndrome in acute lymphoblastic leukemia.

Numb chin syndrome is a sensory neuropathy of the inferior alveolar branch of the trigeminal nerve, characterized by unilateral numbness of the chin, the lower lip and the buccal and gingival mucosa. We report a girl with acute lymphoblastic leukemia of B-cell type who initially presented with numb chin syndrome resulting from skull base infiltration.