Numb chin syndrome as an initial symptom of acute lymphocytic leukemia: report of three cases.

This article describes three cases of acute lymphocytic leukemia that presented with mental neuropathy, or so-called "numb chin syndrome," as the initial symptom of the disease. This symptom heralded the initial progression of the disease in the first and second cases and the recurrence of the disease in the third case. In these cases tenderness in the mental foramen, percussion pain of the teeth, loosening and extrusion of the teeth, and radiographic abnormalities were also, if not always, observed in association with mental neuropathy. The radiographic abnormalities included a disappearance of the mandibular canals, an enlarged periodontal ligament space, a loss or thinning of the lamina dura, and a destruction of the alveolar crestal bone. This report indicates that oral manifestations can therefore occasionally play an extremely important role in the early recognition of acute lymphocytic leukemia. The unexplained oral abnormalities such as numbness of the chin and lower lip must thus be considered, potentially ominous indication of acute lymphocytic leukemia.