[Multiple myeloma with numb chin syndrome as the initial manifestation].

The numb chin syndrome (NCS) is characterized by chin or lower lip numbness restricted to the distribution of the mental nerve (the distal trigeminal nerve). A case of multiple myeloma with polycythemia vera was diagnosed with NCS as the initial manifestation. A 73-year-old Japanese male was admitted to our hospital in April, 1993, because of paresthesia around the chin and lower lip. X-ray film showed multiple osteolytic lesions. According to serum and urine immunoelectrophoresis, lambda type Bence Jones protein was demonstrated. The bone marrow aspiration showed the normocellular marrow with 14.1% myeloma cells. He was diagnosed a suffering from multiple myeloma and was treated with melphalan and prednisolone. He is alive at present with resolution of NCS. We discussed pathogenesis, diagnosis, and treatment of NCS.