Bilateral peripheral facial palsy (facial diplegia) has been repeatedly reported as a neurologic manifestation of acute myeloid leukemia but has not been reported as the initial clinical manifestation of myelomonocytic leukemia. A 71-year-old male developed left-sided peripheral facial palsy being interpreted and treated as Bell's palsy. C-reactive protein (CRP) and leukocyte count 4 days later were 2.5 mg/l and 16 G/l, respectively. Steroids were ineffective. Seven days after onset, he developed right-sided peripheral facial palsy. Three days later, CRP and leukocyte count were 234.3 mg/l and 59.5 G/l, respectively. Cerebrospinal fluid investigations revealed pleocytosis (62/3) and elevated protein (54.9 mg/dl). Two days later, pleocytosis and leukocytosis were attributed to myelomonocytic leukemia. Leukemic meningeosis was treated with cytarabine and methotrexate intrathecally. In addition, cytarabine and idarubicin were applied intravenously. Under this regimen, facial diplegia gradually improved. Facial diplegia may be the initial clinical manifestation of myelomonocytic leukemia, facial diplegia obligatorily requires lumbar puncture, and unilateral peripheral facial palsy is not always Bell's palsy. Patients with alleged unilateral Bell's palsy and slightly elevated leukocytes require close follow-up and more extensive investigations than patients without abnormal blood tests.
Keywords: Bell's palsy; chemotherapy; facial palsy; leukemia; leukemic meningeosis.