[A case of lung cancer with cranial neuropathy as the first sign of onset due to metastatic leptomeningeal carcinomatosis].

A 68-year-old man suffered right facial palsy and left deafness, however, his condition was considered to be idiopathic and he was followed. Three months later, bloody sputum and hoarseness caused him to be admitted to our hospital. An abnormal shadow was detected in the right upper lung field and adenocarcinoma of the lung with multiple brain metastases was diagnosed. He underwent gamma-knife radiosurgery for the brain lesions and subsequent systemic chemotherapy consisting of combined carboplatin and paclitaxel, which were not effective. Subsequently various neurological symptoms appeared, such as muscle weakness of the extremities, dizziness, and gait disturbance. Adenocarcinoma cells confirmed in the cerebrospinal fluid were similar to those in the obtained by transbronchial curetting. Whole-brain irradiation was performed, however, the neurological symptoms worsened and he died. Leptomeningeal carcinomatosis is difficult to diagnose while the patient is alive. It is thought that cranial neuropathy due to leptomeningeal carcinomatosis is a rare form of onset for lung cancer.