A Patient with Mediastinal Mature Teratoma Presenting with Paraneoplastic Limbic Encephalitis

Abstract

A 22-year-old woman with a convulsion and impaired consciousness was transferred from a local psychiatric clinic to Oita University Hospital. She had no symptoms until July 2004, when she had fever and convulsive seizures and was diagnosed encephalitis. She underwent continuous infusion of thiamylal sodium for status epilepticus. Autonomic changes, such as tachycardia and increased sweating, were also seen. On neurological examination, she was in coma and status epilepticus, showing spastic paralysis and central hypoventilation. Tracheal intubation was performed, and she was put on mechanical ventilation. There were no evident endocrine or metabolic abnormalities. Antinuclear antibodies were negative. Her cerebrospinal fluid (CSF) pressure was 270 mm H2O. The fluid was clear and contained 26 cells/ l, glucose 72 mg/dl, protein 21.6 mg/ml, immunoglobulin G 6 mg/dl, and adenosine deaminase 1.5 IU/L. Microscopic examinations of the CSF for tumor cells and microorganisms were negative, and cultures yielded no growth. There were no marked elevations of antiviral antibody titers, including Epstein-Barr virus, herpes simplex virus, echo virus, and cytomegalovirus. A subunit of anti-N-methyl-D-aspartate receptor antibodies, anti-NR2B (glutamate receptor [GluR] epsilon-2) antibody, and antiNR2A (glutamate receptors [GluR] epsilon-1) antibody were positive in both serum and CSF. An anterior mediastinal tumor, 4.5 cm in diameter, was found on chest computed tomography scan (Figure 1). These findings suggested paraneoplastic limbic encephalitis associated with a mediastinal teratoma. The patient received corticosteroid therapy but the neurological symptoms continued. Serological tests showed hypothyroidism. The tumor was resected without combined resection of the thymus 10 months after the neurological symptoms appeared. Pathologically, the tumor was a mature teratoma with various tissue components, including skin, thymus, striated muscle, cartilage, bronchial glands and mucosa, and pancreas (Figure 2). The neurological symptoms improved dramatically postoperatively. The seizures disappeared, and the thiamylal infusion was gradually tapered over 3 weeks after surgery and discontinued. The patient was weaned from ventilatory support within 4 weeks after tumor resection. The patient is currently well at 7 years after surgery with no evidence of tumor recurrence.