Initial case was retrieved from the scientific literature on 05 July 2012. The following is verbatim from the report: "An 80-year-old man presented in October 2010 with numbness and paresthesia in his right hand. These symptoms developed 2 weeks after receiving the influenza vaccine. In the subsequent 3 weeks, his right lower extremity and left foot were similarly affected. He also noticed a change in his voice, numbness of his face, and a "wobbly" gait. He reported no recent rashes, fever, neck stiffness, joint pains, or other systemic manifestations apart from a decrease in bowel movement frequency. He reported having fatigue and a diminished appetite without weight loss in the preceding year. A computed tomography scan of his chest, abdomen, and pelvis revealed a tumor in the right kidney. Laparoscopic resection demonstrated a renal cell carcinoma. He received no chemotherapy or radiation therapy and his symptoms improved after resection. His only other significant medical problems included hypercholesterolemia and hypertension. Physical examination was remarkable for a hoarse voice, ocular motility characterized by saccadic intrusions and impaired vertical gaze upwards, a mildly ataxic gait, and diminished sensation in his distal lower extremities. Cranial magnetic resonance imaging (MRI) performed on November 19, 2010, showed a fairly homogeneously enhancing lesion within the central pons, within a larger area of increased signal on the fluid-attenuated inversion recovery (FLAIR) images. The enhancement around the periphery of the lesion was somewhat punctate or "speckled". A biopsy specimen of the pontine lesion in December 2010 showed a reactive, T-cell-predominant, CD3-positive, lymphocytic infiltrate with scattered macrophages and microglial cells with few plasma cells. There were no microglial nodules identified. Occasional p53- and Ki-67-positive atypical astrocytes and gliosis were noted. No viral inclusions or infectious agents were seen on hematoxylin-eosin staining. No organisms were identified with Grocott methenamine silver staining and acid-fast bacteria staining, and viral immunohistochemistry findings for herpes simplex virus and human herpesvirus 8 were negative. An anti-cytokeratin (CAM 5.2) immunostain was performed because of the diagnosis of renal cell carcinoma but showed only nonspecific background staining. A luxol fast blue stain to access demyelination yielded negative results, and negative in situ hybridization findings were noted for Epstein-Barr virus encoded RNA. Flow cytometry failed to reveal a monoclonal B lymphocyte population. A lumbar puncture was performed in December and showed clear and colorless fluid. The cerebral spinal fluid cytology showed 5 white blood cells with 79% mononuclear cells; protein, 22 mg/dL; glucose, 72 ng/dL; and lactic acid, 2 mmol/L. The lactate dehydrogenase level in the cerebral spinal fluid was 26 IU/L. Venereal disease research laboratory test result was nonreactive. The patient's erythrocyte sedimentation rate was 5 mm/h and anti-nuclear antibody, anti-Sjogren antibodies, and other serologic screening test results were normal. A repeated brain MRI performed 1 month later showed little change. After pontine biopsy, the patient was given dexamethasone 4 mg, four times daily, which was continued for 1 week. Although no clinical improvement was evident in the interim, a repeated cranial MRI on January 5, 2011, showed decreased enhancement of the pontine lesion. Clinical and radiographic features improved in May 2011 when he received a course of intravenous methylprednisolone, 1 gram daily for 5 days, followed by oral prednisone 60 mg daily with gradual tapering. On June 23, 2011, a repeated MRI showed significant improvement in the contrast-enhancing lesions in the pons; however, the patient continued to have complaints of a glove-like paresthesia and had an ataxic gait. Methotrexate 15 mg weekly was initiated to accompany prednisone 20 mg every other day." The patient's outcome was not recovered. Documents held by sender: None.