Contributed by Hirotomo Tanaka1, Daisuke Yamamoto1, Katsu Mizukawa1, Akiyasu Kanamori2, Norio Chihara3, Ryosuke Matsuoka4, Shigeo Hara4, Takanori Hirose4, Takashi Sasayama1, Eiji Kohmura1
1Department of Neurosurgery, 2Department of Ophthalmology, 3Department of Neurology and 4Department of Diagnostic Pathology, Kobe University Graduate School of Medicine, 7-5-2, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
CLINICAL HISTORY AND IMAGING
This 39-year-old-woman had suffered from a moderate grade fever of unknown origin and a headache for 9 months. A previous hospital could not find the cause of her symptoms; therefore, she came to our hospital. At the first visit to our hospital, she had no signs of meningeal irritation and no palpable lymph nodes in the neck or supraclavicular regions. And then, she complained dysesthesia of her limbs and decreased visual acuity in the left eye. The laboratory data showed hypoproteinemia, hypoalbuminemia, hypochromic microcytic anemia, positive antinuclear antibody, and elevated serum levels of CRP (13.12 mg/dl), IgG (2080 mg/dl), IgA (622 mg/dl), and Interleukin-6 (IL-6) (73.2 pg/ml). CSF protein level was elevated (126 mg/dl), there was an oligoclonal band and IgG index was increased, but anti-aquaporin 4 (AQP4) antibody was negative. Cell count in CSF was normal. MRI detected an enhancing mass in the left cerebellar hemisphere (Figs.1A, 1B). In addition, there was a mildly enhancing lesion in the cervical spinal cord (Fig. 1C, 1D). But intraorbital region and optic nerve had no abnormalities. The patient had a suboccipital craniotomy for tumor resection. The tumor was connected to the choroid plexus at the foramen of Magendie without dural attachment, and was totally removed. The postoperative course was excellent, and no further fever appeared from the day after surgery. Immediately after the resection, dysesthesia of her limbs and visual disturbance in the left eye was also improved. The enhancing lesion in the cervical cord was vanished. Serum levels of CRP (0.1 mg/dl), IgG (1180 mg/dl) and IL-6 (0.8 pg/ml) were decreased and the anemia was improved after surgery.
Histopathological examination of the surgical specimen revealed that the tumor cells, some of which contained vacuoles, were arranged in cell clusters and rows in the background of a myxoid matrix, resembling chordoma. (Figs. 1E, 1F) Furthermore, a meningothelial pattern was detected in a small portion of cells throughout the tumor (Fig. 1G). Some nuclear pleomorphism and focal necrosis were noted. Mitoses were noted in the most active areas, but invasion of the brain parenchyma was absent. In immunohistochemical examination, the tumor cells exhibited membrane staining for epithelial membrane antigen in focal areas (Fig. 1H). The tumor cells were positive for S100 protein (Fig. 1I), but negative for glial fibrillary acidic protein and cytokeratin. The CD20-positive B lymphocytes (Fig. 1J) and CD3-positive T cells (Fig. 1K) were infiltrated within the tumor. A few CD138-positive cells were revealed within the tumor. The tumor cells highly expressed interleukin-6 (IL-6) protein (Fig. 1L). In addition, the Ki-67 index of the tumor was very low (Fig. 1M). What is your diagnosis?