A 36‐year‐old man with fourth ventricular mass

Abstract

A 36-year-old man presented with a 3-month history of intermittent progressive headache, nausea, vomiting and ataxia. No focal neurologic deficits were detected at the time of presentation. Brain MRI revealed inhomogeneous enhancing, lobulated border, isosignal intensity on T1-weighted image (TIW) ( Fig. 1), hypersignal intensity on fluid-attenuated inversion recovery (FLAIR)/T2W, showing a mass, measuring 4.0 × 3.5 × 3.5 cm. The mass appeared in the dilated fourth ventricle with extension to bilateral foramen of Luschka. The cerebellum appeared normal. The mass caused a pressure effect to the brain stem. The primary radiologic diagnosis was ependymoma. The patient underwent a total resection of the brain tumor. Intraoperative findings show grayish tumor attached to the anterolateral wall of the fourth ventricle. Postoperatively, the patient was completely disabled and totally confined to bed. Palliative radiotherapy was planned instead of chemotherapy due to poor performance status of the patient. Nuclear bone scan and CT scan of chest, abdomen and pelvis were negative for metastatic disease. Fourteen months after diagnosis, the patient is still alive without evidence of tumor recurrence. PATHOLOGICAL FINDINGSMacroscopically, the tumor was resected into multiple fragments of grayish tissues. Microscopically, sheets and compact nests of uniform small blue cells with scant cytoplasm were seen ( Fig. 2A). The nuclei were round to oval with finely dispersed chromatin and a small nucleolus. Mitotic figures were frequent. Immunohistochemically, the tumor demonstrated diffuse, strong membranous positivity for CD99 ( Fig. 2B) and nuclear positivity for Friend leukemia integration 1 transcription factor (FLI-1) (Fig. 2C). Focal positivity for glial fibrillary acidic protein (GFAP), synaptophysin and S100 protein was observed. Diffuse vimentin expression was detected. Integrase interactor 1 (INI-1) expression was preserved. Ki-67 labeling index was observed in approximately 40% of the tumor cells. Expression of AE1/AE3, CD45, CD117, desmin, epithelial membrane antigen (EMA), myogenin, placental alkaline phosphatase (PLAP), and terminal deoxynucleotidyl transferase (TdT) were not detected in tumor specimens. CYTOGENETIC ANALYSISFluorescence in situ hybridization (FISH) analysis revealed rearrangement of the Ewing sarcoma region (EWS) on chromosome 22q12 in 102/200 (51%) of tumor cells ( Fig. 3).