We experienced a case of small, round-cell malignant neoplasm diagnosed by touch smear cytology and histopathology when an open biopsy was performed in a 50-year-old Japanese woman. She was suspected of having a cervical spine tumor after surgery for cervical spine foraminal stenosis. After consent, the cervical spine tumor histologically diagnosed by an open biopsy was confirmed to be Ewing sarcoma (EWS) by genetic testing. EWS belongs to a group of small, round-cell tumors that are morphologically similar and often difficult to differentiate. After the open biopsy, the present patient received radiotherapy, and her plasma level of Pro-Gastrin-Releasing-Peptide was decreased (217.2 pg/ml before surgery to 30.3 pg/ml; reference value: 0 -80 pg/ml). We herein report the process for making the final diagnosis by focusing on the intraoperative cytology, histopathology, and immunohistochemical findings. Our diagnosis was validated by karyotyping and a fluorescence in-situ hybridization analysis.