Kim et al. D E Fig. 1. Immunohistochemistry demonstrates the MIC-2 antigen expression (D). Follow-up MRI reveals a new enhancing lesion abutting the anterior falx cerebri and left fovea ethmoidalis, and this suggests metastasis (E). and left fovea ethmoidalis was also noted (Fig. 1E). The FDG PET scan demonstrated increased metabolism in the mass, suggesting the recurrence of tumor. Radiation treatment was performed for the lesion. DISCUSSION Ewing’s sarcoma has a propensity to metastasize to the lung, bone and bone marrow. This tumor can also involve the CNS with a relatively low incidence (5 of 80 patients, 6.3%) being observed in a previous study (3). There are two reported principal modes of metastatic spread of Ewing’s sarcoma to the CNS. The first is direct extension from the skull, which may be the site of both primary and secondary Ewing’s sarcoma (4). Shuper et al. have reported that metastases to the brain directly extended from the skull in two of seven patients with brain metasta- sis (3). Alternatively, Ewing’s sarcoma may reach the CNS via hematogenous spread. In their case series, Shuper et al. also reported that five of seven patients with metastasis of Ewing’s sarcoma to the brain had parenchymal lesions that were separate from the skull and meninges, which suggested hematogenous spread of tumor. Other studies investigating CNS involvement of Ewing’s sarcoma have reported that spread through direct extension from the skull is more frequent than hematogenous spread (5, 6). Metastasis to the dura accounts for 9% of all CNS metastases (7). Various malignant neoplasms, including breast cancer, prostate cancer, melanoma, multiple myeloma, malignant lymphoma and leukemia, can secondarily involve the dura. However, dural metastasis of Ewing’s sarcoma has rarely been reported on. Only one 78 case of dural metastasis of Ewing’s sarcoma has been described in a report of an autopsy series (8). In that report, the lesion also involved the skull with diffuse, massive epidural and subdural plaque-like nodules. Therefore, the dural nodules might have extended from the skull, which is a frequent metastatic site for this tumor. A lack of imaging findings in that case makes it difficult to determine the origin of the dural lesion. In our patient, no abnormality in the skull abutting the metastatic tumor was noted on imaging or during surgery. Primary Ewing’s sarcoma of the central nervous system has rarely been reported on. The imaging characteristics of this rare tumor in an extra-axial location consist of high attenuation on CT and low signal intensity on T2-weighted MRI (4). Hemorrhagic components, dural extension and contrast enhancement were also reported. All three reported cases showed bone involvement, indicating that the origin of this rare tumor was the skull and not the dura (4). Another radiology report also showed similar imaging findings, but without skull involvement (9), which is very similar to the findings of our patient. It is not possible to say whether the resected tumor was a primary Ewing’s sarcoma or a secondary tumor because we did not confirm chromosomal translocation by performing fluorescent in situ hybridization. However, the subsequent recurrence might suggest that our patient had a metastatic tumor because primary Ewing’s sarcoma has been reported to show a more favorable outcome (10). Our initial differential diagnosis included more common tumors such as a meningioma. A schwannoma was also thought to be a possibility following catheter angiography due to the lack of blood supply from the meningeal Korean J Radiol 9(1), February 2008