MULTIPLE PRIMARY CRANIAL EWING'S SARCOMA IN ADULTHOOD

Abstract

Ewing's sarcoma is a malignant bone tumor occurring most frequently in the long bones and flat bones as a solitary lesion during the first 2 decades of life. Ewing's sarcoma and peripheral primitive neuroectodermal tumor have recently been considered to be the same entity because of histological and molecular similarities. A 25-year-old man presented with swelling in the right parietal region. Magnetic resonance imaging scans showed 2 mixed intense mass lesions in the right parietal and left frontal areas with heterogeneous gadolinium enhancement. A computed tomographic scan revealed osteolytic changes of the inner calvarial bone. Ga-67 citrate scintigraphy demonstrated abnormal uptake in the right parietal and the left frontal areas consistent with the findings on magnetic resonance imaging scans. There was no uptake lesion beyond the cranium. The patient underwent surgical excision of the right parietal lesion. Histological examinations showed densely packed, small round cells with rosette formation. The cells had scanty clear cytoplasm, and regular vesicular and hyperchromatic nuclei. Electron microscopy showed little differentiation to neuronal tissue, indicating Ewing's sarcoma. After surgical treatment, conventional whole cranial irradiation of 40 Gy and chemotherapy were conducted. The tumor in the left frontal region disappeared. Follow-up examinations showed no evidence of recurrence 1 year after the surgery. Although quite rare, Ewing's sarcoma should be taken into consideration as a differential diagnosis of multiple cranial mass lesions in adulthood.