Multifocal Ewing's sarcoma of the brain, calvarium, leptomeninges, spine and other bones in a child.

Ewing's sarcoma (ES) is a malignant osseous neoplasm that mostly affects children and young male adults, and usually presents as a solitary bony lesion. Multifocal ES of the central nervous system is extremely rare, with an incidence ranging from 1.1% to 4.3%. Clinically, ES may mimic osteomyelitis. In this report, we describe the case of an 11-year-old boy who had multiple calvarial, leptomeningeal, spinal and various other bony lesions of ES, which were diagnosed radiologically and histopathologically. To the best of our knowledge, this is the first time that multiple brain, calvarial and spinal lesions of ES in a single patient have been reported in the English-language literature. We discuss possible mechanisms and differential diagnoses for this rare pathology.