Extraskeletal myxoid chondrosarcoma of the masticator space in a pediatric patient.

Extraskeletal myxoid chondrosarcoma (EMC) is a malignant soft-tissue neoplasm rarely described in the head and neck region of children and adolescents. We describe a case of EMC affecting the masticator space and a literature review. A 13-year-old boy who presented a large painless, diffuse mass causing progressive midfacial asymmetry of 6 months duration. Histopathological evaluation revealed a multinodular lesion, containing scattered round vacuolated tumor cells dispersed in an abundant myxoid stroma, separated by fibrous septae. Immunohistochemical analysis revealed positivity for vimentin, neuron-specific enolase, and chromogranin. The Ki-67 labelling index was 42%. The patient was treated surgically with tumor resection followed by adjuvant local radiotherapy. The patient died 1 year after initial diagnosis due to locoregional tumor dissemination. EMC should be considered in the differential diagnosis of myxoid neoplasms in the head and neck region. Key words:Extraskeletal myxoid chondrosarcoma, masticator space, parapharyngeal space, immunohistochemistry, children.