Maxillary Mesenchymal Chondrosarcoma Affecting A Pediatric Patient: Case Report Showing Long-Term Follow-Up and Detailed Literature Review.

Introduction: Mesenchymal chondrosarcoma (MC) is a rare neoplasm representing about 3% of all chondrosarcomas and 0.1% of all head and neck cancers. To date, about 94 MCs affecting the jaws have been reported. Of them, 28 cases affected pediatric patients, which appear to have a favorable prognosis. Herein, we report an additional maxillary MC.Case Description: A 9-year-old boy was referred presenting an asymptomatic and expansive mass in the left maxilla with six months of evolution. CT scans revealed an expansile osteolytic lesion with granular irregularly shaped calcifications invading the nasal and orbital cavity and infiltrating the maxillary sinus with destruction of its posterolateral wall. Microscopic examination revealed dense sheets of small to medium-sized, poorly differentiated round cells arranged in hemangioperycitoma-like vascular pattern surrounded by nodules of mature cartilage. Immunopositivity for vimentin, S100, and CD99 were observed.Diagnosis and Treatment: The final diagnosis was MC. After neoadjuvant chemotherapy, partial maxillectomy was performed. Currently, with 13 years of follow-up, the patient remains well, with no evidence of recurrence or metastasis. Conclusion: The current case emphasizes that MC affecting pediatric patients with maxillary location appears to be associated with an indolent course and favorable prognosis. Supplementary Information: The online version contains supplementary material available at 10.1007/s12663-025-02480-w.