Primary intracranial extraskeletal myxoid chondrosarcoma in a teenager with unusual frontal location and surgical complications: A case report and literature review

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Primary intracranial extraskeletal myxoid chondrosarcoma (EMC) is rare and diagnostically challenging, with only sporadic pediatric and adolescent cases reported. The current study describes the case of a 17-year-old male presenting with an acute headache, nausea and emesis. Neuroimaging revealed a 7.2×5.2-cm hemorrhagic mass in the right frontal lobe with involvement of the anterior skull base. A gross total resection was achieved. Histopathology confirmed EMC with high-grade features, including loss of integrase interactor 1 (INI1) expression and a Ki-67 labeling index of 80%. The postoperative course was complicated by bacterial meningitis, which resolved with antibiotics. Adjuvant radiotherapy was delivered to the tumor bed and involved the dura at 66 Gy in 33 fractions without major toxicity. At the 3-month follow-up, there was no evidence of recurrence. This presentation, namely frontal-lobe localization in an adolescent and an aggressive immunophenotype with INI1 loss, is uncommon for intracranial EMC, which is more frequently described in middle-aged patients and posterior fossa sites. Molecular subtyping, which can inform targeted therapy selection, was not performed due to financial constraints. The diagnosis relied on multimodal integration of imaging, histology and immunohistochemistry; key mimics were disfavored by negative staining for glial fibrillary acidic protein, epithelial membrane antigen, desmin and S-100 protein. Given the pathological risk profile and the anticipated limited benefit of chemotherapy, systemic therapy was not pursued. The patient's long-term prognosis remains uncertain, and imaging surveillance is planned at 3- to 6-month intervals for 2 years and annually thereafter. This case highlights the importance of considering EMC in the differential diagnosis of young patients presenting with aggressive, hemorrhagic intracranial masses, particularly those with INI1 loss, and underscores the need for multimodal diagnostic approaches in such rare entities.

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