Background: Primary intracranial malignancies with extra-skeletal myxoid chondrosarcoma (EMC) features are extremely rare. EMC constitutes a distinct genomic entity characterised by reciprocal translocation of fusion genes, most commonly EWS RNA Binding Protein 1 (EWSR1) in 22q12 with Nuclear Receptor Subfamily 4 Group A Member 3 (NR4A3) in 9q2-q31.1. It is reported to have a high propensity for local recurrence and has potential for metastasis. So far in 28 years since its first description, only 17 cases of primary intracranial EMC were reported in literature. This would be the second case of intraventricular origin and first case from lateral ventricle.

Case presentation: A 27-year-old male presenting with complaints of headache, seizures and pain in neck was diagnosed to have a mass lesion in right lateral ventricle in Magnetic Resonance Imaging of brain. He underwent right parieto-occipital craniotomy with total excision of the lesion. Initial histopathological examination was reported as Ependymoma, WHO grade II. However, blocks and slides review with immunohistochemistry (IHC) markers revealed neoplastic aetiology with extensive myxoid changes. Hence, fluorescent in-situ hybridisation (FISH) testing was done with EWSR1 break apart probe, which demonstrated EWSR1 break apart signals. Therefore, correlating the clinical findings with morphology, IHC and FISH, the diagnosis of primary intracranial EMC was rendered. Patient received adjuvant external beam radiation of 54 Gy in 30 fractions to the post-op region. At 29-month follow-up, there was no evidence of disease recurrence.

Conclusions: Owing to the rarity of the condition, there are no standard treatment guidelines available for primary intracranial EMC. A combined treatment approach with surgery followed by adjuvant radiotherapy provides good local control with less morbidity.