Dural venous sinus tumour thrombus from metastatic thymoma

•Thymoma is the most common primary tumour of the anterior mediastinum.•Extrathoracic extension of disease in metastatic invasive thymoma is rare.•Intracranial metastasis causing tumour thrombus is a unique presentation of this disease.•Distinguishing tumour and non-tumour thrombus on imaging is critical for clinical management.