Summary

We describe a case of a man aged 41 years who presented with a history of generalised headaches for 1 week and an acute episode of tonic–clonic seizures. He had no history of medical illness, was non-smoker, with an extensive family history of haematological disorders. Initial CT brain with contrast did not show any abnormalities in brain parenchyma. X-ray and CT right shoulder showed shoulder dislocation secondary to trauma associated with seizure prior to hospital admission. Subsequently, MRA and MRV brain was arranged, which revealed extensive expansible occlusive filling defect dominating the middle of superior sagittal sinus with left frontal cortical and subcortical acute oedema. He was promptly started on anticoagulation therapy. Considering the unusual site and unprovoked nature of thrombosis, further investigations including JAK2 mutation were arranged which revealed latent myeloproliferative disorder. He was referred to haematology services for further follow-up and monitoring of latent myeloproliferative disorder.