T cell acute lymphoblastic leukaemia presenting with sudden onset right oculomotor nerve palsy with normal neuroradiography and cerebrospinal fluid studies.

Leptomeningeal disease presenting with neurological dysfunction is not uncommon in leukaemia. However, it is often accompanied by abnormalities in cerebrospinal fluid (CSF) studies and/or neuroradiography. Here, the authors describe a case of a young patient presenting with sudden onset right oculomotor nerve palsy with normal neuroradiography and CSF studies, who was subsequently diagnosed to have T cell acute lymphoblastic leukaemia (T-ALL). This case highlights that neurological manifestations can be the initial presenting feature of T-ALL and can occur suddenly despite normal neuroradiography and initial CSF studies.