A patient with atypical medullary breast cancer is described who presented
with symptoms of limbic encephalitis. The patient's serum and CSF contained
antibodies that reacted with the nervous system and the tumour. These anti
bodies recognised Ma2, a neuronal protein related to paraneoplastic limbic
and brainstem encephalitis in men with testicular tumours. This report high
lights the importance of testing for paraneoplastic antineuronal antibodies
in cases of unexplained limbic encephalitis and suggests screening for bre
ast cancer in women with antibodies predominantly directed to Ma2.