Occult primary brain cancers manifesting in the aftermath of ischaemic and haemorrhagic stroke.

Of 77,484 patients with ischaemic strokes, 39 (1 in 2000) were associated with primary brain cancer; of 8409 with haemorrhagic strokes, it was 126 (1 in 66). In the background cohort, 205 (1 in 4000) had occult primary brain cancer. The multivariate stroke risk factor analysis showed that patients with occult primary brain cancer differed significantly from those without occult primary brain cancer indicating they might have stroke mimics rather than true strokes.Discussion and conclusions: Strokes associated with occult primary brain cancer tend to be stroke mimics rather than true strokes. Primary brain cancer is rare in patients with ischaemic stroke (1 in 2000); risk that misdiagnosis results in maltreatment is, therefore, very low. Occult primary brain cancers are mainly found among patients with haemorrhagic stroke; they are not uncommon (1 in 66) and should always be kept in mind.