Frontal meningiomas are benign brain tumours known for their late onset. They may be presented by only psychiatric symptoms. Thus, the diagnosis at early stages can be missed or overlooked until the tumour causes neurological deficit.

We report the case of a 61-year-old man, receiving a treatment and a follow-up for bipolar disorder for 11 years. He has history of 3 major depressive episodes, 2 suicide attempts and a manic episode. The symptoms were initially well controlled by medication. Since 6 months, the patient started to experience atypical symptoms: he had presented disinhibited and aggressive behaviour, psychomotor instability, pyromania and self-neglect. The patient did not respond to treatment despite repeated adjustments. A frontal syndrome was suspected. Cerebral CT scan revealed an unexpected mass measuring 6.8 cm × 5.6 cm at the right frontal area, suggestive of a giant meningioma (Fig 1).

Generally, once diagnosed, psychiatric disorders are rarely revised. Consequently, “silent” tumours such as frontal meningiomas can be overlooked. Neuroimaging should be considered in case of new-onset psychiatric symptoms, atypical or change in clinical presentation.

The authors have not supplied their declaration of competing interest.