[A 67-year-old woman who mistook her daughter for a double: differential diagnosis of misidentification delusion].

A 67-year-old woman developed a misidentification delusion after a right-sided frontally located recurrent convexity meningioma was removed by surgery. After antipsychotic therapy had been established, the patient recovered and the delusions disappeared within a few weeks. A misidentification delusion is a fixed, false beliefabout the identity ofa person, an object, a place, or the time. In the differential diagnosis, psychiatric diseases and neurological diseases are prominent. Patients with a psychiatric disease are usually younger than 40 years, often have a psychiatric history, and usually have other psychotic symptoms like paranoid delusions and hallucinations. Brain tumours and temporal lobectomy have previously been described as a neurological cause of a misidentification delusion; the surgical removal ofa meningioma as such has not been previously described. In patients with a misidentification delusion, the connection between the perception of an identity and its accompanying emotions and memories is disturbed. This connection primarily takes place in the right side of the brain, which is in accordance with the location ofthe removed meningioma in the described patient.