Depressive illness as a presentation of primary lymphoma of the central nervous system.

A 65-year-old man was referred from a medical unit for psychiatric assessment of a depressive illness associated with intermittent vomiting. No organic disorder was identifiable after the initial clinical examination and extensive investigations. A primary lymphoma involving the limbic system was eventually detected on repeat CAT scan and was confirmed at autopsy. This tumour, which is increasing in incidence, is notoriously difficult to diagnose and frequently presents with combined psychological and organic symptoms. It may be radiosensitive if detected early enough.