Hypothalamic relapse of a cardiac large B-cell lymphoma presenting with memory loss, confabulation, alexia-agraphia, apathy, hypersomnia, appetite disturbances and diabetes insipidus.

A 37-year-old Hispanic man with a right atrial intracardiac mass diagnosed as diffuse large B-cell lymphoma (DLBCL) was successfully treated with surgery and chemotherapy. During 4 years, several total-body positron emission tomography and MRI scans showed no extracardiac lymphoma. On year 5 after the cardiac surgery, patient presented with sleepiness, hyperphagia, memory loss, confabulation, dementia and diabetes insipidus. Brain MRI showed a single hypothalamic recurrence of the original lymphoma that responded to high-dose methotrexate treatment. Correction of diabetes insipidus improved alertness but amnesia and cognitive deficits persisted, including incapacity to read and write. This case illustrates two unusual locations of DLBCL: primary cardiac lymphoma and hypothalamus. We emphasise the importance of third ventricle tumours as causing amnesia, confabulation, behavioural changes, alexia-agraphia, endocrine disorders and alterations of the circadian rhythm of wakefulness-sleep secondary to lesions of specific hypothalamic nuclei and disruption of hypothalamic-thalamic circuits.