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.