Endocrine Abstracts

A 70 year-old male with a long standing history of IgG kappa paraproteinemia presented with sudden onset of confusional state. His friend had noticed short term memory lapses, behavioural changes, increased aggression and agitation for the last 3 months. He had developed proximal muscle weakness and pain. He was admitted to the hospital. He had no history of alcohol abuse, smoking or illicit drug use. He was not on any medication. He was under haematology surveillance for his paraproteinemia. His renal and liver function tests were normal. CSF revealed normal glucose, and marginally elevated protein. His CT scan showed a 3 cm thickened and hyperenhancing segment of distal ileum with enhancing nodes in the ileoclic mesentery. There were focal areas of low attenuations within the liver. The MRI scan showed enhancing soft tissue in the terminal ileum. There were multiple lesions in the mesentery and in the liver. He had 2 liver biopsies and histology confirmed a well differentiated metastatic NET. His N-methyl D-aspartate receptor antibodies (NMDA) and voltage gated potassium channel-complex antibodies (VGKC) were negative. His MRI scan of the brain did not show any space occupying lesion. His gut peptides were normal apart from chromogranin B that was elevated. He was treated with somatostatin analogues and steroids. His confusion improved and he is now clinically stable.

Discussion: A diagnostic criteria proposed by Gutelkin is used in the diagnosis of paraneoplastic limbic encephalitis. These are:

1. a clinical picture of short-term memory, loss, seizures, or psychiatric symptoms suggesting involvement of the limbic system,

2. an interval of < 4 years between the onset of neurological symptoms and the cancer diagnosis,

3. exclusion of other cancer-related complications (metastasis, infection, metabolic and nutritional deficits, cerebrovascular disorder or side-effects of therapy) that may cause symptoms of limbic dysfunction,

4. one of the following: CSF with inflammatory changes (pleocytosis, oligoclonal IgG bands); or MRI showing unilateral or bilateral temporal lobe abnormalities; and EEG showing slow- or sharp-wave activity in one or both temporal lobes.

Employing the above mentioned criteria, paraneoplastic limbic encephalitis secondary to midgut NET was considered as a possible explanation for his confusion and behavioural changes. He fulfilled 4 of the above criteria. In conclusion Paraneoplastic limbic encephalitis is a rare presentation in neuroendocrine tumors. There are only few cases reported. The diagnosis requires high index of clinical suspicion for the effective patient management.