Psychosomatics 44:82-83, February 2003
© 2003 The Academy of Psychosomatic Medicine
Rectal Carcinoma With Dementia
Satheesh K. Kathula, M.D.,
Mallika Kamana, M.D., and
Sunita Mall, M.D., Miamisburg, Ohio
TO THE EDITOR: Limbic encephalitis is a syndrome consisting of severe memory deficits, depression, irritability, seizures, and dementia. Several cases of this entity have been described in association with lung, breast, testis, ovary, and renal cell carcinoma as a paraneoplastic phenomenon. An association between limbic encephalitis and colorectal cancer is extremely rare.1 We recently observed a case in which rectal cancer was diagnosed as the result of a clinical presentation of limbic encephalitis with rapidly progressive dementia.
Case Report
Mr. A, a 79-year-old man, was admitted to the hospital because of the rapid onset of loss of short-term memory, poor appetite, and weight loss. His symptoms had been present for about 8 weeks. He reported no history of prior medical problems and no alcohol or illicit drug use. He was alert but confused and disoriented as to time. He asked the same questions repeatedly in spite of their having been recently answered. A neurological examination revealed normal motor and sensory function but an unsteady gait. A neuropsychological assessment demonstrated global amnesia, low-average intelligence, paraphasic errors, impaired visuospatial perception, severe deficits in flexible thinking and reasoning, and markedly decreased attention span and short-term memory. The remainder of the examination was remarkable only for a hemoccult-positive stool. No mass was found upon rectal examination.
The results of examinations of serum electrolytes, CBC, liver function, antinuclear antibodies, cyanocobalamin and folic acid, thyroid-stimulating hormone, ceruloplasmin, and erythrocyte sedimentation rate were within normal limits. The result of a serology for syphilis and HIV was negative. Computerized tomographic (CT) and magnetic resonance imaging (MRI) scans of Mr. A's head were interpreted as normal. An analysis of CSF was remarkable for a lack of pleocytosis and a moderately elevated protein level without oligoclonal bands. Mr. A's CSF immunoglobulin G (IgG) was markedly elevated at 6.4 g/dl (0.8–1.8). Results of cultures of his CSF were found to be sterile. Results of an assay for anti-Hu antibodies and an EEG were negative.
Because of Mr. A's history of weight loss, CT scans of his abdomen and pelvis were performed to evaluate the possibility of on occult malignancy. A 6-cm mass was seen in the rectum, and multiple liver metastases were present. His carcino-embryogenic antigen level was elevated at 12.3 ng/dl (normal range=0.0–4.6). A colonoscopic biopsy of the rectal mass revealed well-differentiated adenocarcinoma. A low anterior resection was performed for palliation. Chemotherapy was administered, but death occurred because of progressive cancer, without improvement in cognitive function. An autopsy was not performed.
Discussion
Limbic encephalitis is a syndrome consisting of severe memory deficits, depression, irritability, seizures, and dementia. It was first described in 1960 by Brierley et al.2 In about 80% of the patients with paraneoplastic limbic encephalitis, the primary malignancy is small-cell lung cancer. In the remaining 20% of patients, the primary tumor may be in the breast, testis, ovary, or kidney.3 Limbic encephalitis in association with colorectal carcinoma is extremely rare. The pathogenesis of paraneoplastic limbic encephalitis is unknown. It has been hypothesized that paraneoplastic limbic encephalitis might result from antigen cross-reactivity of a host antitumor immune response within structures of the limbic system.1 Antineuronal antibodies, such as anti-Hu and anti-Ma, are very specific for paraneoplastic limbic encephalitis but are not sensitive.1 Paraneoplastic limbic encephalitis is only definitively diagnosed by neuropathological examination. However, the following criteria have been proposed to establish a clinical diagnosis of paraneoplastic limbic encephalitis:1
Short-term memory loss or symptoms suggesting involvement of the limbic system, interval of less than 4 years between the onset of neurological symptoms and the diagnosis of malignancy, exclusion of other neuro-oncological complications and at least one of the following: CSF with inflammatory changes such as pleocytosis, oligoclonal protein bands or increased IgG; MRI showing temporal lobe abnormalities; or EEG showing slow or sharp wave activity in temporal lobes.
Our patient met all four criteria for a clinical diagnosis of paraneoplastic limbic encephalitis. Other causes of similar symptoms, such as Alzheimer's dementia, herpes encephalitis, or Korsakoff's psychosis, were excluded by clinical and laboratory findings. A coincidental association of paraneoplastic limbic encephalitis and rectal cancer in this case cannot be excluded, but the rarity of limbic encephalitis and the temporal association of the two illnesses suggests that they were related.
In this unique case, rectal carcinoma presented as acute and rapidly progressive dementia with features of limbic encephalitis. Although it is admittedly rare, the presence of occult malignancy might be considered in instances of unexplained acute-onset dementia.
REFERENCES
- Gultekin SH, Rosenfeld MR, Voltz R, Eichen J, Posner JB, Dalmau J: Paraneoplastic limbic encephalitis: neurological symptoms, immunological findings and tumour association in 50 patients. Brain 2000; 123:1481-1494[Abstract/Free Full Text]
- Brierley JB, Corsellis JAN, Hierons R, Nevin S: Subacute encephalitis of later adult life, mainly affecting the limbic areas. Brain 1960; 83:357-368[Free Full Text]
- Voltz R, Gultekin SH, Rosenfeld MR, Gerstner E, Eichen J, Posner JB, Dalmau J: A serological marker of paraneoplastic limbic and brain-stem encephalitis in patients with testicular cancer. N Engl J Med 1999; 340:1788-1795[Abstract/Free Full Text]
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