Rare paraneoplastic syndrome of prostatic cancer: limbic encephalitis: a case report

Abstract

Introduction Limbic encephalitis is an autoimmune neurologic disorder, often of paraneoplastic origin, that seldom complicates prostatic tumors. The nonspecificity of symptoms makes the diagnosis sometimes difficult to establish. Prognosis is essentially determined by comorbidities and sensorineural and cognitive sequelae. Clinical case A 66-year-old Caucasian patient known to have prostatic small-cell neuroendocrine adenocarcinoma under hormonal therapy developed complex partial epileptic seizures associated with rapidly aggravating severe memory impairment. The tripod of autoimmune limbic encephalitis diagnosis was based on the clinical aspect of brain’s functional deterioration, electroencephalography aspect, and γ-aminobutyric acid type B anti-receptor antibody positivity. Clinical, diagnostic, and therapeutic management as well as evolutionary risks were further analyzed. Conclusion Limbic encephalitis is an extremely rare presentation of neurologic paraneoplastic syndromes. A better knowledge of this entity would help better manage diagnostic and therapeutic difficulties and reduce the risk of possible sequelae.

Paraneoplastic Syndromes in Neuroendocrine Prostate Cancer: A Systematic Review

“…Evans Syndrome [ 27 ], Limbic encephalitis [ 26 ], Hypercalcemia [ 19 ], CIPO [ 8 ], SIADH [ 24 , 25 ], dermatomyositis, and polycythemia [ 9 ] were the other seven PNS identified in our review. As with CS, the histological subtype in all of these syndromes was small-cell neuroendocrine cancer, except for dermatomyositis and polycythemia where it was large-cell carcinoma [ 8 , 9 , 25 , 26 , 27 ]. A previous history of prostate adenocarcinoma treated with ADT was identified in three out of the six cases, these patients passed away at a maximum of five months from their presentation.…”

“…Limbic encephalitis is a rare paraneoplastic neurologic syndrome that develops as an autoimmune response against neural antigens [ 26 ]. Several antibodies were identified in association with this syndrome, including type B gamma-aminobutyric acid receptor (GABA-B) antibodies, which are found in 5% of autoimmune encephalitis cases and carry a better prognosis than other antibodies [ 26 , 49 , 50 , 51 ]. The vague presenting symptoms of this syndrome, in addition to the profile of patients who are usually elderly with advanced malignancy, make the diagnosis challenging [ 26 ].…”

“…Several antibodies were identified in association with this syndrome, including type B gamma-aminobutyric acid receptor (GABA-B) antibodies, which are found in 5% of autoimmune encephalitis cases and carry a better prognosis than other antibodies [ 26 , 49 , 50 , 51 ]. The vague presenting symptoms of this syndrome, in addition to the profile of patients who are usually elderly with advanced malignancy, make the diagnosis challenging [ 26 ]. In a reported case of a 66-year-old male, a diagnosis of prostate adenocarcinoma was made.…”

“…After 13 years, he presented with generalized tonic–clonic seizures followed by postictal confusion. A diagnosis of limbic encephalitis was made with the biopsy showing small-cell prostate neuroendocrine cancer [ 26 ]. Management including treating the underlying tumor, as well as antiepileptics, IV steroids, immunotherapy, and plasmapheresis, may be necessary [ 26 ].…”