Anti-collapsin response mediator protein 5 encephalitis masquerading as a low-grade brain tumour

Abstract

A 71-year-old woman presented acutely with seizures; her MRI suggested a low-grade glioma of the right temporal lobe. Over the preceding 18 months, she had developed progressive limb chorea and orofacial dyskinesia. Examination showed a predominantly amnestic cognitive profile. Initial investigations were normal, but later she was found to have antibodies to collapsin response mediator protein 5 (also called CV2). Her symptoms and neuroimaging abnormalities gradually improved without treatment. Four months later, surveillance imaging with (18)F-fluorodeoxyglucose-positron-emission tomography revealed a lesion confirmed by biopsy as a TX, N2, M0 small-cell lung cancer. This case is unusual for the strikingly unilateral neuroimaging abnormalities, which led to an initial misdiagnosis, and the spontaneous symptomatic improvement without treatment. In retrospect, the co-occurrence of paraneoplastic chorea, limbic encephalitis and neuropathy in the presence of an occult lung tumour make this almost a 'full house' of symptoms associated with antibodies to collapsin response mediator protein 5. It underlines the importance in clinical reasoning of avoiding the cognitive errors of premature closure and anchoring.

Autoimmune Encephalitis in a Patient with a Solitary Intracranial Plasmacytoma

“…Malignancies can cause several types of neurological syndromes, such as limbic encephalitis, encephalomyelitis, and rapidly progressive cerebellar syndrome (4). Small-cell lung cancer (SCLC) is most often associated with autoimmune encephalitis, but many other neoplasms such as breast cancer, thymoma, ovarian teratoma, and Hodgkin's lymphoma have been identified (1,(5)(6)(7)(8). Malignancy-induced autoimmune encephalitis is associated with onconeural autoantibodies against intracellular antigens (anti-Hu, anti-Ma1, anti-CV2) and cell membrane antigens [anti-N-methyl-Daspartate receptor (NMDAR), anti-α-amino-3-hydroxy-5methyl-4-isoxazole-propionic acid receptor (AMPAR), anti- Although hematological cancers such as lymphoma are known to cause paraneoplastic limbic encephalitis, plasma cell neoplasms co-occurring with autoimmune encephalitis have not been reported (9).…”