18F-FDG PET/CT Findings in a Rare Case of Paraneoplastic Vestibulocerebellar Syndrome Associated With Isolated Antiamphiphysin Antibodies

Abstract

Paraneoplastic cerebellar degeneration (PCD) is an immune-mediated neurological disease characterized by adaptive immune response against onconeural antigens physiologically expressed in the cerebellum. It is characterized by presence of highly specific onconeural autoantibodies such as anti-Yo, anti-Hu, anti-Ri, and anti-Ma2 in the serum and cerebrospinal fluid as diagnostic biomarkers. Antiamphiphysin autoantibodyrelated paraneoplastic encephalitis is a less commonly seen autoimmune neurological disorder usually presenting as stiff person syndrome. We present an unusual case of isolated antiamphiphysin antibody-related PCD presenting as vestibulocerebellar syndrome with associated sensorineural hearing loss and sensory neuropathy. FDG PET helped in topographical localization of brain lesion along with early detection of extragonadal germ cell tumor in the retroperitoneum.

18F-FDG PET and MRI Evaluation of Paraneoplastic Limbic Encephalitis

“…14 Some autoantibodies may even produce atypical cerebellar encephalitis with corresponding FDG uptake. 15,16 No large studies have yet examined such patterns for anti-Hu, an intracellular antibody, but increased uptake in a unilateral MTL is consistent with current literature reports. Studies with larger series are needed to examine FDG uptake patterns of causative autoantibodies.…”

“…Different patterns of FDG uptake correlate with particular autoantibodies 14 . Some autoantibodies may even produce atypical cerebellar encephalitis with corresponding FDG uptake 15,16 . No large studies have yet examined such patterns for anti-Hu, an intracellular antibody, but increased uptake in a unilateral MTL is consistent with current literature reports.…”

Paraneoplastic Cerebellar Syndrome Presented as Cerebellar Hypermetabolism in a Patient With Occult Breast Carcinoma

“…1 The neoplasms most commonly involved are small cell lung cancer, gynecological (including carcinoma of the fallopian tube) and breast tumors, and Hodgkin lymphomas, [1][2][3][4][5] but it is also described in, for example, carcinoma of the tonsil, gastric adenocarcinoma, and extragonadal germ cell tumors. [6][7][8] An acute cerebellar syndrome is one of the most common neurological paraneoplastic syndromes and is most likely immune mediated. 1 Indeed, frequently, antineural antibodies in the cerebrospinal fluid and/or serum can be demonstrated.…”

Positron emission tomography in autoimmune encephalitis: Clinical implications and future directions

“…Anti‐amphiphysin encephalitis is a less common autoimmune neurological disorder. A patient presented as vestibulocerebellar syndrome with hypermetabolism in the vestibulocerebellum and adjacent vermis, while another patient developed limbic encephalitis showing hypermetabolism in the MTL 37,38 . Paraneoplastic limbic encephalitis (PLE) is a rare neurological disorder manifesting memory dysfunction, epilepsy, and psychiatric abnormalities.…”

“…A patient presented as vestibulocerebellar syndrome with hypermetabolism in the vestibulocerebellum and adjacent vermis, while another patient developed limbic encephalitis showing hypermetabolism in the MTL. 37,38 Paraneoplastic limbic encephalitis (PLE) is a rare neurological disorder manifesting memory dysfunction, epilepsy, and psychiatric abnormalities. Seventy percent of PLE cases occur in association with small cell lung carcinomas and testicular germ cell tumors.…”