Added value of FDG PET in patients with suspected paraneoplastic syndrome; retrospective review of 102 patients

1525 Objectives Paraneoplastic syndromes are rare among the general patient population as well as those with cancer. Diagnosis of these disorders is challenging, with patients that typically present with characteristic syndromes and abnormal antibody levels. As such, diagnosis of these illnesses are a challenge which could present with classic symptoms, presence of onconeuronal antibodies, and presence of proven cancer. The role of [(18)F]-Fluorodeoxyglucose (FDG) positron emission tomography in the setting of suspected paraneoplastic syndromes has been inconclusive, with some studies supporting its use in all suspected cases and others stating its practical use in a handful of cases. The purpose of this study was to assess the added benefit of PET/CT in addition to other cross-sectional imaging in the initial diagnosis of paraneoplastic syndrome. Methods In this study, 102 patients with suspected paraneoplastic syndrome who underwent a whole body PET or PET/CT were selected for retrospective review. The majority of patients had their study between January 2010 and July 2014 with a handful of patients dating as far as 1999 Scans between 1999 and 2014 were reviewed. Patients also had serumSerum antibody analysis was reviewed through the Mayo Clinic to identify those who had positive antibodies to known associated paraneoplastic syndromes. This study including ed anti-hu, anti-voltage gated Ca channel, anti-nicotinic acetylcholine receptor, anti-Tr, anti-Ri, anti-Yo, anti-Ma1, anti-CRMP5, anti-amphiphysin, and anti-CDr-2 in the panel. Additional information on comorbid conditions, recent cross-sectional imaging, and follow up PET/CT were also collected. Of those selected, 47 were men with an age range between 12 and 80 (mean age of 53) and 55 were women with an age range between 18 and 84 (mean age of 52). Results Of the 102 patients, 11 were found to have positive antibodies known to be associated with paraneoplastic syndromes through a serum paraneoplastic antibody analysis from the May Clinic. Of the 84 patients who underwent conventional cross sectional imaging, 7 had a neoplasm detected on CT, US, or MR imaging (8.3%). Of these seven patients, four had accompanying findings on the PET examination (3.9% of total PET patients). These patients were considered to have a final diagnosis of a paraneoplastic syndrome. There were no patients who had a neoplasm whichthat was occult on cross sectional CT, US, or MR imaging that was seen on PET. However, upon review of all of the imaging studies, none of those patients exhibited any pertinent findings on PET/CT that had not been seen on a different cross-sectional imaging modality. The remaining 91 patients had negative imaging studies for paraneoplastic syndrome. Conclusions Whole-body PET/CT or PET/CT of 102 patients with suspected paraneoplastic syndromes did not reveal any additional findings malignancies in addition to those found on on top of routine cross-sectional imaging. Out of the 102 patients who had a scan, 11 patients were found to have a diagnosis of a paraneoplastic syndrome with no additional findings of disease on PET as opposed to other cross-sectional imaging modalities. In addition, none of the other 91 suspected cases had significant PET findings correlated to paraneoplastic syndrome.