Lack of FDG uptake in small cell carcinoma associated with ANNA-1 positive paraneoplastic autonomic neuropathy.

A 76-year-old smoker presented with profound weight loss due to gastrointestinal dysmotility associated with high levels of the paraneoplastic antibody ANNA-1. Serial computed tomography scans showed regressing subcarinal adenopathy, and positron emission tomography imaging showed mild fluorodeoxy-d-glucose uptake in subcarinal nodes, suggestive of benign disease. Diagnosis of small cell carcinoma was established by biopsy of mediastinal nodes. This case highlights the importance of a thorough search for malignancy in patients with high levels of circulating autoantibodies and suggests that benign-appearing imaging studies be interpreted with caution in patients with paraneoplastic autoimmune syndromes.