Neuroendocrine Neoplasms: A Case Report with Complete Reverse Mismatch and the Correlation with Differentiation Rate

Abstract

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors with an unpredictable expression that makes diagnosis and treatment difficult [1]. A 68-year-old man with history of 3-month weight loss and rapid gastric fullness comes to the clinic. The physician indicates abdominal tomography, ultrasound and endoscopy with biopsy of the upper digestive tract where an infiltrating lesion is discovered in the greater curvature of the stomach, immunohistochemistry reports carcinoid tumor. The patient is then sent to the Nuclear Medicine service seeking Peptide Receptor Radionuclide Therapy (PRRT). A PET/CT scan is performed using 68 Ga-DOTANOC, with another one a day later with 18 F-FDG to assess whether he is a candidate for said treatment. The images show a complete reverse mismatch pattern in the liver metastasis and primary gastric tumor found, making PRRT not an option due to a high degree of dedifferentiation and low expression of somatostatin receptors in such lesions. Keywords: Neuroendocrine neoplasms; 18 F-FDG;68 Ga-DOTANOC; Complete reverse mismatch.