title: Neuroendocrine tumors: beyond the abdomen.
abstract: Several classification systems for neuroendocrine tumors (NETs) exist, which use variable terminology and criteria for grading and staging. This variability in terminology can cause confusion and difficulty in recognizing which tumors are, in fact, members of this heterogeneous group of malignancies. The largest group of NETs, the gastroenteropancreatic NETs, has been well described and characterized; however, there are less-recognized extra-abdominal NETs that can arise from nearly any organ in the body. In this article, the clinical features and imaging appearances of the extra-abdominal NETs will be reviewed, compared, and contrasted. This diverse group consists of paragangliomas, Merkel cell carcinomas, esthesioneuroblastomas, NETs of the lung, and medullary thyroid carcinomas. Recognition of these tumors as part of the larger group of NETs is important for understanding how best to approach imaging for their diagnosis, staging, and potential treatment. Familiarity with the computed tomographic and magnetic resonance imaging appearances and the role of radionuclide imaging of these heterogeneous groups aids in the correct diagnosis and in treatment planning.
authors.affiliation: From the *Department of Radiology, Oregon Health and Science University, 3181 S.W. Sam Jackson Park Rd., Vision Radiology; Pittsburgh, Pennsylvania; and †Department of Radiology, UCSF Medical Center and San Francisco VA Medical Center; 4150 Clement Street, San Francisco, California.
authors.forename: Melissa A
authors.initials: MA
authors.lastname: Jacobs
authors.forename: Stefanie
authors.initials: S
authors.lastname: Weinstein
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Hope
authors.forename: Rizwan
authors.initials: R
authors.lastname: Aslam
authors.forename: Judy
authors.initials: J
authors.lastname: Yee
authors.forename: Fergus
authors.initials: F
authors.lastname: Coakley
mesh_terms: D015266:Carcinoma, Merkel Cell / Q000175:diagnosis; D018278:Carcinoma, Neuroendocrine; D003952:Diagnostic Imaging; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis; D018358:Neuroendocrine Tumors / Q000175:diagnosis*; D010235:Paraganglioma / Q000175:diagnosis; D012878:Skin Neoplasms / Q000175:diagnosis; D013964:Thyroid Neoplasms / Q000175:diagnosis