title: Problems with the diagnosis of metastatic neuroendocrine neoplasms. Which diagnostic criteria should we use to determine tumor origin and help guide therapy?
abstract: Neuroendocrine neoplasms (NENs) can often present with metastatic disease before the primary tumor is discovered. Metastatic lesions are generally classified as well differentiated and poorly differentiated for prognostic and therapeutic purposes. In addition, for well-differentiated neuroendocrine tumors (WDNETs), pathologists are expected to determine the site of origin, if not already known, and grade the tumors. However, it is often difficult for pathologists to provide this information with certainty without knowing the site of tumor origin, as different criteria have been proposed by WHO for classification of gastrointestinal and pulmonary NENs. In this review, we will discuss the current classification and grading schema of NENs and their impact on clinical care, the differential diagnosis of NENs, the use of immunohistochemical stains that help identify tumor site of origin, and a proposed approach for the diagnosis and classification of metastatic NENs.
authors.affiliation: Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California.
authors.forename: Jamie
authors.initials: J
authors.lastname: Koo
authors.affiliation: Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, California. Electronic address: Deepti.Dahl@cshs.org.
authors.forename: Deepti
authors.initials: D
authors.lastname: Dhall
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D002454:Cell Differentiation; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000737:chemistry / Q000556:secondary* / Q000628:therapy; D060787:Neoplasm Grading; D055099:Neuroendocrine Cells / Q000737:chemistry / Q000473:pathology*; D018358:Neuroendocrine Tumors / Q000737:chemistry / Q000556:secondary* / Q000628:therapy; D011237:Predictive Value of Tests; D009626:Terminology as Topic
chemical_list: D014408:Biomarkers, Tumor
keywords: Carcinoid tumors; Diagnosis; Differential diagnosis; Grading; Neuroendocrine tumors; Site of origin