title: Poorly differentiated thyroid carcinoma: 5 years after the 2004 WHO classification of endocrine tumours.
abstract: Poorly differentiated thyroid carcinoma (PDTC) was originally described in 1983 but included in the WHO classification of thyroid tumours in the 2004 edition, only. The diagnostic problems encountered in the 5 years of application of the WHO criteria are reviewed here. A long debate is still going on about the nature of PDTC, its morphological diagnostic features, its clinical significance and its optimal therapeutic approach. A consensus conference held in Turin in 2006 confirmed the geographical differences among claimed classical forms of PDTC and suggested a diagnostic algorithm based on the presence of a solid/trabecular/insular growth pattern and of high-grade features, in line with the WHO definition of PDTC, capable to select tumours with a distinct aggressive clinical behaviour. This worked well for PDTC cases from mountain areas (e.g. Northern Italy), where most, if not all, thyroid carcinomas having high-grade features also share a solid/trabecular/insular pattern of growth. However, this scheme might be less easily applicable for American and Japanese cases, possibly due to heterogeneous architectural and cytological features; indeed some Authors still prefer to base their diagnostic work up on the recognition of high-grade features only, including mitotic index and necrosis, irrespective of the growth pattern.
authors: Department of Clinical and Biological Sciences at San Luigi Hospital, University of Turin, Regione Gonzole 10, 10043, Orbassano, Turin, Italy. marco.volante@unito.it
authors: Marco
authors: M
authors: Volante
authors: Mauro
authors: M
authors: Papotti
mesh_terms: D000230:Adenocarcinoma / Q000145:classification / Q000175:diagnosis / Q000473:pathology* / Q000648:ultrastructure; D006801:Humans; D013964:Thyroid Neoplasms / Q000145:classification / Q000175:diagnosis / Q000473:pathology* / Q000648:ultrastructure; D014944:World Health Organization