title: TTF-1 positive small cell cancers: Don't think they're always primary pulmonary!
abstract: Thyroid transcription factor 1 (TTF-1) plays a key role in morphogenesis of the lungs and is expressed in up to 90% of pulmonary small cell carcinomas. This explains why this marker is frequently used in the search for the primary origin of metastatic endocrine tumours. Here we report on a TTF-1 expressing mixed endocrine-exocrine carcinoma of the common bile duct in a patient with pulmonary nodules that did not appear to be neoplastic. TTF-1 positivity in pulmonary and extrapulmonary neuroendocrine tumours is reviewed, and we conclude that TTF-1 expression in neuroendocrine tumours of the small-cell type are not uncommon at extrapulmonary locations. Therefore, immunohistochemistry for TTF-1 in such tumours should be interpreted with caution.
authors: Laurine Verset, Myriam Remmelink, Pieter Demetter, Departments of Pathology, Erasme University Hospital, Université Libre de Bruxelles, 1070 Brussels, Belgium.
authors: Laurine
authors: L
authors: Verset
authors: Marianna
authors: M
authors: Arvanitakis
authors: Patricia
authors: P
authors: Loi
authors: Jean
authors: J
authors: Closset
authors: Myriam
authors: M
authors: Delhaye
authors: Myriam
authors: M
authors: Remmelink
authors: Pieter
authors: P
authors: Demetter