Case Report
Copyright ©2011 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastrointest Oncol. Oct 15, 2011; 3(10): 144-147
Published online Oct 15, 2011. doi: 10.4251/wjgo.v3.i10.144
TTF-1 positive small cell cancers: Don’t think they’re always primary pulmonary!
Laurine Verset, Marianna Arvanitakis, Patricia Loi, Jean Closset, Myriam Delhaye, Myriam Remmelink, Pieter Demetter
Laurine Verset, Myriam Remmelink, Pieter Demetter, Departments of Pathology, Erasme University Hospital, Université Libre de Bruxelles, 1070 Brussels, Belgium
Marianna Arvanitakis, Myriam Delhaye, Department of Gastroenterology, Erasme University Hospital, Université Libre de Bruxelles, 1070 Brussels, Belgium
Patricia Loi, Jean Closset, Department of Digestive Surgery, Erasme University Hospital, Université Libre de Bruxelles, 1070 Brussels, Belgium
Author contributions: Verset L and Demetter P designed the research; Verset L, Remmelink M and Demetter P performed the research; Verset L, Arvanitakis M, Loi P, Closset J, Delhaye M, Remmelink M and Demetter P analyzed the data; Verset L and Demetter P wrote the paper.
Supported by The “Fondation Yvonne Boël” (Brussels, Belgium)
Correspondence to: Pieter Demetter, MD, PhD, Department of Pathology, Erasme University Hospital, Université Libre de Bruxelles, Route de Lennik 808, 1070 Brussels, Belgium. pieter.demetter@erasme.ulb.ac.be
Telephone: +32-2-5553115 Fax: +32-2-5554790
Received: January 4, 2011
Revised: September 21, 2011
Accepted: September 28, 2011
Published online: October 15, 2011
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.

Keywords: Thyroid transcription factor 1; Small cell carcinoma; Mixed endocrine-exocrine tumour; Common bile duct; Immunohistochemistry