[596] TTF-1 and Napsin-A Frequently Positive in Esophageal and Pulmonary Adenocarcinomas: Dispelling Myths and Offering New Insights.

Kanwaljit S Aulakh, Cary Chisholm, VO Speights. Texas A&M Health Science Center – Scott & White Hospital, Temple

Background: Because the esophagus is situated in close proximity to the bronchial tree and lungs, invasive adenocarcinomas of these approximated anatomic structures can directly invade the other, creating a diagnostic challenge to determine which is the primary tumor. Tumors which metastasize to the esophagus include the thyroid, stomach, breast, ovary, and most commonly, the lung. Thyroid Transcription Factor-1 (TTF-1) protein is a reliable marker of pulmonary adenocarcinoma, being positive in up to 75% of these tumors. Despite its ubiquitous use in the evaluation of primary pulmonary tumors and distant metastases, its expression in primary esophageal adenocarcinoma has never been thoroughly investigated. We have found that the literature is entrenched with the presumption that esophageal adenocarcinomas lack TTF-1 expression, and subsequently, any TTF-1 positivity should preclude a diagnosis of primary esophageal adenocarcinoma. Other common and uncommon stains such as 34βE12, N-Cadherin, p63, Napsin-A, and IMP3 have also not been used in larger studies comparing these two entities.
Design: We applied these 6 stains (TTF-1, 34βE12, N-Cadherin, p63, Napsin-A, and IMP3) to primary esophageal and pulmonary adenocarcinomas that have been resected or biopsied and evaluate for immunohistochemical positivity. Immunohistochemical staining was scored semiquantitatively. The percentage of stained cells was graded from 0 to 4+: 0, no staining; 1+, 1%-25%; 2+, 26%-50%; 3+, 51%-75%; and 4+, 76%-100%.
Results:

Percent of Positive Cases

Adenocarcinoma Type	TTF-1	Napsin-A	N-Cadherin	P63	34βE12	IMP3
Pulmonary	92%	92%	42%	50%	96%	54%
Esophageal	88%	79%	0%	17%	92%	96%

Conclusions: According to our study, TTF-1 is frequently expressed in primary esophageal adenocarcinomas, contrary to presumptions that have been propogated in multiple literature sources broaching the subject. TTF-1, 34βE12, and Napsin-A fail to discriminate between esophageal and pulmonary adenocarcinomas due to frequent positivity in both tumor types. IMP3 is frequently positive in esophageal adenocarcinomas. Failure to stain with IMP3 should virtually exclude a diagnosis of esophageal adenocarcinoma. N-Cadherin did not stain any esophageal cases. Positive N-cadherin should also virtually exclude a diagnosis of esophageal adenocarcinoma.
Category: Gastrointestinal

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 92, Monday Morning