Context. - The immunohistochemical identification of thyroid transcription factor-1 (TTF-1) is regarded as the presence of a nuclear pattern of staining and is used to identify tumors of thyroid or pulmonary origin. Although there have been reports of cytoplasmic expression of TTF-1, the significance of this pattern has not been studied in detail. Objectives. - To determine the incidence at which cytoplasmic immunostaining for TTF-1 occurs and to analyze the diagnostic value of this pattern of immunoreactivity. Design. - Histologic sections of 361 consecutive cases of neoplasms stained for TTF-1 were reviewed, and those showing cytoplasmic staining in the tumor cells or in non-neoplastic cells were selected. Clinical correlation was obtained on the latter cases regarding the origin of the tumor. Setting. - An immunohistochemistry laboratory in a tertiary-care institution. Results. - The 361 tumors were obtained from 29 organ sites and corresponded to primary and metastatic neoplasms. Twenty-three (6.3%) tumors showed cytoplasmic staining for TTF-1. In 13 of these, the primary site of origin was established with certainty: 7 were lung carcinomas (3 primary lung adenocarcinomas, 1 primary large cell carcinoma, 1 metastatic small cell carcinoma to the liver, 1 metastatic adenocarcinoma to a neck lymph node, and 1 metastatic adenocarcinoma to thigh soft tissue), 3 colonic adenocarcinomas (2 metastases to vertebrae and 1 to lung), 1 metastatic breast ductal adenocarcinoma to femur, 1 metastatic laryngeal squamous cell carcinoma to liver, and 1 meningioma involving the orbit bone. There were 3 lung carcinomas with concomitant nuclear immunostaining. Nonneoplastic liver tissue was the most frequent non-tumoral tissue in which the cytoplasm stained with TTF-1 antibody. Conclusion. - Occasional cytoplasmic staining for TTF-1 in tumors is seen, but it is a nonspecific finding; when present, it should be disregarded for diagnostic purposes.
|Original language||English (US)|
|Number of pages||3|
|Journal||Archives of Pathology and Laboratory Medicine|
|State||Published - Feb 1 2003|
ASJC Scopus subject areas
- Pathology and Forensic Medicine
- Medical Laboratory Technology