Hep Par 1 expression is not rare in lung cancer

초록

Hepatocyte paraffin 1 (Hep Par 1) is known to be a suitable marker for the differentiation of hepatocellular carcinoma from metastasis of other malignancies. However, Hep Par 1 positivity was rarely reported in other tumor types including stomach and lung. We evaluated the incidence and staining pattern of Hep Par 1 in lung cancer using tissue microarray blocks. TMAs contained 529 lung cancer cases including 235 adenocarcinomas, 196 squamous cell carcinomas, 26 pleomorphic carcinomas, 23 adenosquamous carcinomas, 11 small cell carcinomas and 38 other types. Total 28 tumors were positive for Hep Par 1 (5.3%). Twenty tumors were adenocarcinomas (8.5%), 5 were pleomorphic carcinomas (19.2%), 2 were adenosquamous carcinomas (8.7%) and one was typical carcinoid tumor. Hep Par 1 expression was not detected in any of squamous cell carcinomas and high grade neuroendocrine carcinomas. Most of the adenocarcinomas showing Hep Par 1 positivity were acinar, solid or mucinous type and eight of them were negative for TTF-1. Alpha-fetoprotein was positive in only one case which was diagnosed as hepatoid adenocarcinoma of lung. Hep Par 1 positive and TTF-1 negative lung adenocarcinoma is not rare and the diagnostic difficulty may be encountered when discriminating primary lung adenocarcinoma from metastatic hepatocellular carcinoma.