The Utility and Limitation of Napsin a Study in Distinguishing Primary Lung Adenocarcinoma and Metastatic Lung Adenocarcinoma

Abstract

In the aspect of clinical approach, it is difficult to demonstrate the primary origin of cancer residing in lung tissue, especially for adenocarcinoma. This study was aimed to evaluate the potentiality of napsin A as a new specific marker for primary lung adenocarcinoma. We collected 115 cases originated from lung (squamous cell carcinoma: 30 cases; adenocarcinoma: 85 cases) to perform immunohistochemical study and reverse transcriptase PCR (RT-PCR) method. In addition, adenocarcinoma originated from colon, stomach, breast, ovary and uterine cervix were selected randomly for immunohistochemical study of napsin A. Significant expression of napsin A was detected by RT-PCR and in seventy-two out of eighty-five adenocarcinoma of lung by immunohistochemical stain. In contrast, negative expression was observed in squamous cell carcinoma. In other organ system, negative or low expression of napsin A is seen. Based on these results, it was concluded that napsin A was a useful marker in distinguishing primary lung adenocarcinoma from metastatic lung adenocarcinoma.