Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody .Napsin A is pepsin like aspartic proteinase, a member of the novel aspartic proteinase of the pepsin family taking part in the proteolytic processing of surfactant precursors. Napsin A is expressed in the majority of pulmonary adenocarcinomas and is used as a specific marker for pulmonary adenocarcinoma. It is also expressed in Papillary renal cell carcinoma, endometrial and ovarian clear cell carcinoma, subset of cholangiocarcinoma.