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Stains

NapsinA

Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 26 June 2012, last major update June 2012
Copyright: (c) 2002-2012, PathologyOutlines.com, Inc.

Definition
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● A novel aspartic proteinase of the pepsin family involved in the maturation of surfactant protein B; found primarily in lung and kidney
● Lack of NapsinA expression in tumor cells may be poor prognostic marker in pulmonary adenocarcinoma (Lung Cancer 2012;77:156)

Uses by pathologists
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● Useful individually (Am J Surg Pathol 2012;36:396) or as part of panel (Arch Pathol Lab Med 2012;136:155, Appl Immunohistochem Mol Morphol 2012;20:350) to distinguish lung adenocarcinoma (positive) from squamous cell carcinoma (negative in tumor cells, but positive in hyperplastic type II pneumocytes and intra-alveolar macrophages entrapped within tumor cells)
● Useful as part of panel to classify poorly differentiated non small cell lung carcinoma on small biopsies (Am J Surg Pathol 2011;35:15), fine needle aspirates (Cytojournal 2012;9:10) or bronchial brushings (Cancer Cytopathol 2011;119:335)
● Superior to TTF1 in distinguishing primary lung adenocarcinoma from other carcinomas (except kidney), particularly primary lung small cell carcinoma and primary thyroid carcinoma (Arch Pathol Lab Med 2012;136:163)
● Superior to TTF1 in distinguishing metastatic pulmonary (positive) from non-pulmonary (negative) adenocarcinoma in cell blocks prepared from malignant pleural effusions (Acta Cytol 2011;55:266) or from fine needle aspirates (Cancer Cytopathol 2011;119:127)
● May help identify metastatic disease with unknown primary as originating in lung (Case Rep Oncol 2011;4:564)
● May help distinguish lung primaries from metastases to lung, as part of panel (Biotech Histochem 2012;87:30)

Micro images
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Kidney: normal and renal cell carcinoma


Lung: entrapped epithelium is NapsinA+


Lung adenocarcinoma: comparison with TTF1

           
Lung adenocarcinoma


Lung adenocarcinoma metastatic to cerebellum


Lung squamous cell carcinoma

   
Various images

Cytology images
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Various images

Positive staining - normal
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● Type 2 pneumocytes (cytoplasm), alveolar macrophages (cytoplasm) (Hum Pathol 2010;41:20)

Positive staining - disease
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● Renal cell carcinoma: papillary (80%), clear cell (33%, Appl Immunohistochem Mol Morphol 2011;19:313)
● Pulmonary adenocarcinoma

Electron microscopic images
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Type II pneumocytes and alveolar macrophages

End of Stains > NapsinA

Ref Updated: 6/26/12

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