Pathology Outlines

Stains & molecular markers
NapsinA

Author: Nat Pernick, M.D.

Topic Completed: 1 June 2012

Revised: 5 February 2020

Copyright: 2002-2020, PathologyOutlines.com, Inc.

PubMed Search: Napsin A

Page views in 2019: 13,017

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Table of Contents

Cite this page: Pernick N. NapsinA. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainsnapsina.html. Accessed March 28th, 2020.

Definition / general

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

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 nonpulmonary (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)

Microscopic (histologic) images

Contributed by Andrey Bychkov, M.D., Ph.D.

Lung ADC

Images hosted on other servers:

Lung adenocarcinoma, compared with TTF1

Lung adenocarcinoma

Cerebellar tumor specimen

Lung squamous cell carcinoma

Various images

Cytology images

Images hosted on other servers:

Pulmonary ADC

Pulmonary SCC

SCC

ADC

PDC

Positive staining - normal

Type 2 pneumocytes (cytoplasm), alveolar macrophages (cytoplasm) (Hum Pathol 2010;41:20)

Positive staining - disease

Renal cell carcinoma: papillary (80%), clear cell (33%, Appl Immunohistochem Mol Morphol 2011;19:313)
Pulmonary adenocarcinoma
Ovarian clear cell carcinoma (Mod Pathol 2015;28;111)
Thyroid carcinoma: anaplastic (15%, Am J Surg Pathol 2013;37:1215), micropapillary (2 of 2), papillary (5% [2 cases, both were tall cell], Hum Pathol 2010;41:20), poorly differentiated (13%)

Electron microscopy images

Images hosted on other servers:

Type II pneumocytes