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Test Code NAPSN Napsin A Immunostain, Technical Component Only

Advisory Information

This test includes only technical performance of the stain (no pathologist interpretation is performed). If diagnostic consultation by a pathologist is required order PATHC / Pathology Consultation.

Shipping Instructions

Attach the green pathology address label and the pink Immunostain Technical Only label included in the kit to the outside of the transport container.

Specimen Required

Supplies: Immunostain Technical Only Envelope (T693)

Specimen Type: Tissue

Container/Tube: Immunostain Technical Only Envelope (T693)

Preferred: 2 unstained positively charged glass slide (25- x 75- x 1-mm) per test ordered; sections 4-microns thick.

Acceptable: Formalin-fixed, paraffin-embedded (FFPE) tissue block

Additional Information:

1. Information on accessing digital images of IHC stains and the manual requisition form can be accessed through this website:

2. Clients ordering stains using a manual requisition form will not have access to digital images.

3. Clients wishing to access digital images must place the order for IHC stains electronically. Information regarding digital imaging can be accessed through this website:

Useful For

Aids in the identification of primary lung adenocarcinoma

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
IHTOI IHC Initial, Tech Only No No
IHTOA IHC Additional, Tech Only No No

Method Name


Reporting Name

Napsin A IHC, Tech Only

Specimen Type


Specimen Stability Information

Specimen Type Temperature Time
TECHONLY Ambient (preferred)

Reject Due To








Wet/frozen tissue
Cytology smears
Nonformalin fixed tissue
Nonparaffin embedded tissue
Noncharged slides
ProbeOn slides

Clinical Information

Napsin A is an aspartic proteinase involved in the proteolytic processing of surfactant precursors in the normal alveolar epithelium. In normal tissues, napsin A is expressed in the cytoplasm of alveolar macrophages, type II pneumocytes, pancreatic ducts and acini, and in renal tubules. Napsin A has clinical utility for the identification of primary lung adenocarcinomas. Napsin A is also positive in a subset of thyroid and renal cell carcinomas (especially papillary types).


This test includes only technical performance of the stain (no pathologist interpretation is performed). Mayo Clinic cannot provide an interpretation of tech only stains outside the context of a pathology consultation. If an interpretation is needed, refer to test code PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case. All material associated with the case is required. Additional specific stains may be requested as part of the pathology consultation, and will be performed as necessary at the discretion of the Mayo pathologist.


The positive and negative controls are verified as showing appropriate immunoreactivity and documentation is retained at Mayo Clinic Rochester. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 855-516-8404.


Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.


No significant cautionary statements.

Clinical Reference

1. Chuman Y, Bergman A, Ueno T, et al: Napsin A, a member of the aspartic protease family, is abundantly expressed in normal lung and kidney tissue and is expressed in lung adenocarcinomas. FEBS Lett 1999 Nov 26;462(1-2):129-134

2. Suzuki A, Shijubo N, Yamada G, et al: Napsin A is useful to distinguish primary lung adenocarcinoma from adenocarcinomas of other organs. Pathol Res Pract 2005;201(8-9):579-586

3. Dejmek A, Naucler P, Smedjeback A, et al: Napsin A (TA02) is a useful alternative to thyroid transcription factor-1 (TTF-1) for the identification of pulmonary adenocarcinoma cells in pleural effusions. Diagn Cytopathol 2007 Aug;35(8):493-497

Method Description

Immunohistochemistry on sections of paraffin-embedded tissue.(Unpublished Mayo method)

Day(s) and Time(s) Performed

Monday through Friday

Analytic Time

1 day

Specimen Retention Time

Until staining is complete.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

88342-TC, primary

88341-TC, if additional IHC

LOINC Code Information

Result ID Test Result Name Result LOINC Value
70831 Napsin A IHC, Tech Only No LOINC Needed


If not ordering electronically, complete, print, and send an Immunohistochemical (IHC)/In Situ Hybridization (ISH) Stains Request Form (T763) (