Napsin A by IHC

Alphabetical Test listing

Napsin A by IHC-12376 - Technical only, 12379 - Technical & Interpretation

Napsin A by IHC
12376 - Technical only, 12379 - Technical & Interpretation
  • All IHC stains will include a positive control tissue
  • Napsin A is a sensitive antibody for identifying adenocarcinoma of pulmonary origin; a recent study showed that sensitivity for Napsin A was up to 88% in pulmonary adenocarcinomas, vs 73% for TTF11
  • Napsin A is also expressed in type 2 pneumocytes, alveolar macrophages and plasma cells; since these cells can be entrapped in tumors, caution must be utilized in determination of true Napsin A reactivity
  • Napsin A is negative in most squamous cell carcinomas of lung
  • Napsin A has not been identified in small cell carcinomas
  • Staining for Napsin A has also been reported in papillary renal cell carcinoma, and papillary thyroid carcinomas (tall cell variant)1
  • This antibody should be used in a panel; the combined use of Napsin A and TTF1 is associated with increased sensitivity and specificity in identifying pulmonary adenocarcinomas
  • Napsin A has also been shown to stain about 80% of ovarian clear cell carcinomas5

Submit a formalin-fixed, paraffin embedded tissue block


Formalin-fixed, paraffin embedded (FFPE) tissue block


FFPE tissue section mounted on a charged, unstained slide


Ambient (preferred)

  • Unlabeled/mislabeled block
  • Insufficient tissue
  • Slides broken beyond repair
AHL - Immunohistochemistry
Mo - Fr
1 - 2 days

Immunohistochemical staining and microscopic examination


If requested, an interpretive report will be provided



  • Napsin A in an aspartic proteinase involved in the maturation of surfactant protein B
  • Its expression is regulated by TTF-1
  • This antigen is predominately expressed in the lung and kidney

 Staining pattern

  • Cytoplasmic staining


  1. Bishop JA et al: Napsin A and thyroid transcription factor-1 expression in carcinomas of the lung, breast, pancreas, colon, kidney, thyroid, and malignant mesothelioma. Hum Pathol. 2010;41(1):20-5.
  2. Ordonez NG: A word of caution regarding Napsin A expression in squamous cell carcinomas of the lung. Am J Surg Pathol 2012; 36(30):396-401.
  3. Mukhopadhyay S, Katzenstein AL: Subclassification of non-small cell lung carcinomas lacking morphologic differentiation on biopsy specimens: utility of an immunohistochemical panel containing TTF-1, Napsin A, p63, and CK5/6. Am J Surg pathol. 2011;35:15-25.
  4. Mukhopadhyay S, Katzenstein ALA. Comparison of Monoclonal Napsin A, Polyclonal Napsin A, and TTF-1 for Determining Lung Origin in Metastatic Adenocarcinomas . Am J Clin Pathol 2012;138 703-711.
  5. Yamashita Y, et al. Napsin A is a specific marker for ovarian clear cell adenocarcinoma. Mod Pathol 2015;28:111-117.
88342 - 1st stain
88341 - each additional stain