• 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

Immunohistochemical staining and microscopic examination

If requested, an interpretive report will be provided

Specifications

• 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

References

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.