[2060] Comparison of Napsin A Expression in Tumors with Polyclonal and Monoclonal Antibodies

Shaobo Zhu, Jianhui Shi, Kai Zhang, Haiyan Liu, Myra Wilkerson, Fan Lin. Geisinger Medical Center, Danville, PA

Background: Napsin A is a useful marker in identifying adenocarcinoma of the lung in a tumor of unknown origin. Our preliminary data and literature using a polyclonal antibody to napsin A demonstrated that it was a highly sensitive marker for pulmonary adenocarcinomas. However, expression of napsin A was also observed in a significant percentage of other tumors, including renal cell carcinomas, thyroid papillary carcinomas and esophageal adenocarcinomas. With the availability of a monoclonal antibody to napsin A, we compared expression of the polyclonal and the monoclonal antibodies in tumors from various organs using a single immunostaining system (Dako).
Design: Immunohistochemical evaluation of napsin A (1. Cat No. 760-4446, rabbit polyclonal, prediluted, Ventana; 2. Cat No. CM 338CK, mouse monoclonal, BioCare Medical) expression was performed on 1058 cases of tumors on tissue microarray sections. The staining intensity and distribution were recorded.
Results: The immunostaining results are summarized in Table 1. The sensitivity and specificity for the polyclonal and monoclonal antibody were 83.3% and 95.6%, and 72.6% and 97.9%, respectively.

Table 1. Summary of Immunostaining Results
TumorMonoclonal antibodyPolyclonal antibody
Lung ADC72.6% (61/84)83.3% (70/84)
Papillary RCC50% (8/16)75% (12/16)
Papillary thyroid CA15.2% (7/46)22.7% (10/44)
Clear cell RCC2.5% (1/40)12.5% (5/40)
Esophageal ADC0% (0/29)11.5% (3/29)
Ovarian tumors1.4% (1/72)6.9% (5/72)
Endocervical CA6.7% (1/15)6.7% (1/15)
Pancreatic CA0% (0/47)6.4% (3/44)
Lung neuroendocrine tumors7.3% (3/41)4.9% (2/41)
Lung squamous cell CA2% (1/49)2% (1/49)
Breast lobular CA0% (0/49)2% (1/49)
Germ cell tumors0% (0/79)1.25% (1/80)
Pancreatic endocrine tumors0% (0/16)0% (0/16)
Thyroid follicular CA0% (0/34)0% (0/34)
Colon ADC0% (0/36)0% (0/29)
Cholangiocarcinoma0% (0/11)0% (0/11)
Hepatocellular CA0% (0/18)0% (0/18)
Prostatic ADC0% (0/133)0% (0/133)
Breast ductal ADC0% (0/118)0% (0/118)
Urothelial CA0% (0/31)0% (0/31)
Gastric ADC0% (0/17)0% (0/17)
Melanoma0% (0/77)0% (0/77)
RCC-renal cell carcinoma; ADC-adenocarcinoma; CA-carcinoma

Conclusions: The polyclonal antibody to napsin A is more sensitive but less specific than the monoclonal antibody in identifying lung adenocarcinoma. A monoclonal antibody is the better choice for a tumor of unknown origin; whereas a polyclonal antibody is preferred for the distinction of primary lung ADC from squamous cell CA.
Category: Pulmonary

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 314, Tuesday Afternoon


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