[1827] Expression of Napsin A in Carcinomas from Various Organs.

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

Background: Napsin A has been recently reported as a highly sensitive and specific marker for identifying a primary adenocarcinoma of the lung. Its expression has also been demonstrated in papillary and clear cell renal cell carcinomas. In this study, we investigate the expression of napsin A in carcinomas from various organs using a single immunostaining system (Ventana XT).
Design: We immunohistochemically evaluated the expression of napsin A (Cat No. 760-4446; rabbit polyclonal; prediluted; Ventana) on 862 cases of carcinoma from various organs on tissue microarray sections. The staining intensity was graded as weak or strong. The distribution was recorded as negative (<5% of tumor cells stained), 1+ (5-25%), 2+ (26-50%), 3+ (51-75%), or 4+ (>75%).
Results: The immunostaining results are summarized in Table 1. Weak nuclear staining was also observed in 6 of 15 seminomas and 3 of 8 embryonal carcinomas in addition to cytoplasmic granular staining.

Table 1. Summary of immunostaining results

Tumor	Positive cases % (N)
Adenocarcinoma, lung	93% (50/54)
Squamous cell carcinoma, lung	5% (2/42)
Papillary renal cell carcinoma	69% (18/26)
Clear cell renal cell carcinoma	38% (20/53)
Adenocarcinoma, colon	29% (11/38)
Seminoma	50% (15/30)
Embryonal carcinoma	33% (8/24)
Yolk Sac tumor	50% (6/12)
Papillary carcinoma, thyroid	18% (8/45)
Adenocarcinoma, esophagus	17% (5/30)
Adenocarcinoma, stomach	6% (1/18)
Adenocarcinoma, pancreas	5% (3/56)
Urothelial carcinoma, bladder	5% (2/40)
Adenocarcinoma, prostate	0 (0/100)
Cholangiocarcinoma	0 (0/11)
Hepatocellular carcinoma	0 (0/18)
Ductal carcinoma, breast	0 (0/110)
Lobular carcinoma, breast	0 (0/53)
Follicular carcinoma, thyroid	0 (0/36)
Medullary carcinoma, thyroid	0 (0/10)
Adenocarcinoma, endocervix	0(0/17)
Papillary serous carcinoma, ovary	0 (0/15)
Adrenal cortical neoplasm	0 (0/24)

Conclusions: Napsin A is a sensitive and specific marker for differentiating lung adenocarcinoma from lung squamous cell carcinoma. However, napsin A is not an entirely specific maker for identifying a lung primary since it also expressed in a high percentage of renal cell carcinomas and germ cell tumors, and a significant number of carcinomas from the colon, thyroid and esophagus.
Category: Pulmonary

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 275, Tuesday Morning