[1810] Utility of Napsin A and TTF-1 Dual Stain on Paired Cytology and Surgical Specimens in Lung Carcinoma.

Beenu Thakral, Karan Saluja, Lin Liu. NorthShore University HealthSystem, Evanston Hospital, Evanston; University of Chicago Pritzker School of Medicine, Chicago, IL

Background: TTF-1 is a commonly used marker for diagnosing primary lung adenocarcinoma. Napsin A is an aspartic proteinase involved in maturation of surfactant protein B and is 80% positive in primary lung adenocarcinomas (ADC), and negative in squamous cell carcinoma (SCC) and small cell carcinoma (SmCC) of the lung. There is no literature on the expression of Napsin A on alcohol-fixed cytology smears.
Design: 21 paired samples (alcohol-fixed cytology smears and subsequent biopsy/excision specimens) from patients with lung carcinoma (primary or metastatic) from January 2006 to December 2008 were stained using Lung Adeno-2^TM (Napsin A + TTF-1) dual stain from BioCare Medical, CA.
Results: The dual staining results on biopsy/excision specimens demonstrated moderate positivity of Napsin A in 55% of primary lung ADC as compared to 73% TTF-1 strong positivity in these specimens.

Results of dual stain (Napsin A and TTF-1) on biopsy/excision specimens (21 patients)

Type of lung carcinoma	Positive TTF-1 (%)	Positive Napsin A (%)
ADC (n = 11)	8 (73)	6 (55)
a. Well to moderately differentiated (n = 5)	5 (100)	4 (80)
b. Poorly differentiated (n = 4)	2 (50)	1 (25)
c. ADC with sarcomatoid features (n = 1)	1 (100)	1 (100)
d. Mucinous ADC (n =1)	Negative (0)	Negative (0)
SCC (n = 5)	Negative (0)	Negative (0)
SmCC (n = 3)	3 (100)	Negative (0)
Poorly differentiated with neuroendocrine features (n = 1)	Negative (0)	Negative (0)
Metastatic ADC ( n = 1)	Negative (0)	Negative (0)

Of the dual stain performed on 7 paired cytology and subsequent biopsy/excision specimens, Napsin A and TTF-1 was moderately to strongly expressed in 4/4(100%) primary lung ADC, and negative in poorly differentiated ADC (n=1), SmCC (n=1) and SCC (n=1). We are in the process of completing the remaining 14 cytology smears. A 100% concordance was found between cytology and surgical specimens in the latter group.


Conclusions: Napsin A and TTF-1 dual stain reactivity was robustly positive with a good concordance between alcohol-fixed cytology smears and formalin-fixed specimens of primary lung ADC.
Category: Pulmonary

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 272, Tuesday Morning