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-2TM (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.
|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)|