The Role of p40 Immunostain in the Cytological Differential Diagnosis of Squamous Cell Carcinoma and Adenocarcinoma of the Lung
Xiangbai Chen, M.D., Yunhua Bao, M.D., Rebecca Wong, M.D., Katerina Politi, Ph.D., Lizhuo Jiao, M.D., Scott Gettinger, M.D., Robert Homer, M.D., Ph.D., David Chhieng, M.D., Guoping Cai, M.D.
Departments of Pathology and Internal Medicine, Yale School of Medicine, New Haven, CT, USA
INTRODUCTION
- Lung cancer is the leading cause of cancer death in the United States and worldwide, the majority of which are non-small cell carcinomas (NSCLCs) including adenocarcinoma (ADC) and squamous cell carcinoma (SQCC).
- In light of discovery of molecular alterations associated with lung ADCs and advent of targeted therapies, further subtyping of NSCLCs has profound therapeutic implications.
- Differentiation of lung ADCs from SQCCs may sometimes be difficult to achieve based on cytomorphology alone, especially for those poorly differentiated carcinomas.
- A panel of TTF-1/p63 immunostains is the current recommendation for differentiation of ADC from SQCC in small biopsies or cytological specimens.
- However, p63 positivity, though seen in virtually all SQCCs, can be seen in as high as 30% ADCs. Furthermore, only up to 70% of ADCs show positive TTF-1.
- Recently, p40, a new antibody that targets one p63 isoform - ΔNp63, has been shown a promising marker in identifying SQCC with high sensitivity and specificity on surgically resected tumors.
- In this study, we evaluated p40 immunoreactivity in the fine needle aspiration (FNA) specimens of lung ADCs and SQCCs.
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