Napsin-A Expression in Small Cell Carcinoma of the Lung: A Cytologic Study.
Scott R Lauer, Cynthia Cohen, Michelle D Reid. Emory University Hospital, Atlanta, GA
Background: Napsin-A is an aspartic proteinase involved in surfactant protein B maturation. It is overexpressed in pulmonary adenocarcinomas (PA), and is a useful diagnostic alternative to thyroid transcription factor-1 (TTF-1). TTF-1 is also expressed by small cell carcinoma of the lung (SCCA) and facilitates its diagnosis. While Napsin-A expression has been examined in PA and pulmonary squamous cell carcinoma, its expression in SCCA of lung has not been fully evaluated. We examined Napsin-A expression in 36 cytologically confirmed cases of SCCA to determine if its expression paralleled that of TTF-1. To date ours is the largest cytologic series of lung SCCAs examined for Napsin-A expression.
Design: Thirty-six (36) primary and metastatic SCCAs diagnosed on fine needle aspiration (FNAB) or pleural effusion, with corresponding cell blocks, were identified. Patients ranged in age from 43 – 87 years (mean 57 years) with 20 males and 16 females. FNABs of mediastinal masses (n=5), liver masses (n=3), a subcutaneous nodule (n=1), lung masses (n=6), axillary, cervical and mediastinal lymph nodes (n=20) and 1 pleural effusion were immunostained with Napsin-A, TTF-1, pancytokeratin and at least one of three neuroendocrine (NE) markers (synaptophysin, chromogranin, CD56).
Results: The immunohistochemical results are summarized in Table 1.
|Positive||0 (0%)||35 (97%)||29 (81%)||17 (47%)||23 (64%)||35 (97%)|
|Negative||36 (100%)||1 (3%)||3 (8%)||10 (28%)||1 (3%)||0 (0%)|
|Not Tested||0 (0%)||0 (0%)||4 (11%)||9 (25%)||12 (33%)||1 (3%)|