Utility of Napsin A and Thyroid Transcription Factor 1 in Differentiating Metastatic Pulmonary from Non-Pulmonary Adenocarcinoma in Pleural EffusionKim J.-H.a · Kim Y.-S.a · Choi Y.-D.b · Lee J.-S.b · Park C.-S.b
aDepartment of Pathology, Jeju National University Medical School, Jeju, and bDepartment of Pathology, Chonnam National University Medical School, Gwangju, Korea
Objective: It was our aim to evaluate the usefulness of napsin A and thyroid transcription factor 1 (TTF-1) in the differential diagnosis of metastatic pulmonary and non-pulmonary adenocarcinomas (ACs) in pleural effusion. Study Design: A total of 84 pleural effusion fluid cell blocks were collected from metastatic ACs. There were 53 pulmonary ACs and 31 non-pulmonary ACs. Immunohistochemical staining was performed with antibodies against napsin A and TTF-1. Results: Napsin A was positive in 44/53 (83%) cases of pulmonary ACs, and TTF-1 was positive in 30/53 (57%) cases of pulmonary ACs. All non-pulmonary ACs were negative for napsin A and TTF-1. Napsin A showed a reactivity in >75% of the tumor cells in 36 of the 44 positive cases (82%), whereas TTF-1 showed a reactivity in >75% of the tumor cells only in 6 of the 30 positive cases (20%; p < 0.01). Poorly differentiated pulmonary ACs expressed napsin A (73%) more frequently than TTF-1 (53%), but this was not statistically significant (p = 0.45). Conclusion: We conclude that napsin A is superior to TTF-1 with regard to distinguishing between metastatic pulmonary and non-pulmonary ACs in cell blocks prepared from malignant pleural effusions.
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