Utility of Thyroid Transcription Factor-1 Expression in the Differential Diagnosis of Metastatic Adenocarcinoma of Serous Effusion Specimens Prepared Using the Cell Transfer Technique

Background/PurposePulmonary adenocarcinoma is a common malignancy of the pleural cavity. The cell transfer technique can be used to create multiple slides from a single smear. The goal of this study was to investigate the pulmonary origin of metastatic adenocarcinoma by evaluating the immunocytochemi-cal reactivity to thyroid transcription factor-1 (TTF-1) of slides of serous effusion specimens prepared by the cell transfer technique.MethodsIn 2001, a total of 76 archived serous effusion specimens containing adenocarcinoma from patients were used in this study. The primary site of metastatic adenocarcinoma was determined by a review of the medical records. The cell transfer technique was used to create multiple slides from a single Papanicolaou-stained smear. If more than 10% of the target cells reacted with perceptible intensity, nuclear staining was considered to indicate a positive TTF-1 result.ResultsPositive rates of TTF-1 for body fluids collected from patients with lung, stomach, ovarian, breast, colorectal and liver carcinomas were 41/50, 0/11, 0/6, 0/5, 0/2 and 0/1, respectively. Lung adenocarci-noma showed TTF-1 positivity in 82% of specimens, and all other adenocarcinomas had negative TTF-1 staining results.ConclusionThis study demonstrated that TTF-1 immunostaining in serous effusion specimens prepared using the cell transfer technique is a sensitive and highly specific marker for metastatic lung adenocarci-noma.