Negative predictive value of pulmonary fine needle aspiration cytology

Percutaneous fine needle aspiration (FNA) for cytologic examination is an accepted and reliable technique for diagnosing neoplasia. It is less useful, however, in excluding that diagnosis. We performed a retrospective analysis of a consecutive series of pulmonary FNA specimens at Memorial Sloan-Kettering Cancer Center to determine the negative predictive value (NPV) of this technique in the setting of a large cancer hospital. Fifty-seven cases were studied. Six cases (10.5%) were initially diagnosed as negative but acellular and were not further analyzed, and another 6 were lost to follow-up; 24 cases (42.1%) were subsequently confirmed negative by tissue or clinical follow-up, and 21 of the cases (36.8%) were proven positive for malignancy by repeat aspiration, tissue diagnosis or clinical means. Of these 21 cases, 1 was misdiagnosed as negative, and review demonstrated malignant cells on the slide; 3 of the 21 cases should have been initially rejected as unsatisfactory, and 18 of the 21 contained material sufficient for a cytologic diagnosis but not representative of the lesion. On follow-up the false-negative cases showed primary adenocarcinoma, epidermoid carcinoma, lymphoma, metastatic breast carcinoma and metastatic sarcoma. Specific benign diagnoses were made on the initial cytologic preparation in three cases. No benign tumors were found. The NPV in our series was 53.3%, comparable to values in previous reports. The single largest factor contributing to false-negative diagnoses is sampling error, and we recommend repeat aspiration when no specific benign diagnosis is made. In addition, we suggest that the diagnoses of negative for malignant cells and insufficient for diagnosis or acellular be considered separate categories.