Small cell carcinoma versus other lung malignancies: diagnosis by fine-needle aspiration cytology

When a diagnosis of small cell carcinoma is reached in a patient with a lung mass, a surgical treatment approach is no longer considered and chemotherapy becomes the treatment of choice. The aim of this study is to compare the diagnostic accuracy of fine-needle aspiration cytology in the diagnosis of small cell carcinoma with the diagnoses of other lung malignancies. The capacity of this technique to distinguish between these two categories is assessed.

Two hundred fifty-nine consecutive transthoracic fine needle aspirations of lung tissue from 235 patients with histologic diagnosis of malignancy were reviewed. The aspirates were performed over a 10-year period at the University of Miami/Jackson Memorial Medical Center, Miami, Florida. Two hundred and forty-two fine-needle aspirations from 221 patients yielded satisfactory smears and were included in the study. Fourteen patients were excluded. The cytologic diagnoses were classified into 5 categories: 1) small cell carcinoma (18 smears, 7%); 2) other lung malignancies (158 smears, 65%); 3) suspicious for malignancy (19 smears, 8%); 4) inflammatory process (7 smears, 3%); and 5) negative for malignancy (40 smears, 17%).

The histologic diagnoses were divided into two groups: small cell carcinomas (29 smears, 12%), and other lung malignancies (213 smears, 88%). The efficiency of fine-needle aspiration cytology in the diagnosis of these two groups was 96% versus 88%, respectively, with an equal specificity of 100%, and a sensitivity of 67% versus 81%. Once the diagnosis of malignancy was established, fine-needle aspiration cytology was found to be highly accurate in distinguishing small cell carcinoma from other neoplasms.

We conclude that fine-needle aspiration cytology of the lung is an accurate diagnostic tool for the diagnosis of lung malignancies and is an excellent technique for distinguishing small cell carcinoma from other malignant neoplasms. It can be used with confidence to select treatment modalities and to avoid unnecessary surgeries in patients with lung malignancies.