Fine-needle aspiration cytology with c-kit immunocytochemical staining in the diagnosis of Warthin's tumor.

OBJECTIVE

Although Warthin's tumor (WT) is one of a few salivary gland tumors that have distinct cytologic findings, it can be confused with malignant tumors at times. We assessed the overall accuracy, unusual features, and diagnostic points of fine-needle aspiration (FNA) of WT.

STUDY

DESIGN

We retrospectively collected histologically confirmed WT from 21 patients and reviewed preoperative FNA slides. Smears were subject to immunocytochemical staining for carcinoembryonic antigen (CEA) and c-kit and compared to metastatic squamous cell carcinoma.

RESULTS

All of the cases were in the parotid gland; the mean size was 3.6 ± 1.2 cm. Of 21 patients, 19 were male (age 59.7 ± 9.4 years) and had a history of smoking. The initial FNA diagnoses were WT (11 patients, 52.4%), benign lesion (7 patients, 33.3%), and malignant neoplasm (3 patients, 14.3%). Only 6 patients (28.6%) showed typical FNA features of WT. The dominant cell types in the smears were macrophages (76.2%), squamous-like cells (66.7%), oncocytes (61.9%), and lymphoid cells (57.1%). Some showed atypical degenerated features, a necrotic background, and inflammatory cells, leading to misdiagnosis. CEA positivity and c-kit positivity in WT were noted in 0 and 75.0% of cases, respectively, whereas metastatic squamous cell carcinoma showed positive rates of 16.7 and 0%, respectively.

CONCLUSION

Awareness of potential sources of misdiagnosis together with combination of c-kit/CEA immunostaining may result in an increased diagnostic rate of WT in FNA.