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

Abstract

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.