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.


METHODS
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.


CONCLUSIONS
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.
Department of Pathology, Inje University Sanggye Paik Hospital, Seoul, Republic of Korea. jykimpath@paik.ac.kr
Jung Yeon
JY
Kim
Young Sam
YS
Yoo
Ji Eun
JE
Kwon
Hyun-Jung
HJ
Kim
Kyeongmee
K
Park
D000235:Adenolymphoma / Q000175:diagnosis / Q000378:metabolism* / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D010306:Parotid Gland / Q000378:metabolism* / Q000473:pathology; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods*
D002272:Carcinoembryonic Antigen; D019009:Proto-Oncogene Proteins c-kit