Address for correspondence : Il-Seok Park, MD, Department of Otorhinolaryngology-Head and Neck Surgery, Hallym University College of Medicine, Dongtan Sacred Heart Hospital, 7 Keunjaebong-gil, Hwaseong 445-907, Korea
Tel : +82-31-8086-2670, Fax : +82-31-8086-2681, E-mail : ispark@hallym.or.kr

Introduction

Warthin's tumor is most frequently seen in the parotid gland next to pleomorphic adenoma.1,2,3) On histopathological finding, Warthin's tumor is composed of lymphoid stroma and double layered oncocytic columnar epithelium, and small microscopic foci of inflammation, necrosis, and fibrosis are identified.4,5) The infarcted variant of Warthin's tumor is characterized by replacement of much of the original oncocytic epithelium by metaplastic squamous cells, combined with areas of inflammation, necrosis and fibrosis. The pathogenesis is unknown; however, it is most likely to be vascular in origin. In rare cases, Warthin's tumor accompanies facial nerve palsy6) and overlying skin ulceration,7) like a malignant parotid tumor. To date, only four similar cases of the ulcerating Warthin's tumor have been reported in the literature. It may be caused by inflammatory changes in the adjacent soft tissue after fine needle aspiration biopsy (FNAB) or incisional biopsy.5) The gross finding of the case reported herein was close to the malignant form, but because an FNAB history existed, the possibility of the occurrence of more inflammatory changes was considered. Therefore, as complications such as facial-nerve injury may be caused by extensive surgery, the latter should be avoided.

Case

A 64-year-old man was referred to our hospital for evaluation of an enlarging right parotid mass with overlying skin ulceration. The mass first appeared asymptomatically 4 years ago. Two years prior to his visit to our clinic, the patient underwent FNAB in another clinic and a diagnosis of Warthin's tumor was made. However, he did not undergo surgery at the time of the first diagnosis, which resulted in abrupt growth of tumor and overlying skin necrosis, just 4 months prior to his admission to our clinic. He presented to us with pain and bleeding from the mass, which was initiated after the skin ulceration overlying the mass was identified. Physical examination revealed a hard, fixed, ulceroproliferative lesion measuring approximately 5×6 cm and thinning with necrosis of the adjacent skin on the right side of the cheek (Fig. 1). There was neither cervical lymphadenopathy, nor facial nerve palsy. Computed tomography (CT) showed an ill demarcated mass with heterogenous enhancement in the superficial lobe of the right parotid gland (Fig. 2). Magnetic resonance imaging (MRI) revealed a mass with low signal intensity on a T1-weighted image and high signal intensity on a T2-weighted image (Fig. 3). Punch biopsy was performed, and Warthin's tumor with inflammation and necrosis was reported. The patient underwent superficial parotidectomy with an advanced flap for the skin defect. During the operation, the tumor was easily separated from the adjacent tissues, and no recurrence was found at follow-up after 24 months.
Macroscopically, the tumor showed an exophytic and lobulated contour. Microscopically, the tumor consisted of lymphoid stroma with a germinal center, peripheral metaplastic squamous epithelium, instead of double layered oncocytic columnar epithelium, dense fibrosis, and extensive necrosis (Fig. 4).

Discussion

Warthin's tumor is a benign salivary gland tumor that occurs preferentially in the parotid gland. It has a slight male predominance. The pathogenesis of Warthin's tumor is uncertain. The most commonly proposed pathogenesis of Warthin's tumor is that the tumor arises from intraparotid lymph nodes.8) Microscopically, the tumor consists of a variable components of lymphoid stroma and epithelial component.1,4) Warthin's tumor with skin ulceration is extremely rare.7,8,9) Until now, four cases have been reported in the literature. Overlying skin involvement of salivary gland tumor usually imply the possibility of malignancy.9) The clinicopathological characteristics of this newly diagnosed entity are important for differential diagnosis from malignancy associated Warthin's tumor.10)
Otolaryngologists need to pay attention to Warthin's tumor, considering its character of proclivity for inflammation and infarction, which may cause either spontaneously or as a result of FNAB.9) Its pathogenesis is unknown; however, the infraction of Warthin's tumor, which is replacement of the original oncocytic epithelium by metaplastic squamous cells, formation of cholesterol and sarcoid-like granulomas, vascular obliteration, and, finally, infraction develop in the tumor.9) These histopathological changes may occur across the capsule of the tumor into the adjacent soft tissue of parotid gland including skin. However, it is extremely uncommon for them to reach the overlying skin.9) Other factors that arise the possibility of skin ulcer formation include ischemic changes, accidental external skin damage such as shaving, compression the overlying skin, an insect bite, and malnutrition.11) In our case, the inflammatory process crossed the parenchyma of the parotid gland, capsule, soft tissues, and overlying skin. In cases involving a infracted variant of Warthin's tumor, there are no specific symptoms, and diagnosis is made according to histopathology.5) In our case, we speculated that ulceration of Warthin's tumor was caused by transcapsular extension of the inflammation, which had been induced by the previous FNAB. It is impossible to predict the occurrence of such extensive inflammatory changes in the parotid gland after FNAB of a Warthin's tumor.5)
Besides the history of FNAB, neglecting the tumorous lesion, which was not surgically treated for several years after first diagnosis was the common past medical history among the patients, showing the Warthin's tumor with skin ulcera-tion.7) Therefore, when otolaryngologists exam the patient presenting the asymptomatic salivary gland tumor for several years, followed by the history of rapidly growing tumor with skin ulceration, not only the malignancy but also the possibility of Warthin's tumor with skin ulceration should be considered.
Also in our case, the radiologic finding including ill-defined mass lesion with overlying skin involvement is different from the general features of Warthin's tumor, which is smoothly marginated with heterogenous density in CT. When the ill demarcated mass lesion with skin ulceration on radiologic study is first identified, we should consider the inflammatory process related changes of Warthin's tumor besides the malignant lesion.
In conclusion, occurrence of an ulcerating Warthin's tumor is an exceedingly rare condition and should be considered in differential diagnosis of skin invasion by malignant salivary neoplasms. In order to avoid misdiagnosis of malignancy and unnecessarily wider resection, both otolaryngologists and pathologists must be aware of this disease entity and possible histopathologic changes by the previous FNAB.

1. Eveson JW, Cawson RA. Infarcted ('infected') adenolymphomas. A clinicopathological study of 20 cases. Clin Otolaryngol Allied Sci 1989;14(3):205-10.

2. Kim JY, Kim JP, Lee EJ, Woo SH. A case of multifocal multisite Warthin's tumor. Korean J Otorhinolaryngol-Head Neck Surg 2010;53(12):778-80.

3. Lim S, Ryu S, Lee K, Hwang B, Lee EJ, Hong KH, et al. A clinical study of the Warthin's tumor of the salivary gland. Korean J Otorhinolaryngol-Head Neck Surg 2011;54(3):213-6.

4. Stárek I, Skálová A, Tichý T. Histopathologic changes in parotid gland parenchyma after fine needle aspiration biopsy of a Warthin's tumour. A case report. Pathol Res Pract 2002;198(12):829-32.

5. Di Palma S, Simpson RH, Skálová A, Michal M. Metaplastic (infarcted) Warthin's tumour of the parotid gland: a possible consequence of fine needle aspiration biopsy. Histopathology 1999;35(5):432-8.

6. Lesser RW, Spector JG. Facial nerve palsy associated with Warthin's tumor. Arch Otolaryngol 1985;111(8):548-9.

7. Abraham Z, Rozenbaum M, Keren R. Skin ulcer at the blunt apex of a giant Warthin's tumor. J Dermatol 2000;27(8):523-8.

8. Patel B, Mandel L. Warthin's tumor of the parotid salivary gland. A case report. N Y State Dent J 1999;65(8):26-8.

9. Stárek I, Tichý T, Skýpalová P, Skálová A. Ulcerating Warthin's tumour. Acta Otolaryngol 2004;124(6):744-6.

10. Yamada S, Matsuo T, Fujita S, Suyama K, Yamaguchi A, Mizuno A. Mucoepidermoid carcinoma arising in Warthin's tumor of the parotid gland. Pathol Int 2002;52(10):653-6.

11. Sadahira C, Matsuota Y, Numahara T, Miyabe K, Mori N, Kubota Y. A case of ulcerative Warthin's tumor. J Dermatol 2004;31(9):779-81.