Cystic Tonsillar Tumor – Epidermoid Cyst at Palatine Tonsil

Tun-Yen Hsu1, Chuen-Chien Yang1, Yaw-Chang Huang1, Chien-Chung Wang1,

Yu-Chen Shih2, Chih-Chun Wang1

From the 1Department of Otolaryngology, E-Da Hospital, I-Shou University, Kaohsiung, Taiwan, and 2Department of Otolaryngology, E-Da Cancer Hospital, I-Shou University, Kaohsiung, Taiwan.Received: November 22, 2016 Accepted: June 21, 2017Address reprint request and correspondence to: Chih-Chun Wang, Department of Otolaryngology, E-Da Hospital/I-Shou University, Kaohsiung City 82445, Taiwan.Tel: +886-7-6150011 ext. 2973, Fax: +886-7-615-5352, E-mail: ccw5969@yahoo.com.tw

Case Report

Epidermoid cyst is a common cystic lesion with simple squamous epithelial lining. It is often found in the subcutaneous area throughout the body. However, it is seldom found in the deeper region beneath the skin, and is relatively uncommon in head and neck. A 20-year-old man presented with lumping sensation over the throat for several weeks. Local examination revealed a cystic tumor over the right palatine tonsil. Tonsillectomy was performed for both diagnostic and therapeutic purposes. The diagnosis of epidermoid cyst was confirmed by histopathological studies. Epidermoid cyst should be included in the differential diagnosis of cystic tonsillar tumor.

Key words: epidermoid cyst, palatine tonsil, tonsillectomy

Introduction

Epidermoid cyst is a common subcutane-ous cystic lesion with simple squamous

epithelial lining. However, it is seldom found deep beneath the skin and is relatively uncom-mon in the head and neck. Oral cysts are rare. It may be asymptomatic or symptomatic due to mass effect or secondary inflammation/infec-tion. We report a 20-year-old man with sore throat and globus sensation for several weeks.

Local examination revealed a cystic tumor over the right palatine tonsil. Tonsillectomy was performed for both diagnostic and therapeutic purposes and the diagnosis of epidermoid cyst was confirmed histologically.

A man in his 20s presented with pain and globus sensation for several weeks. His medi-cal history was unremarkable, and he had no specific history of tonsillitis. Local examina-

Case Report

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Discussion

tion revealed a yellowish smooth-surfaced cystic mass of size approximately 2 cm over the upper pole of the right palatine tonsil with-out distortion of the surrounding tissue. There were no palpable neck masses or other find-ings on head and neck examination. Contrast-enhanced computed tomographic (CT) imag-ing for head and neck revealed a mixed-density focal protruding nodule over the right pala-tine tonsil (Fig. 1). Tonsillectomy was then performed for diagnostic and therapeutic purposes after having obtained the patient’s informed consent. Pathological examination of the surgical specimen revealed a well-defined

Fig. 1 Contrast-enhanced head and neck computed tomography showing a mixed-density focal protruding nodule over the right palatine tonsil (white arrow).

Fig. 2 A yellowish smooth-surfaced cystic mass (white arrow) over the upper pole of the right palatine tonsil.

Fig. 3 Low magnification microscopic examination (H & E, × 100) showing a cyst lined with keratinizing stratified squamous epithelium (white arrow), surrounded by lymphoid tissue (white triangle), and the cystic space being filled with eosinophilic materials (white star).

Fig. 4 High magnification microscopy (H & E, × 400) demonstrating aggregates of foamy histiocytes in the epithelial and subepithelial areas (white arrow).

submucosal cystic lesion (20 × 15 mm) (Fig. 2) surrounded by lymphoid tissue and lined with keratinizing stratified squamous epithelium with cystic space being filled with homogenous eosinophilic materials, which were intermixed with numerous cleft spaces (Fig. 3). There were foci of aggregates of foamy histiocytes in the epithelial and sub-epithelial areas (Fig. 4). The diagnosis of epidermoid cyst was confirmed by histopathological studies.

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Epidermoid cyst is a common cystic lesion with simple squamous epithelium lining. Histologically, epidermoid cyst, dermoid cyst, and teratoid cyst are three distinct lesions with overlapping features. Epidermoid and dermoid cysts have similar histologic appearance except that the latter has dermal appendages including hair, hair follicles, sebaceous and sweat glands, whereas the former does not. A teratoid cyst differs from epidermoid cyst in that the former contains tissues of ectodermal, endodermal, and mesodermal layers.1 Among these three cystic lesions, epidermoid cyst is the most common to be found in the head and neck area, followed by dermoid cyst.2 Epidermoid cyst and dermoid cyst can be found in any part of our body, with about 7% occurring in the head and neck region.2 Specifically, about 1.6% of epidermoid cyst and dermoid cyst occur intra-orally.2 Epidermoid cyst and dermoid cyst constitute only 0.01% of all the oral cysts.3

The formation of epidermoid cyst or dermoid cyst might be caused by congenital entrapment of epithelial components during development or acquired implantation during trauma or inflammation.1,4

If epidermoid cyst or dermoid cyst is located in the neck, they should be differenti-ated from ranula, thyroglossal duct cyst, bran-chial cleft cyst, cystic hygroma (lymphangi-oma), cervical thymic cyst, and cervical bron-chogenic cyst.5 However, cystic lesion over the palatine tonsil is seldom reported. Until 2016, only two cases of epidermoid cyst on pala-tine tonsil were reported in the English litera-ture.6,7,8 In contrast to the need for pathologi-cal sectioning to establish the diagnosis in the previous two cases, the epidermoid cyst in our report could be easily seen on the surface of tonsil during physical examination.

Several other kinds of cystic lesions such as lymphoepitheial cyst or branchial cyst on the palatine tonsil have also been reported.9,10 These cystic lesions can only be differentiated under microscopy.

Imaging studies can provide some diag-nostic information about epidermoid cyst and dermoid cyst. Ultrasonography can be used to evaluate superficial lesions. They tend to have an “pseudosolid” appearance with posterior acoustic enhancement indicat-ing a cystic lesion. On CT scan, epidermoid cyst and/or dermoid cyst should appear as a well-circumscribed, low-density, unilocular mass. Typically, epidermoid cyst is predomi-nantly fluid-attenuated while fatty contents are pathognomonic for dermoid cyst. On magnetic resonance imaging, either on T1WI or T2WI, a more complex and/or heterogeneous hyper-intense signal is suggestive of a dermoid cyst, while the signal intensity typically shows a uniform increase for an epidermoid cyst. Due to its fat content, fat suppression T1 signal may be low for dermoid cyst.5

Surgical excision is the treatment of choice for an epidermoid cyst. Fine needle aspiration cytology can provide diagnostic evidence prior to surgery. Tonsillectomy is sufficient for therapeutic as well as diagnostic purposes.4

References

1. Meyer I: Dermoid cysts (dermoids) of the f loor of the mouth. Oral Surg Oral Med Oral Pathol 1955;8:1149-64.

2. New GB, Erich JB: Dermoid cysts of the head and neck. Surg Gynecol Obstet 1937;65:48-55.

3. Rajayogeswaran V, Eveson JW: Epidermoid cyst of the buccal mucosa. Oral Surg Oral Med Oral Pathol 1989;67:181-4.

4. Dutta M, Saha J, Biswas G, et al: Epidermoid cysts in head and neck: our experiences, with review of literature. Indian J Otolaryngol Head Neck Surg 2013;65(Suppl 1):14-21.

5. Gaddikeri S, Vattoth S, Gaddikeri RS, et al: Congenital cystic neck masses: embryology and imaging appearances, with clinicopathological correlation. Curr Probl Diagn Radiol 2014;43:55-67.

6. Kelson WH: Microscopical section of cyst of tonsil. Proc R Soc Med 1911;4:118.

7. Swarnagowri BN, Suba G, Nitya P: Epidermal inclusion cyst in palatine tonsil: a case report. Sch J Med Case Rep 2014;2:83-4.

8. Erol K, Erkan KM, Tolga D, et al: Epidermoid cyst localized in the palatine tonsil. J Oral Maxillofac

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Pathol 2013;17:148.9. Choi J, Kim K, Kim B: Lymphoepithelial cyst of

the palatine tonsil. Ear Nose Throat J 2010;89: 584-5.

10. Doğan M, Erkoç MF, Yüce S, et al: A common disease but rare presentation: branchial cyst located on tonsil. Wien Klin Wochenschr 2015;127:17-8.

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