|Year : 2012 | Volume
| Issue : 1 | Page : 28-29
Epidermal cyst of the bony external auditory canal in an adult
Ihshan Ali, Rauf Ahmad, Irfan Iqbal, Imtiaz Darwesh
Department of Otorhinolaryngology, Head and Neck Surgery, Government Medical College, Srinagar, Kashmir, India
|Date of Web Publication||10-Jul-2012|
Department of Otorhinolaryngology, Head and Neck Surgery, Government Medical College, Srinagar, Kashmir
Source of Support: None, Conflict of Interest: None
To present a rare case of epidermal cyst of the bony external auditory canal (EAC) in an adult. Epidermal cyst of the bony EAC, although very rare, should be kept in the list of differential diagnosis of a skin-lined mass of the EAC. Epidermal cyst is very rare in the EAC. Only two cases of epidermoid cyst arising from the bony EAC are reported previously in English, but both were in pediatric age group. Epidermal cyst in EAC in adult patients may be confused with masses that are commonly seen, and these include osteomas, exostosis, ear polyps, carcinomas, etc. Epidermal cyst should be included in the differential diagnosis of a patient with an ear mass.
Keywords: Epidermal cyst, External auditory canal, Polyp
|How to cite this article:|
Ali I, Ahmad R, Iqbal I, Darwesh I. Epidermal cyst of the bony external auditory canal in an adult. Indian J Otol 2012;18:28-9
| Introduction|| |
Epidermal inclusion cyst refers to those cysts that are the result of the implantation of epidermal elements in the dermis and proliferation of the epidermal cells within a circumscribed space of the dermis.  Epidermal cysts are rare tumors that may occur anywhere in the body. About 7% of them are found in head and neck region. Dermoid cysts can be classified into three histological types: epidermoid cyst (with no dermal annexes in its covering epithelium), dermoid cyst (presence of skin annexes such as sweat gland cells and hair follicles), and teratoid ones (covering containing structures derived from three generative layers).  Epidermal cysts are slowly growing ,elevated, round, firm, intradermal or subcutaneous tumors that cease growing after having reached 1-5 cm in diameter. , The most frequent site involved by epidermal cysts in the head and neck region are neck, cheek, pre-auricular area, and nasal area.  Epidermal cyst is very rare in the external auditory canal (EAC). 
We report one such case of epidermal cyst of bony EAC that presented with fullness and hearing loss.
| Case Report|| |
A 58-year-old male presented with complaints of decreased hearing and fullness in the right ear. These symptoms were gradually increasing in intensity over a period of 2 years. There was no history of pain in the ear or discharge from the ear. There was no history of trauma or surgical procedure in the same ear. On examination, there was a firm, skin-covered, smooth mass filling the EAC [Figure 1]a. It was not tender to touch. The mass was completely occluding the canal; the tympanic membrane was not visualized. Probe could not be passed around the lesion. Left ear was normal. Tuning fork test and pure tone audiometer showed conductive hearing loss in the right ear. Computed tomography scan showed a mass in the EAC; tympanic membrane and the middle ear were normal. There was no erosion of the surrounding bony canal wall [Figure 1]b. The mass was excised under general anesthesia by endaural approach [Figure 1]c. The cyst was excised completely with intact capsule. Canal pack was kept. The cyst was filled with cheesy material.
|Figure 1: (a) Yellowish skin covered mess filling external auditory canal (arrow). (b) CT scan showing soft tissue mass arising from superior wall of ear canal(arrow). There is also a mass of debris collected medial to the cyst (block arrow). (c) endaural incision, cyst filling auditory canal|
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| Discussion|| |
Epidermoid cyst is the most frequent cutaneous cyst of the head and neck.  It is extremely rare for an epidermoid cyst to appear in the bony EAC. Only two cases of epidermoid cyst arising from the bony EAC are reported previously in English,  but both were in the pediatric age group. Epidermal cysts grow slowly and usually do not cause symptoms, but they may become inflamed or secondarily infected, resulting in pain and tenderness.  These cysts appear as a firm, round, elevated, flesh-colored or yellow or white, subcutaneous or intradermal nodule of variable size. A central pore or punctum is an inconsistent finding that may tether the cyst to the skin. , In this case, the patient was an elderly male who presented with complaint of fullness and decreased hearing in the ear, which was caused by the obstruction of the canal by the cyst.
Epidermal cyst in the EAC in adult patients may be confused with masses that are commonly seen. These include osteomas, exostosis, ear polyps, carcinomas, etc.
Epidermal cyst results from proliferation of epidermal cells, which are formed by embryologic aberration or traumatic inclusion. , Diagnosis is made by clinical evaluation, radiological imaging, and histopathological examination of the excised tissue. Computed tomography of the temporal region is done to see the location and extension and involvement of the adjacent sites.  Treatment is by complete excision of the cyst; approach depends upon the size of the cyst, location, and size of the canal.
In summary, we have reported a case of epidermal cyst of the bony EAC, which seems to be only the third case in the literature and the first case of epidermal cyst of bony EAC in an adult patient reported in the literature.
| References|| |
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