International Journal of Pediatric Otorhinolaryngology Extra
Volume 3, Issue 1 , Pages 17-19, January 2008

Post-auricular dermoid cyst with intracranial extension—A rare finding

Department of Paediatric Otorhinolaryngology, Temple Street Children's University Hospital, Temple Street, Dublin, Ireland

Received 3 April 2007; received in revised form 20 August 2007; accepted 21 August 2007. published online 16 October 2007.

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Summary 

Dermoid cysts are rare soft tissue tumours which usually present at birth. Intracranial extension is a rare occurrence but has been described in temporal, nasal and scalp lesions. However, to date there has been no report in the literature of a post-auricular dermoid cyst with intracranial extension. We report such a case in a 12-year-old male.

Keywords: Dermoid cyst, Intracranial extension

 

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1. Introduction 

Dermoid cysts are rare, benign soft tissue tumours which generally present at birth. They occur most commonly on the face, scalp or neck. Approximately 7% occur in the head and neck area. Intracranial extension of a dermoid cyst is a rare finding, but has been reported with scalp and nasal dermoid cysts. However, to date there has been no report in the literature of a post-auricular dermoid cyst with intracranial extension. We report such a case in a 12-year-old male.

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2. Case history 

A 12-year-old male child was referred by his general practioner with a left post-auricular swelling. The swelling had been present for approximately 18 months with no recent increase in size. He did not complain of any pain or discharge. He had no significant past medical history. On examination he was noted to have a 2cm×1cm post-auricular cystic lesion which was nontender (Fig. 1). The remainder of his ear, nose and throat exam was normal. Clinically, the lesion was suspected to be a dermoid cyst. An MRI scan (magnetic resonance imaging) was requested to further delineate the lesion. A post-auricular subcutaneous dermoid cyst with intracranial extension to the left cerebellar hemisphere was demonstrated. The intracranial portion measured 0.8cm×1cm (Fig. 2, Fig. 3). He was referred to a paediatric neurosurgeon for an opinion.

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3. Discussion 

A dermoid cyst is a rare benign hamartomatous tumour that is derived from both ectoderm and mesoderm. The tumour is usually covered by a thick dermis like wall and contains multiple sebaceous glands and almost all the skin adnexae. Hairs and large amounts of fatty tissue cover poorly to well-differentiated structures which are derived from the ectoderm. Depending on the location of the dermoid cyst these may include hair follicles, smooth muscle, eccrine and or apocrine glands and occasionally teeth, nails or bone like structures. Dermoid cysts of the skin and subcutaneous tissue occur most commonly on the face, neck or scalp. However, in addition to the skin they can also be intracranial, intraspinal, perispinal and intra-abdominal. These benign neoplasms are usually present at birth particularly dermoid cysts of the face, neck and scalp.

However, the age of presentation can vary widely. Approximately 7% of all dermoid cysts occur in the head and neck region, with the most commonly reported sites being periorbital, nasal, submental and substernal [1], [2]. In 1937, New and Erich classified dermoid cysts into three pathological types—acquired implantation, congenital teratoma and congenital inclusion. Acquired dermoid cysts result from a fragment of skin being traumatically implanted in the deeper layers of skin. Congenital teratomas arise from embryonic germinal epithelium of all three types: ectoderm, endoderm and mesoderm. Thus they typically occur in the ovaries and testes. Congenital inclusion dermoid cysts form along embryonic fusion lines and contain both dermal and epidermal derivatives. Dermoid cysts of the head and neck are believed to be congenital inclusion cysts which are divided into four groups [3]:

•Group 1. Develop in the periorbital region and appear along the naso-optic groove between the maxillary and mandibular process during embryonal closure. The periorbital region is the most commonly reported site for dermoid cysts in the head and neck region and accounted for approximately 49.5% in New & Elrich series [1], [3].

•Group 2. Develop over the dorsum of the nose and are thought to develop during ossification of the frontonasal plate. They represent approximately 8–12.6% of all dermoid cysts [3], [4]. Hair protruding through a punctum is pathognomonic for a nasal dermoid cyst [5]. Intracranial extension of nasal dermoid cysts has been reported, and the tract usually passes through the foramen cecum or cribiform plate to the base of the frontal fossa [4], [5]. In Pyror et al.'s series of 49 patients, 1 of 3 (33%) nasal dermoid cysts extended intracranially [1].

•Group 3. These are found in the submental region, the floor of mouth and the region of fusion of the first and second branchial arches in the midline. These dermoid cysts can impair swallow, speech and the airway if they enlarge. In McAvoy et al.'s series 9% of dermoids were in this region [2], [3].

•Group 4. These cysts are formed at the mid-ventral and mid-dorsal fusion in the suprasternal, thyroidal and suboccipital regions. They are occasionally confused with thyroglossal duct cysts or thyroid neoplasms. Group 4 cysts have been reported to account for 5–15% of congenital inclusion cysts [3]. Pryor et al. had five patients who did not fit into the New and Erich classification. These were classified as ‘head not neck’ category, four occurred on the scalp and one on the forehead [1]. This is similar for our patient whose dermoid cyst was located on the post-auricular scalp and therefore does not fit into the New and Erich classification. Intracranial extension of a post-auricular dermoid cyst has not been previously reported based on available literature. Crawford reported three patients with intracranial extension associated with their midline scalp lesion, an incidence of 2.4%. Intracranial extension was initially suspected on plain skull X-ray. This was confirmed by CT scan and surgery in two cases, CT scan was negative in the third [6]. Pyror et al. series reported two patients with intracranial extension of their dermoid tumour, one nasal dermoid confirmed with CT and MRI imaging, and one ear/temporal bone dermoid cyst which was confirmed with CT imaging [1]. Dermoid cysts with intracranial extension are usually associated with midline lesions and the presence of a sinus, dimple or abnormal hair distribution should also raise the suspicion of intracranial extension [6].

However, this case illustrates that these findings are not always present in dermoid cysts with intracranial extension. In conclusion, it is prudent to perform either an MRI or CT scan in any child suspected of having a dermoid cyst in the head and neck region to assess for intracranial extension particularly were surgical excision is planned.

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References 

  1. Shepherd G, Pryor , Lewis J, Weaver A, Orvidas L. Pediatric dermoid cysts of the head and neck. Otolaryngol. Head Neck Surg. 2005;132(6):938–942
  2. McAvoy JM, Zuckerbraun L. Dermoid cysts of the head and neck in children. Arch. Otolaryngol. 1976;102:529–531
  3. New GB, Erich JB. Dermoid cysts of the head and neck. Surg. Gynaecol. Obstet. 1937;65:48–55
  4. Rahbar R, Shah P, Mulliken JB, et al. The presentation and management of nasal dermoid: a 30 years experience. Arch. Otolaryngol. Head Neck Surg. 2003;129:464–471
  5. Wardinsky TD, Pagon RA, Kropp RJ, et al. Nasal dermoid sinus cysts: association with intracranial extension and multiple malformations. Cleft Palate Craniofac. J. 1991;28:87–95
  6. Crawford R. Dermoid cyst of the scalp: intracranial extension. J. Paed. Surg. 1990;25(3):294–295

PII: S1871-4048(07)00070-6

doi:10.1016/j.pedex.2007.08.006

International Journal of Pediatric Otorhinolaryngology Extra
Volume 3, Issue 1 , Pages 17-19, January 2008

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