| Abstract|| |
Sublingual dermoids are the rarest forms of craniofacial dermoids mostly seen in young individuals. Excision of large and deep submental dermoid is generally done via extraoral approach scarring the most prominent part of the face, which can lead to post operative scar hypertrophy and hyperpigmentation especially in non-Caucasian races. Presence of such scars leads to adverse psychological effects in young individuals. Excision via intraoral route, although technically demanding, can be simplified using basic principles of plastic surgery leading to optimal aesthetic outcome with least downtime. We excised a large sublingual dermoid extending deep to the mylohyoid muscle through intraoral approach with excellent cosmetic results. Clinicians dealing with such lesions should keep these principals in their armamentarium when dealing with this rare subset of cases.
Keywords: Dermoid, intraoral, sublingual
|How to cite this article:|
Bhatnagar A, Verma VK, Patel PK. Intraoral excision of large submental dermoid. Indian J Dent Res 2013;24:765-7
Dermoid cysts are manifestation of buried dermal elements. Floor of mouth dermoid constitute only around 1.6-6% of all the dermoids.  The age group affected is usually second to third decade.  In floor of mouth it needs to be differentiated from other commonly found swellings in this location such as ranula, ectopic thyroid, salivary gland tumors and infectious swellings.
The clinical importance of recognizing these lesions as distinct clinical entities lies in the fact that even deep seated dermoids may be easily and optimally treated with surgical excision via intraoral route without any resultant morbidity. Single stage intraoral surgical excision was done in one patient with a large submental dermoid.
| Case Report|| |
A 26-year-old, male presented to us with a floor of mouth soft-tissue lesion for 5 years with complaints of difficulty in swallowing of food and a feeling of globus in the mouth. Examination revealed a large cystic, painless lesion in the floor of mouth pushing the tongue cranially and producing a bulge in the submental region without cervical lymphadenopathy [Figure 1].
Doppler revealed cystic swelling with heterogeneous areas and absence of vascular flow. Magnetic resonance image (MRI) showed a well-defined lesion of 6.0 × 4.1 × 2.8 cm deep to the muscles displacing the oral tongue postero-superiorly [Figure 2]. The lesion was diagnosed as a median geniohyoid (submental) dermoid.
The swelling was excised intraorally under GA. Initially we applied two para-median tongue stitches with 2-0 silk. A large transverse incision was planned in the floor of the mouth, extending between the either premolars over the most prominent part of the swelling. Some mucosal tissue was left on the gingival side in the gingivobuccal sulcus to facilitate water tight closure after excision. Submandibular gland duct was identified before incising. Incision line was infiltrated with diluted xylocaine adrenalin solution. We waited for at least 5 min after infiltration and then gave the incision. Meticulous hemostasis was maintained using bipolar cautery. The muscle was split in the direction of the fibers using sharp dissecting scissors. Once capsule was reached, blunt dissection was done to free the capsule [Figure 3]. The tongue suture was used as traction sutures to achieve good plane of dissection right through the procedure. Complete enucleation was done [Figure 4]. Split muscle and residual cavity was closed over a suction drain. Watertight mucosal closure was done using mattress sutures. Post-operatively clear fluids were started on second post-operative day when suction drain was removed. Semisolid soft diet with meticulous oral hygiene was continued for 2 weeks.
|Figure 3: Capsule exposed after muscle splitting; tongue stitch in place|
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|Figure 4: Complete intraoral excision with intact capsule with histopathology|
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On histopathological examination, it was found to be dermoid cyst.
Microscopic sections showed a cyst lined by keratinised stratified squamous epithelium. The wall showed fibrocollagenous tissue with congested blood vessels, scattered foamy histiocytes and a mononuclear inflammatory cell infiltrate. Sebaceous glands were present in the wall. The cavity was filled with keratin flakes. Foreign body giant cells reaction against the keratin were also seen with no evidence of granulomatous pathology or malignancy [Figure 4].
| Discussion|| |
Dermoids are cystic lesions, lined by keratinizing squamous epithelium and contain skin adnexa such as hair follicle and sebaceous glands.
Head and neck dermoids account for only up to 6.0% of all the dermoids commonly involving the lateral third of the eyebrow area. , New and Erich found only 24 floor of mouth dermoids (1.6%) in their series of 1500 cases with vast majority located in midline (sublingual 53% and submental 26%). 16% involve more than one of the three anatomic spaces of the floor of the mouth (submental, sublingual and submandibular) and up to 6% are located only in the submandibular space and clinically present as lateral neck cysts. ,
Meyer classified the floor of mouth dermoids into three categories based on histological findings.  In relation to mylohyoid muscle it can be differentiated into supra or infra myelohyoid cysts.  Regarding development most widely accepted is that it results from entrapment of ectodermal tissue from first and second branchial arches during fetal development.  There is no sex predilection and commonly presents in the second to third decade. 
The differential diagnoses are Ranula, unilateral or bilateral blockage of Wharton's ducts, thyroglossal duct cyst, cystic hygroma, branchial cleft cysts, acute infection or cellulites of the floor of the mouth, infections of submaxillary and sublingual glands, benign and malignant tumors of the floor of the mouth and adjacent salivary glands.
Fine needle aspiration of the cyst is a cost effective, safe and reliable tool in the diagnosis of dermoid cyst. Sonography differentiates between solid or cystic nature of lesion. MRI is useful in assessing the extent, nature and exact location of the lesion in relation to the surrounding structures.
Excision of the cyst is the definitive treatment. Intraoral approach gives a better cosmetic and functional result. Well-formed capsule helps in easy removal.
We feel that even deep seated and large cysts can be easily excised via intraoral route. Modifications helped us in this procedure. The first step of taking two paramedian tongue stitches with 2-0 silk sutures not only helps in tongue retraction increasing the operating space but also helps in providing traction and counter traction during tumor removal. The use of tongue sutures reduces the need of multiple intraoral retractors thus increasing the intraoral operating space [Figure 3] and [Figure 4]. The large transverse incision extending between the either premolars helps in the identification of the capsule and prevents capsular injury. Care is always taken to identify and protect the submandibular gland duct prior to incision and to place the incision away from the duct opening. Infiltration of incision line with diluted xylocaine adrenalin solution and waiting for at least 5 min helps reduce bleeding and provides post-operative analgesia. Meticulous hemostasis using bipolar cautery helps in accurate identification of tissue planes. Some tissue should be left on the gingival side at the time of initial incision, which helps in water tight closure after excision. Splitting of muscle in the direction of the fibers prevents bleeding, reduces post-operative edema and allows early recovery. The tongue suture is used as traction sutures to achieve good plane of dissection during capsular dissection. After complete enucleation, closure over a suction drain prevents hematoma. Watertight mucosal closure using mattress sutures provides early post-operative recovery. Semisolid soft diet with meticulous oral hygiene helps in good wound healing.
Extraoral approach is needed only in few cases when the intraoral approach is complicated  . The extraoral approach is used for very large dermoid cysts affecting the submandibular and submental spaces and in cases of infection that could compromise the patient's airway. , Surgery is generally without any complication and prognosis is good. Recurrence can occur if the capsule is incompletely removed.
| Conclusion|| |
Although rare in the floor of mouth, dermoid cyst should still be kept in mind as differential diagnosis. Surgical excision via intraoral approach is definitive treatment with good prognosis and very low chances of recurrence even in deep seated submental lesions.
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Department of Plastic Surgery, Sanjay Gandhi Post Graduate Institute of Medical Sciences (SGPGIMS), Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4]