CASE 14445 Published on 11.07.2017

Sublingual dermoid: Rare case report

Section

Head & neck imaging

Case Type

Clinical Cases

Authors

Dr Shailesh Rohit DMRD, DNB, Dr Anjali Singh MD path, Dr Neha Patel MS

SRL Diagnostic,
Sardar Patel Hospital and Heart Institute,
Radiology;
Chikuwadi, Opp. Railway Godown
393001 Ankleshwar, India;
Email:drshailesh2305@gmail.com
Patient

2 years, female

Categories
Area of Interest Head and neck ; Imaging Technique Percutaneous, Fluoroscopy, MR, Ultrasound
Clinical History
A 2-year-old female patient presented with progressively increasing swelling in the submental region since birth (Fig. 1). There was no previous history of trauma or surgery to the Head & Neck region. This swelling appeared more prominent on crying.
Imaging Findings
Ultrasound of the neck shows a 33 x 17 mm well-defined anechoic lesion with multiple intralesional echogenic foci in the submental region extending into the sublingual space. There was no evidence of internal vascularity (Fig. 2).

MRI of the neck shows a well-defined T1 hypointense, T2 and STIR hyperintense lesion with multiple T1 hyperintense foci within the lesion giving a 'sac of marbles' appearance. The T1 hyperintense globules suppress on a fat saturation sequence (Fig. 3 a, b, Fig. 4 a, b).

The findings of a cystic lesion containing fat globules on MRI were suggestive of a dermoid/ epidermoid cyst. Correlation with cytology or histopathological examination was recommended.

The patient underwent surgical excision and a dermoid cyst was diagnosed on histopathological examination by demonstrating orthokeratinised stratified squamous epithelium lining the cyst with sebaceous glands in connective tissue (Fig. 5).
Discussion
Epidermoid/ dermoid cysts of the oral cavity represent less than 0.01% of all oral cavity cysts. The cyst is described as epidermoid when the lining consists solely of epithelium, dermoid when skin adnexa are present and teratoid when other tissues such as muscle, cartilage, or bone are present (1, 2). Although these lesions typically manifest during the second or third decade of life they may present at birth with equal frequency in males and females.

Clinically, dermoid cysts usually present as a painless slow-growing mass in the sublingual, submental or submandibular region [3]. Dermoid cysts of the oral cavity, either sublingual or submental, start in the midline but may extend laterally and inferiorly, attaining a large size before presentation. There may be a sudden increase in their size at the onset of puberty due to greater sebum secretion by sebaceous glands or they may present with secondary cyst infection due to blockage of salivary glands within the cyst or by implantation of oral microbials into the cyst through trauma causing pain, trismus, fever, dysphagia, odynophagia and cervical lymphadenopathy [4]. These patients may also present with difficulty chewing and swallowing if lesions attain a large size.

Ultrasound reveals a cystic mass with intracystic components in the form of calcification and fat globules. However, more detailed anatomical and pathological evaluation is possible with CT or MRI which can be of great help prior to surgery. Multiple intracystic fat globules are seen giving an appearance of a 'sac of marbles' which is the classical sign of a dermoid cyst on US, CT and MRI [5, 6].

Treatment is by enucleation via an intraoral or extraoral approach. An intraoral approach is recommended by most authors for sublingual cysts of small or moderate dimensions (<6cm) above the mylohyoid muscle, whereas an extraoral approach is preferred for larger sublingual cysts (>6cm) [7]. Overall prognosis is excellent and the incidence of recurrence is very low unless the cyst is closely related to the hyoid bone/genial tubercle. Malignant degeneration is said to occur in dermoid cysts with an incidence rate of around 5% in the literature [8].

There is a wide differential for cystic lesions in the floor of the mouth. An understanding of their radiological features, anatomical location and underlying pathology helps establish the final diagnosis.

This case is of interest due to its rare anatomical location and important to consider in the differential diagnosis of a floor of mouth lesion.
Differential Diagnosis List
Sublingual dermoid cyst.
Epidermoid cyst
Ranula
Final Diagnosis
Sublingual dermoid cyst.
Case information
URL: https://www.eurorad.org/case/14445
DOI: 10.1594/EURORAD/CASE.14445
ISSN: 1563-4086