Acute presentation of an intraoral dermoid cyst causing airway compromise in a young child

Abstract

A 4-month-old boy presented with a cystic swelling at the floor of the mouth causing acute airway compromise. The only previous history of note, was a tongue tie release at 3 days old. CT scan suggested a dermoid cyst with extensive floor of mouth abscess. He had an excision of the cyst and drainage of the superimposed abscess and made a good recovery. The histology report revealed a dermoid cyst which is a rare diagnosis in a child, particularly within the oral cavity. Early treatment is required to remove these lesions especially when they cause airway compromise or swallowing difficulties. This is the first case to our knowledge which suggests tongue tie release procedures causes a predisposition to the development of dermoid cysts in the oral cavity.

Background

Dermoid cysts are benign developmental cysts which can present anywhere in the body.¹ They are differentiated histologically. Dermoid cysts can be differentiated into three types: epidermoid, true dermoid and teratoid cysts. Epidermoid cysts are lined by epithelium only, whereas dermoid cysts are epithelial lined cavities with variable skin appendages.^1–5 Teratoid cysts have linings which can vary, but always contain derivatives of ectoderm, mesoderm and endoderm.¹

Floor of mouth dermoid cysts are rare, accounting for between 1.6% and 6.5% of all dermoid cysts. They also contribute to 23% and 34% of dermoidal pathology in the head and neck region and comprise only 0.01% of all oral lesions within the paediatric population.⁶, There was a review which reported no cases of paediatric intraoral dermoid cysts over a 22-year- period of study at the Mayo clinic⁶. The highest incidence occurs in the second and third decade of life, with no gender predilection.

Differential diagnoses for oral cavity swellings in children include ranula, dermoid cyst, epidermoid cyst, teratoid cyst, lymphovascular malformation and duplication foregut cysts.⁶ To differentiate between these, imaging such as ultrasound (US), MRI and CT scanning, in addition to histopathology, is crucial.⁶

Floor of mouth dermoid cysts typically present as slow growing, asymptomatic masses, most frequently in the midline, above or below the mylohyoid muscle. A sublingual cyst (52%) usually develops above the muscle, and may cause swelling and tongue displacement. Below the mylohoid, a submental swelling (26%) may manifest as a ‘double chin’ appearance.¹ Complications of dermoids include dysphonia, dysphagia and dyspnoea, with airway compromise when large enough to do so.⁷ Radiologically, these lesions are very difficult to diagnose.

We present a case of a 4-month-old boy who had a floor of mouth swelling which was surgically excised and found to be a dermoid cyst with a superimposed infective abscess.

Case presentation

A 4-month-old boy was transferred from a district general hospital to our centre intubated and ventilated for admission to our paediatric intensive care unit (PICU).

He had no medical history of note apart from a simple tongue tie release at 3 days old. In the preceding 2 weeks before admission, his parents noted an indentation under his chin. Progressively throughout 2 weeks, his tongue became pushed towards his hard palate and his parents noticed apnoeic episodes when he was lying flat. In the week leading up to his admission, his condition deteriorated and he was seen five times in the emergency department. He was having difficulty feeding and parents noticed a fever. He was found to have raised inflammatory markers therefore was investigated for a chest, urine and ear infection as well having a lumbar puncture to rule out meningitis. He was given broad spectrum antibiotics and was advised to avoid lying completely flat.

In the day prior to admission, he had apnoeic episodes while supine and was unable to feed therefore he was admitted. There was large floor of mouth swelling. He had a neck US and was intubated due to airway compromise. It was a difficult intubation, with three attempts before being successful. At this point, he was transferred to our unit and was on the PICU.

Investigations

The neck US he had at the previous hospital was compared with a CT neck with contrast he had at our hospital (figure 1). The CT scan showed an irregular thick walled cystic lesion in the oral cavity which measured 3.5 cm in diameter, with the contents showing fluid attenuation but no calcification (figure 2). The report mentioned that the largest component of the mass occupied the floor of the mouth which extended bilaterally anteriorly into sublingual spaces. He also had non- enlarged lymph nodes in the right anterior cervical chain. The findings suggested an extensive floor of mouth abscess with dermoid cysts/lymphovascular malformation/neoplasm/ranula being less likely.

Figure 1.

Initial ultrasound neck prior to intubation showing large floor of mouth swelling.

Figure 2.

CT neck with contrast showing large irregular thick walled cystic lesions on the floor of the mouth.

Differential diagnosis

After initial examination and assessment, the differential diagnoses were as follows:

• Ranula.

• Dermoid cyst.

• Epidermoid cyst.

• Teratoid cyst.

• Lymphovascular malformation.

Treatment

Therefore due to feeding difficulties and airway compromise, he was operated on as an emergency case, on the emergency operating list. During the operation, before even any incision was made, close examination revealed a small punctum seen at level I, therefore this punctum was excised and the tract followed from level I to the base of the tongue (figure 3). Pus was seen from the abscess and therefore this was washed out. The cyst was seen on the floor of the mouth and was excised centrally through suprahyoid muscles. The right omohyoid was cut to dissect the cyst out and was ultimately repaired. There was no breach in the floor of mouth mucosa. A drain was inserted and remained in for 5 days. The pus was sent to microbiology and the cyst sent for histology (figure 4).

Figure 3.

Intraoperative picture showing the opening of the tract at level 1.

Figure 4.

Histology showing dermoid cyst.

The wound was carefully closed in layers, and the patient transferred back to PICU. There was immediate improvement, the vocal cords could now be visualised significantly better with a laryngoscope.

Histology revealed a dermoid cyst.

Outcome and follow-up

Immediately postoperatively, the child was intubated and ventilated in the PICU for 4 days. He was successfully extubated 5 days after the operation. There were no further breathing difficulties however there were difficulties in oral feeding, therefore to ensure a safe swallow was present, the speech and language therapy team provided their expert input.

The child had a prolonged admission for establishing oral feeding, and then discharged home. He has been seen once since the operation in the outpatient clinic and is doing very well. He now has a safe swallow and is feeding normally via oral route. There are no postoperative complications.

Discussion

This young boy was born at term and had no previous health concerns. However, 3 days after his birth, he had a small procedure for a tongue tie. There were no reported complications. A literature search was undertaken to investigate and ascertain whether tongue-tie surgery predisposes one to a cyst or abscess development. There is no known documented link in the literature in both the paediatric and adult populations. We thus postulate iatrogenic inclusion of epithelial cells following tongue-tie release surgery, predisposing to the development of dermoid cysts.

Due to the very complex anatomy, and vast array of pathological processes which can affect the floor of mouth, diagnosing and managing masses in this specific region can be challenging. Some masses, for example, are unique to this region only, such as submandibular gland pathology or a ranula for example. Uncommon entities such a dermoid cysts can quite easily, often be overlooked. Furthermore, imaging alone may not be able to distinguish between lesions. For example, radiologically it is very difficult to differentiate between a dermoid cyst confined within the sublingual space, and a ranula.^{8 9} This is evidenced by Puricelli et al, who reported the recurrence of a dermoid cyst treated two times by marsupialisation as it was misdiagnosed previously for a ranula.

Differential diagnoses in all of our cases were a ranula or lymphovascular malformation. Ranulas are mucous extravasation cysts originating from sublingual glands. They have an estimated prevalence of 0.2 in 1000, in the paediatric population. Management is variable depending on clinical presentation, specifically the cosmetic and more importantly, symptomatic features. Treatments range from ongoing observation, to aspiration and review, or formal planned surgical excision.¹⁰

Lymphovascular malformations generally develop before a child reaches 2 years of age. The preferred method of treatment is most commonly sclerotherapy, but other treatment options include surgical management.¹¹ Surgical intervention is generally reserved for cases where complications arise such as macroglossia.¹² Therefore, a comprehensive clinical assessment must be undertaken, including taking a pertinent history, clinical examination, clinical imaging and histopathological assessment to prevent diagnostic delay and sequelae of inadequate or incorrect treatment or future complications. In one of our cases, there was unfortunately, a diagnostic delay, the child presented to the emergency department fives times previously and was not admitted for further investigations or referred for clinical imaging prior to the last presentation, where on this occasion he was admitted to hospital.

US imaging is often the primary diagnostic modality of choice. Dermoid cysts appear as unilocular cysts, which are well circumscribed with anechoic, hypoechoic or multiple echogenic regions representing skin appendages.² MRI is considered the gold standard for diagnosing cystic masses as it characterises the anatomy of the floor of the mouth due to its multiplanar imaging capabilities and soft tissue contrast enhancement. Despite this being the case, CT is more readily available and most commonly the go to imaging modality in the UK. The ‘sack of marbles’ sign or intracystic floating corpuscles which may be calcified, is pathognomic for dermoid cysts. They are usually hypodense on CT and, hypointense/hyperintense on T1-weighted MRI and hypointense on T2-weighted MR scans.¹³ In the third case presented, the child had both US and CT, however, as the child presented out of hours to our department, MRI was not available. This may have been useful for the surgeon to further prepare for the operation by delineating the lesion and its surround anatomy and anticipating to optimise surgical planning with regard to removing the tract of the cyst more effectively.

Park et al ⁴ in 2013 reported a case in which a prenatal diagnosis of congenital epidermoid cyst of the oral cavity was made via US. On birth, preparations to secure the child’s airway were made in advance, however, fortunately this was not required. As intraoral dermoid cysts are rare and tend to present later in life, adapting prenatal US scans to screen for lesions may not be effective or indicated.

In conclusion, we describe a rare case of oral dermoid cyst in a neonate associated with an abscess successfully treated by surgical excision. We are the first to suggest a predisposition to a tongue tie procedure and development of floor of mouth dermoid cysts.

Definitive management of dermoid cysts is by formal surgical excision. An intraoral approach is employed for small cysts above the geniohyoid muscle. Those that are below the muscle or very large, require an extra-oral approach.

There is an excellent prognosis following surgical excision and postoperative complications are minimal,⁶ however advice regarding symptoms suggesting recurrence should always be mentioned to families and patients, such as swallowing and breathing difficulties.

Patient’s perspective.

From the patient’s parents: We were deeply concerned throughout our son’s admission and had a very difficult time. We found it most difficult during establishment of the diagnosis as we felt we saw an acute deterioration in our son which was being ignored when we were seen multiple times initially. When he was admitted and immediately intubated, this caused obvious anxiety for us.

Now that he has been treated and discharged, while getting regular follow-up by speech and language therapy as well as the Ear, Nose and Throat team, we are very happy and our son has regained normal development. We are keen for others to learn about our son’s presentation so that this rare cause can be always be considered in the differentials for such a presentation therefore allowing an earlier diagnosis and management plan can be made for others.

Learning points.

• Dermoid cysts remain a rare cause of oral cavity swellings in the neonate.

• Surgical excision remains the definitive management for dermoid cysts in the oral cavity with histological analysis to confirm the diagnosis.

• Prompt intervention is required to prevent airway compromise and feeding difficulties.

• There may be a predisposition to developing dermoid cysts in the oral cavity after tongue tie procedures.

• Early postoperative speech and language therapy allows establishment of oral feeding quicker and thus improving the patients care pathway and holistic journey.