Unusual giant plunging sublingual epidermoid cyst: A case report and review of literature

Key Clinical Message When treating a painless or asymptomatic mass in the submental or floor of the mouth, sublingual epidermoid cyst should be considered. Despite its irregularity, preventing malignant transformation is essential for a successful outcome. Abstract Dermoid and epidermoid cysts are rarely found in the head and neck region. They account for less than 0.01% of all oral cavity cysts. This is a rare case of a sublingual epidermoid cyst of the oral cavity in a 25‐year‐old male. The patient presented with a painless sublingual swelling for a duration of 1 month. The clinical examination revealed a non‐tender swelling in the sublingual region extending to the submental triangle. Magnetic resonance imaging confirmed a 6.2 × 7.7 × 3.2 cm cystic lesion in the sublingual space. Fine needle aspiration cytology confirmed dermoid cyst contents. Intra‐oral surgical excision under general anesthesia was performed successfully. Histopathological analysis revealed that the cyst wall was lined by stratified squamous epithelium. The presence of a prominent granular layer and keratin flakes confirmed the diagnosis of an epidermoid cyst. Postoperative recovery was good, and no recurrence was observed during follow‐up. This case emphasizes the infrequent and unusual presentation of a case of a giant plunging sublingual epidermoid cyst and promotes awareness and potential studies in the enhancement of patient care in this area.

cyst size, an intra-oral or extra-oral surgical excision is the primary treatment modality. 3Our case emphasizes the rarity of oral epidermoid cysts and highlights successful surgical management with excellent functional and esthetic outcomes.It contributes valuable insights into their clinical presentation, diagnosis, and treatment.

| Case history
A 25-year-old gentleman presented with a complaint of painless swelling over the floor of the mouth for a duration of 1 month which is gradually progressing in size.There was no history of fever, difficulty in chewing, or dysphagia.There was no prior history of any surgery or trauma to the neck.On clinical examination showed a well-circumscribed, non-tender, non-trans-illuminating, bi-digitally palpable, and firm swelling that is present over the floor of the mouth, and extending proximally to the submental triangle (Figure 1A,B).No cervical lymphadenopathy was noted.Systemic examination was unremarkable.

| Methods
T-2 weighted Magnetic resonance imaging (MRI) showed a well-circumscribed oval unilocular midline cystic lesion measuring 6.2 × 7.7 × 3.2 cm (CC × AP × TR) in the sublingual space.The cyst was splaying the genioglossus and mylohyoid muscles to either side.On the left, the lesion extended beyond the confines of sublingual space into the submental triangle through a defect in the mid-third of thinned mylohyoid (Figure 2A,B).Results of fine needle aspiration cytology of cyst revealed pultaceous material that was compatible with contents of dermoid cyst.
Excision of the cyst by an intra-oral approach under general anesthesia was planned.A transverse incision was made with a CO 2 laser scalpel on the mucosa overlying the swelling.Dissection was carried out after creating a submucosal plane around the swelling by traditional method.Bilateral submandibular ducts, their openings, and the lingual nerve were identified and preserved.Vicryl sutures were tied and the sac was opened.Cystic swelling decompression was done to facilitate extirpation of cyst wall revealing thick whitish pultaceous material.The Cyst wall was excised from the floor of the mouth.A saline and betadine wash was followed by the closure of the incision with interrupted 3-0 catgut sutures after achieving hemostasis.(Figure 3A-D) No surgical drain was placed at the site.The post-operative period was uneventful and the patient was discharged on day 2 having reported no complications.

| Conclusion and results
Normal wound healing and no complications were reported during a follow up after 1 week, 6 weeks, and 6 months.The histopathological microscopic examination of the excised cyst (Figure 4), stained using a hematoxylin and eosin stain, revealed a cyst wall with a stratified squamous epithelium lining.It had a prominent granulosa layer.Cyst contained keratin flakes.Focally, the wall showed fibrosis with dense lymphocytic infiltration and capillary proliferation.No skin appendages were noted.The surgical site was healthy and no recurrence was found on follow-up.

F I G U R E 1 (A and B) Clinical
examination showing a wellcircumscribed swelling over the sublingual region and its extension to the submental region.

| DISCUSSION
Sublingual epidermoid cysts are rare and represent approximately 0.01% of oral and maxillofacial cystic lesions. 4,5The sublingual cyst can be histopathologically classified into three types.The first type, epidermoid cysts, is characterized by the presence of an epithelial lining without skin appendages.The second type, dermoid cysts, includes skin appendages, such as hair, follicles, and sebaceous glands within the cystic cavity.Teratoid cysts contain skin appendages and encompass mesodermal elements such as bone, muscle, or respiratory system tissue. 6,7The etiology of these cysts remains uncertain congenital dermoid and epidermoid cysts are believed to result from embryological accidents that occur during early development. 8It is the ectodermal differentiation or the epithelial cells entrapped during midline closure of the branchial arches that are thought to contribute to their formation. 7,8Acquired cysts are known to originate from either traumatic or iatrogenic inclusion of epithelial cells or from the blockage of sebaceous gland ducts. 9Clinical examination revealed a well-circumscribed swelling in the submental triangle, which gradually increased in size.Importantly, the absence of pain, fever, or functional difficulties in chewing or swallowing helped to distinguish this case from other differential diagnoses.Epidermoid cysts typically present as an asymptomatic mass that gradually increases in size. 6However, in some cases, patients may present signs of compression, such as dysphagia, dyspnea, and dysphonia.][12] Accurate diagnosis and optimal preoperative planning are essential for the management of sublingual epidermoid cysts.Imaging modalities, such as ultrasound, CT, and MRI, play a crucial role in determining the location and characteristics of cysts. 10,11Ultrasonography reveals solid and cystic structures within a heterogeneous mass, while CT scans display unilocular masses with thin walls filled with hypoattenuating fluid and fat nodules, presenting a characteristic "sack-of-marbles" appearance. 10,13RI accurately delineated the size, location, and anatomical relationships of the lesion and fine needle aspiration cytology is a safe, economical, and dependable technique that can provide valuable information for the analysis of sublingual lesions. 7This information aided in surgical planning and guided the choice of an intraoral approach for cyst excision. 10,13In this case, the location could be determined by MRI.The cyst extended over the genioglossus and mylohyoid muscles and protruded into the sublingual space on the left side, indicating a plunging epidermoid cyst.
Surgical excision is the preferred treatment modality, with the aim of complete removal of the cyst wall while avoiding rupture to prevent postoperative inflammation. 10,13,14The use of a CO2 laser is an alternative to conventional surgery, enabling precise tissue dissection and minimizing trauma, as was performed in this case. 14currence rates are low after total surgical excision. 10lthough rare, a few cases have reported a malignant transformation to squamous cell carcinoma or basal cell carcinoma. 10,13ublingual plunging epidermoid cysts may pose a diagnostic and therapeutic challenge.Early recognition, aided by clinical examination and imaging techniques such as MRI, is crucial for accurate diagnosis and appropriate management.Surgical excision remains the mainstay of treatment.While the approach depends on size and location of the swelling, meticulous dissection is essential to preserve vital structures and achieve optimal outcomes.

| Review of literature
Our search approach involved crafting a comprehensive search string incorporating relevant keywords and Boolean operators.We aimed to capture literature from both Google Scholar and PubMed databases.Specifically, our search terms encompassed variations related to epidermoid cysts, dermoid cysts, and sublingual cysts, considering their anatomical localization within the oral cavity, including the floor of the mouth, submandibular, and sublingual regions.Additionally, we included terms reflecting diverse aspects of the articles, such as imaging characteristics, case studies, management strategies, pediatric cases, diagnostic approaches, treatment modalities, and literature reviews.The following search strategy was implemented: ("epidermoid cyst" OR "dermoid cyst" OR "sublingual cyst") AND ("floor of the mouth" OR "oral cavity" OR "submandibular" OR "sublingual") AND ("imaging features" OR "case report" OR "management" OR "pediatric" OR "diagnosis" OR "treatment") AND ("literature review" OR "review of cases" OR "report of cases" OR "narrative review").[12][13] Patient demographics revealed a varied age range from infants to 77 years, with predominant being male.Common clinical presentations included slow-growing, painless, non-fluctuant swellings in the floor of the mouth.Less common symptoms encompassed difficulties in speech, swallowing, breathing, occasional tenderness, and asymptomatic cases.Rarely, patients experienced painful non-fluctuant swellings or asymptomatic sublingual swellings.The dimensions of cysts varied across studies, with some reaching sizes up to 10 cm × 8 cm.Surgical excision, primarily via intraoral approaches, was the prevailing management strategy, supplemented by additional procedures such as marsupialization, excision with intact capsule, sublingual gland excision, and intralesional steroid injection.A few cases opted for conservative surgical excision.The overall prognosis was favorable, with a low recurrence rate and most patients experiencing an excellent recovery, marked by a swift postoperative period, as reported in follow-up periods ranging from 6 months to 10 years.

| CONCLUSIONS
Sublingual epidermoid should be kept in mind when dealing with a painless or asymptomatic mass in the floor of the mouth or sub-mental region.Despite its irregularity, maintaining vigilance against malignant transformation is critical.Therefore, early detection, precise diagnosis, and effective intervention are essential for a good functional and esthetic outcome.

F
I G U R E 2 (A and B) T-2 weighted MRI sagittal section and axial view showing the extent of the swelling.F I G U R E 3 (A) Intra-oral approach for excision of the cyst, (B) Transverse incision over the mucosa above the swelling using Co 2 laser, (C) Extirpation of the cyst wall, (D) Excised cyst specimen with pultaceous content.

F
I G U R E 4 (A and B) Histopathological examination of specimen ([A] at 100× magnification and [B] at 200× magnification).Cyst wall lined by stratified squamous epithelium with a prominent granulosa layer.Adnexal structures are absent.T A B L E 1 List of previously published case reports. in the floor of the mouth for 3 months.The swelling had gradually increased in size and was now causing some difficulty with speech.the floor of the mouth for 6 months.The swelling had gradually increased in size and was now causing some difficulty with speech.There was also a 1 cm, mobile, non-tender lymph node in the left cervical chain Painless nonfluctuant swelling in the floor of the mouth that had been present for 6 months.The swelling had gradually increased in size and was now causing some difficulty with speech and swallowing.pain in the throat, difficulty in chewing and swallowing solid food, submental swelling, difficulty in breathing and swallowing, decreased tongue movements and snoring Painful non, painless, non-fluctuant mass in the floor of the mouth for 6 months.swelling of the floor of the mouth and submental region under the tongue and beneath the chin with difficulty in speech and swallowing for 6 months of duration.

25 Female
region(5), pinna(5), sublingual region(1), periorbital(6), suprasternal(6), along the anterior border of sternocleidomastoid (1) and glabella (3), along with an iatrogenic implantation epidermoid cyst in a tracheostomy scar.and deviation of the tongue toward the posterior wall of the oropharynx.Painless non-fluctuant swelling 60-90 (diameter) Surgical excision No Recurrence Saito et al. 31 2012 Swelling of the floor of oral cavity and difficulty in breathing when lying in supine position Painless non