Open Epidermoid Cysts of the Vocal Folds: Our Experience with Four Cases

INTRODUCTION

A glottic cyst is a benign well-encapsulated collection of fluid of varying consistency, typically found lying free in the superficial lamina propria (SLP) underneath the epithelial layer and thus referred to as a subepithelial cyst (SEC).¹ Two types of cysts, mucous retention cyst and epidermoid cyst are found within the Reinke’s space. Mucous retention cysts are often translucent and are lined with cuboidal or columnar epithelium, presumed to arise from obstructed mucus-producing glands.³ Epidermoid cysts contain epithelium or accumulated keratin. They may be congenital in origin (dysembryoplastic theory) or may occur secondary to vocal abuse and phonotrauma (traumatic theory).⁴ An open epidermoid cyst can be seen when an epidermoid cyst spontaneously ruptures and opens into the laryngeal lumen, but still retains some of the accumulated keratin; in this case, the cyst’s outline may be more subtle, and it usually assumes an oval shape with the long axis oriented anteriorly and posteriorly (Fig. 1). An open cyst may also produce a mottled appearance⁵ (Fig. 2A). Ruptured cysts may also generate vocal fold pits or mucosal bridges. According to the theory of Bouchayer and Cornut (1985), a mucosal bridge arises from two apertures in a single epidermoid cyst, superior, and inferior since the mucosal bridge between the two apertures is always thick and hyperkeratotic.⁶ Mucosal bridges may cause dysphonia of varying degrees, especially when associated with other laryngeal lesions such as vocal cysts or sulci (Fig. 2B). They are difficult to detect even on stroboscopy, and their significance and management are fraught with controversy with no real consensus on its optimal management. A type III sulcus refers more to a localized area of depression, also called a focal pit. Hyperkeratosis is common near the deepest aspects of the sac or pocket. Some authors believe that this represents an open epidermal cyst.⁷ Whether this entity of keratin deposition in a sac is a ruptured cyst or an accumulation in a focal pit, remains debatable.

CASE DESCRIPTION

DISCUSSION

Vocal fold cysts are a common cause of dysphonia and are relatively easy to identify on stroboscopic evaluation and mostly require surgical excision. However, significant confusion exists regarding the diagnosis and management of open cysts particularly more so when they are coexisting with other vocal fold lesions such as mucosal bridges and sulci. One hypothesis claims that these lesions are the result of congenital anomalies occurring in the fourth and sixth branchial arch in the course of development of the larynx which could explain the finding that cysts, sulci, and mucosal bridges are seen together, with each of these entities representing a different stage in the evolution of the same congenital entity.⁸

An open cyst can often appear as a keratotic lesion on white light or stroboscopic evaluation/narrow-band imaging (NBI), and the clinical diagnosis is confirmed only after palpation of the lesion under suspension laryngoscopy under general anesthesia. Open cyst is a cyst which has burst into the laryngeal lumen as seen by a point opening in the cyst wall with extrusion of its content into the laryngeal lumen and thus may be differentiated from a focal pit, which is a localized area of depression with no overlying epithelial cover and has accumulated debris within. Mucosal bridges are also best picked up during microlaryngoscopy (MLS). Whenever two linear sulci are observed on stroboscopy or during MLS, a mucosal bridge should be palpated for. Whenever a patient is subjected to MLS, palpation with a blunt elevator is advocated to confirm the presence of a mucosal bridge.¹

Over the last 3 years (January 2015–December 2017), we have operated on 115 cases of vocal fold cysts, of which 4 were diagnosed as open cysts (3.47%). In our series of 4 cases of open cysts, all patients were females and had similar findings of an open cyst found on the left vocal fold with only one patient having bilateral open cysts. The rate of benign vocal fold pathology has been found to be disproportionately higher in females.⁹ This result has been explained based on the higher fundamental frequency and consequently increase in collision trauma.^10,11 In addition, less hyaluronic acid in the SLP of females is another possible cause.¹² We could not find a possible explanation as to the location of all four cysts involving the left vocal fold. All four patients were presented with hoarseness of long-standing duration, probably suggesting its congenital etiology. Stroboscopic picture was suggestive of an open cyst in all four cases, and the findings were confirmed when these patients underwent MLS. Under suspension laryngoscopy, palpation of the vocal fold lesion is imperative. A blunt flap elevator was used in all cases to palpate both the vocal folds, which revealed open cysts, occasionally along with mucosal bridges, focal pits, and sulci on ipsilateral as well as contralateral vocal fold. Concurrent ipsilateral open cyst and mucosal bridge may be a result of variable openings made in two epidermoid cysts of the same vocal fold. Once a clinical diagnosis is made, surgical excision of these lesions poses a challenge. In all the cases, the open cyst was excised along with the entire cyst wall using a laser and sent for histopathological diagnosis. According to the histological classification (Koren classification) proposed by Jacob et al.,¹³ all our cysts fall under type IV: Cysts lined by squamous epithelium with keratinization. The freshened edges were then sutured by 5-0 or 6-0 vicryl. As for the mucosal bridge, there exists a dichotomy of opinion among laryngologists as to the necessity to excise the mucosal bridge or let it be. We prefer its excision when it is thin and epithelial so as to avoid two epithelial surfaces vibrating as separate entities during phonation. However, thick mucosal bridges are best not removed for fear of decreasing the bulk of the vocal fold significantly.¹

In our series of four patients of open cysts, two had concurrent lesions. In the first case, the patient had bilateral complete thin mucosal bridges, which were excised, and the undersurface of the focal pit was made raw. In the second case, the patient had an incomplete mucosal bridge with underlying fibrosis, which was lasered. The most important step in all the cases was suturing of the new epithelial edges, which when sutured together brings the infraglottic epithelium to cover the medial vibrating edge. This ensures a smooth medial vibrating edge for a good postoperative vocal outcome. All patients were advised adequate voice rest after surgery so as to allow complete healing of the vocal folds followed by voice therapy for 2–3 months. The patients had a good vocal outcome 2 months after surgery with decreased vocal fatigue and an increase in the pitch of the voice. There was no voice deterioration in our small series of four cases. Postoperative recovery is found to be slower for vocal fold cysts that are on or near the vocal fold ligament compared to lesions in the subepithelial space.¹⁴ Similarly, the healing postoperatively in cases of open cysts was found to be more gradual than in the case of SECs. In our series, in cases with SEC, it took about 4–6 weeks for complete healing to occur whereas, in a cyst entering the vocal ligament (intraligamentous cysts) as well as open cysts, healing took a long time, taking up to 3–5 months. This was probably due to the larger surface area of the lesion and the use of microsutures to close the defect, which is known to result in an increased collagen concentration of lamina propria, which in turn attributes to vocal fold scarring and stiffness.¹⁵ It is advisable to counsel patients with suspected open vocal fold cysts regarding longer recovery time and intensive voice therapy postoperatively.

CONCLUSION

Over the last 3 years, 3.47% of our vocal fold cysts were diagnosed as open cysts. Out of the four cases, open cysts were found in association with mucosal bridges or sulci in two cases (50%), and hence an accompanying lesion should always be looked and palpated for during surgery. Intraoperatively, after the excision of the cyst wall with its content, the new epithelial edges were sutured to cover the medial vibrating edge. The sutures may slow down the healing process but permit a smooth medial vibrating edge for a good vocal outcome postoperatively. The average improvement of MPT, in our series of patients, was 6 seconds with considerable improvement in the amplitude of the mucosal wave.

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