Most cysts of the eyelid are diagnosed as epidermal inclusion cysts, dermoid cysts, pilar/sebaceous cysts or as a chalazion. The diagnosis of epidermal cyst of the tarsal plate is not made very often. This differential should be kept in mind while operating on a cyst of the upper eyelid. A definitive diagnosis depends upon a histopathologic examination, and an en bloc excision with tarsectomy, including the base of the cyst, is the definitive treatment.
A 35-year-old male patient presented with a swelling of the right upper eyelid of 10 years’ duration. The swelling which was initially the size of a peanut started increasing in size since the last 1 year, causing drooping of the upper eyelid. There was no associated pain or redness. There was no history of ocular trauma, previous surgery or any systemic illness. On examination, there was a mechanical ptosis with zero vertical interpalpebral fissure height and zero levator function. The lid showed a large round swelling of 2 cm in diameter [Fig. 1]. On palpation, the tumor was well defined, cystic but firm, and free from skin and bony margins. There were no signs of inflammation and the overlying skin appeared normal. On retraction of the upper eyelid, only 2 mm of the lower cornea was seen which appeared normal [Fig. 2]. The left eye examination was normal. Computed tomography (CT) scan of the right orbit did not reveal any bony attachments on bone and soft tissue window. There were no cysts elsewhere like on face, neck and trunk, and rest of the systemic examination was also normal. The patient was posted for excisional biopsy. A horizontal skin incision was made, inferior to the lid crease. Subcutaneous tissue was separated from the center toward periphery. Careful superior and inferior separation of the cyst from subcutaneous tissue was done [Fig. 3]. Inferiorly, the cyst had reached the lid margin as the hair follicles were visible during dissection. As the dissection proceeded posteriorly, the cyst was found to be attached to the tarsal plate. Hence, a 3–4 mm tarsectomy was done to remove the cyst in toto [Fig. 4]. The tarsoconjunctival suturing was done with 8-0 Vicryl. Excess skin was excised and skin was sutured with interrupted sutures using Proline. The patient was started on oral antibiotics and anti-inflammatory drugs. There was lid edema on the 1st postoperative day. He was started on topical antibiotics. By the 10th postoperative day, the edema had totally subsided, the levator function had returned to normal and there was no ptosis [Fig. 5]. The patient has shown no recurrence in the follow-up period of 5 months and has a best corrected vision of 20/30 post surgery. Histopathology reports showed, on gross appearance, a round to oval 2.5 × 2 × 2 cm cystic, grayish-brown mass. Microscopy revealed a cyst lined by stratified squamous epithelium devoid of keratohyaline granules. The cyst lumen contained string-like keratin [Figs. 6 and 7]. The cyst wall was composed of bland collagenous tissue devoid of inflammation. Part of the tarsal plate and the underlying conjunctiva was attached to the cyst wall. The histopathologic features were consistent with epidermal cyst of the tarsal plate.
Cysts of the epidermis are the second most common type of benign periocular cutaneous lesions, accounting for approximately 18% of excised benign lesions. Most of these are epidermal inclusion cysts which are slow growing, elevated, round and smooth, and filled with keratin. Very few cases of epidermal cysts of the tarsal plate have been reported. Vagefi et al. in 2008 discussed various theories of development of epidermoid cysts. Since there is no history of trauma or surgery in our patient, the most likely theory is the sequestration of epidermal rests during the embryonic development of the eyelid, as was the case in Vagefi's report. Lucarelli et al. reported cases of intratarsal epidermal inclusion cysts which were initially diagnosed as chalazions and for which incision and curettage was done. They were ultimately diagnosed as having originated from the tarsus and protruding into the skin. Finally, the base of the cyst with the tarsus had to be excised to prevent recurrence. Hence, incision and curettage or superficial shave biopsies may not give the exact diagnosis in all cases of lid tumors. A full thickness biopsy of the tarsal plate is diagnostic. Jakobiec et al. presented cases of intratarsal cyst of meibomian gland. The average age of patients was 62.5 years. The authors did an immunohistochemical study with the help of which they distinguished it from the epidermal cysts. To avoid lid retraction, 20–24 mm of skin should be left between the brows and the lid margin. The upper eyelid also requires 4 mm of tarsus along the eyelid margin to ensure stability. This allows us to recruit any excess superior tarsus beyond 4 mm into a defect. In more extensive defects of the tarsus, procedures like eyelid sharing procedure, contralateral upper eyelid tarsoconjunctival grafting or tarsoconjunctival substitutes like hard palate mucoperiosteum could be used. In our patient, the tumor size was 2 cm in diameter and the amount of tarsus that was sacrificed along with the conjunctiva was about 3–4 mm. Five millimeter skin excision was done and no skin graft was required. The layers of the upper eyelid from anterior to posterior, between the lid margin and the lid crease consist of skin, orbicularis muscle, levator aponuerosis, tarsus and conjunctiva. These layers are held tightly together by fibers of the levator aponuerosis that cross the orbicularis and insert into the dermis. The upper eyelid crease is formed by the most superior of these attachments. Since the incision given was inferior to the attachment of the levator palpebrae superioris to the skin, the lid crease was not compromised and ptosis was nil. Jakobeic et al. have documented the first eyelid epidermoid cyst displaying malignant transformation in a 72-year-old woman. Hence, no matter how benign any eyelid cyst may appear, they all should be sent for histopathologic examination.
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