Dermoid cyst simulating mucocele of lacrimal sac: A case report

INTRODUCTION

A dermoid cyst in the orbit is a choristoma (clump of normal tissue in an atypical location). It results from the migration of ectoderm to a hypodermic location along embryonic lines of closure.^[1] The size of the cyst increases gradually due to production of sebaceous and sweat glands inside the lesion.^[2] Orbital dermoid cyst usually present with a non-tender swelling located superiorly, either temporal or nasal.^[1] Superficial orbital dermoid cysts lying near the nasolacrimal passage are rare.^[3] Microscopically, dermoid cysts are lined by a stratified squamous keratinizing epithelium.^[4]

CASE REPORT

A 31-years-old Indian female reported with painless swelling medial to the medial canthus of the right eye which was gradually enlarging in size for the past 2 years as shown in [Figure 1]. It was also associated with watering of the right eye. The mass was firm in consistency measuring about 10 × 5 mm, not adherent to skin, and no tenderness was observed with regurgitation of pus on pressing the lacrimal sac area negative.

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Figure 1:

Pre-operative picture showing the swelling medial to medial canthus.

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Suspecting it to be mucocele of the lacrimal sac, syringing of the lacrimal passage was performed and it turned out to be patent.

On CT-scan, a mass was observed in the lacrimal sac area with no intra-orbital or intracranial extension as shown in [Figure 2]. All the hematological tests were within normal limit.

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Figure 2:

(a) CT-Scan (Axial Cut) – Arrow showing the mass, (b) CT-Scan (Sagittal Cut) – Arrow showing the mass.

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The mass of 5 mm × 8 mm size was excised en masse through an incision of DCR approach under local anesthesia. After giving a curvilinear incision, 3 mm medial to the medial canthus, the orbicularis muscle fibers were separated followed by appearance of the mass as shown in [Figure 3a]. The mass was separated from the surrounding connective tissues taking care not to rupture it. The mass was excised in toto as shown in [Figure 3b] and specimen was sent for histopathological examination.

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Figure 3:

(a) Operative pictures – mass excised en masse, (b) Excised gross specimen.

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Intra-operative lacrimal passage syringing was done and it was found to be freely patent.

Histopathology report revealed stratified squamous epithelial lining with sebaceous glands and it was diagnosed to be a dermoid cyst as shown in [Figure 4].

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Figure 4:

HPE Picture: Side arrow – Sebaceous gland, Down arrow – Squamous epithelium.

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In the immediate post-operative follow-up and on follow-up till 6-month post-operative period, there is no evidence of recurrence with good cosmesis as shown in [Figure 5]. There is also no complain of watering of eye and the nasolacrimal duct is patent on syringing.

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Figure 5:

Post-operative day 14.

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DISCUSSION

The authors report a case of superficial orbital dermoid cyst present close to the lacrimal sac. Watering which was associated in this case is thought to be because of the compression of the lacrimal drainage system by the dermoid. There are very few reports of dermoid cysts associated with involvement of lacrimal passages; to name a few are: Hurwitz et al.,^[5] Kim et al.,^[6] Leuder,^[7] and Tengku-Fatishah et al.^[3]

Complete excision of the dermoid cyst is very important because if a dermoid cyst is partially removed, recurrence may occur. It could also result in complications like inflammation and abscess formation, which may mimic acute dacryocystitis or lacrimal abscess. Residual dermoid tissue may get inflamed leading to orbitocutaneous fistula.^[8,9]

CONCLUSION

Dermoid cyst should also be kept as one of the differential diagnosis in those cases presenting with swelling in the inferonasal part of orbit or in the lower eyelid. Presenting symptoms may mimic a case of mucocele of lacrimal sac in those cases presenting with swelling in the medial canthal area with watering of eye as it was seen in this case. Dermoid cysts have a good prognosis if it is excised completely.