Sir,

We report a case of recurrent giant hidrocystoma that demonstrates the importance of intact excision of these lesions.

Case report

A healthy 46-year-old woman presented with a few months history of painless swelling of the right lower lid. There was no history of impaired vision, diplopia, watering, discharge, or prior trauma. Ophthalmological examination revealed a soft, non-reducible, medial lower-lid swelling with normal overlying skin. The eye was displaced superiorly and laterally. Valsalva test was negative and ocular motility was full. An orbital CT scan showed a large, cystic mass of about 18-mm diameter occupying the infero-nasal orbital quadrant. Surgical excision via conjunctival approach revealed a very thin-walled cystic mass that ruptured during the procedure with the release of clear fluid. The histopathological examination of remnants of cyst wall was inconclusive.

The patient represented 2 years later with a recurrence of the cyst, width 17.5-mm diameter on MRI scan (Figure 1), abutting the globe in the right inferior medial orbit similarly to that seen previously. The cyst was excised intact. Histopathological analysis revealed a benign apocrine hidrocystoma. No further recurrence of the lesion was seen on repeat MRI at 6-months follow-up.

Figure 1
figure 1

Orbital MRI Scan. Arrow shows a giant hidrocystoma (17.5-mm diameter) abutting the eyeball medially in the orbit.

Full size image

Comment

Hidrocystomas are benign sweat-gland tumours that are usually small and are typically found in the head and neck region, especially the eyelid, but other locations including the chest, axilla, palms, and penis have been described.1 Histologically, two types of hidrocystoma, eccrine, and apocrine are recognised reflecting the cells of origin. Spontaneous orbital apocrine hidrocystoma has been reported only once,2 a 10-mm cyst located beneath the orbital roof. Giant hydrocystomas are very unusual, the largest reported by Laktaoui et al3 being a 2-cm eccrine cyst on the eyelid.

The pathophysiology of hidrocystomas is uncertain. It has been hypothesised that sequestration of epithelial cells at the embryonic stage could lead to the condition.4 Bone remodelling or orbital enlargement is often present in long-standing lesions of the orbit but these features were absent in our patient. Traumatic implantation of epithelial cells into deeper tissues, including the orbit,5 has also been described but a history of trauma was absent in our patient.

As this case demonstrates, intact excision may be challenging due to the very thin cyst wall but is necessary to avoid recurrence.