A case of giant orbital conjunctival cyst mimicking lymphatic malformation.

A conjunctival inclusion cyst is a colorless or whitish translucent cystic lesion, frequently occurring on the conjunctiva. Here, we describe a patient with a giant conjunctival cyst, mainly existing in the orbit, which clinically resembled lymphatic malformation. A 34-year-old male complained of a subconjunctival mass on his left infero-medial side persisting since childhood. It had gradually enlarged over the 3 months before the initial visit. He had no history of trauma, surgery, or conjunctivitis. The mass was dark red, with superficial dilated blood vessels. Magnetic resonance imaging showed a well-circumscribed mass in the inferior orbit, measuring 12 × 25 mm, which had an internal septum. The lesion was completely resected without rupture of the mass through a transcutaneous approach. Histopathologically, the mass was a cyst composed of columnar epithelium with goblet cells and lymphoid follicles adjacent to the wall. In conclusion, a giant orbital conjunctival cyst and a lymphatic malformation should be differentiated at diagnosis.