Developmental Cysts of the Orbit With Mixed Conjunctival and Cutaneous Epithelial Phenotypes.

AIM: To describe the characteristics of patients presenting with congenital orbital cysts containing epithelia of both cutaneous phenotype-that is, epidermis with or without keratin, and at least one dermal structure (sweat gland or pilosebaceous unit)-and conjunctival phenotype (with goblet cells); these cysts with mixed lining are termed "dermo-conjunctival" cysts.

PATIENTS AND METHODS: Review of clinical records for patients having dermo-conjunctival cysts that were treated between 1997 and 2017; patients with cysts of solely conjunctival or solely cutaneous origin were omitted. Data recorded included gender, age at presentation, laterality, orbital location, ophthalmic features, surgical and radiological data, and light microscopic findings.

RESULTS: Of 241 patients with congenital orbital cysts, 22 (9%) contained both cutaneous and conjunctival epithelium; unlike the relatively common congenital cysts lined with solely cutaneous epithelia, these dermo-conjunctival cysts typically occupied the superonasal or nasal quadrants of the orbit (p < 0.000001). Fifteen (68%) of the 22 patients were male, and the group presented at a median age of 22 years (range 8-51 years), with symptoms for a median duration of 5 years (range 1 month-33 years). Fourteen (64%) had noted an orbital mass, 3 (14%) had inflammatory pain, and 1/22 (4%) had reduced acuity. Globe displacement was axial in 7 patients (32%) and nonaxial in 13 (59%), and ocular motility was restricted in 4/22 (18%). Of 17 patients with imaging, 9 (53%) had bone expansion, and the cyst was intimately related to the trochlea in 10 (59%). By definition, all cysts contained conjunctival epithelium with goblet cells: hair shafts were present in 13/22 (59%) specimens, sebaceous units in 18 (82%), sweat glands in 6 (27%), and keratinized epithelium was present in 8 (36%). Fourteen (63%) of cysts had mild chronic inflammation within the cyst wall, and granulomas were present in 8 (36%).

CONCLUSION: Congenital dermo-conjunctival orbital cysts are rare and favor a medial location-this suggesting an origin from sequestered caruncular tissues, the only postseptal source of both dermal and conjunctival structures. Unlike pure cutaneous cysts that typically present as superficial masses in childhood, dermo-conjunctival cysts are often postseptal and present in adults.