Presenting features for developmental cysts of the orbit

To evaluate the clinical features of developmental cysts of the orbit.

Retrospective study of patients who had excision of cysts between 1992 and 2020.

Three hundred and 58 patients (189 male; 53%) with orbital developmental cysts were identified, all being unilateral. Age at surgery varied from birth to 77 years (mean 17, median 18 years) and the average symptom duration was 5 years (median 18 months; range 1 day-50 years). The commonest presenting features were a peribulbar lump or upper lid swelling, followed by proptosis, pain, diplopia and reduced vision. Most patients (82%) had a palpable mass, with epidermoids, sebaceous dermoids and keratinised dermoids commonly affecting the superotemporal quadrant, and conjunctiva-containing cysts usually being biased to a medial location. Cysts were lined by keratinised epithelium with dermal structures (224/358; 63%), non-keratinised epithelium with dermal structures (69/358; 19%), epidermis without identifiable dermal structures (19/358 'epidermoids'; 5%), conjunctiva (12/358; 3%), respiratory epithelium (4/358; 1%), or mixed dermal and conjunctival epithelia (30/358 'dermo-conjunctival' cysts; 8%). Overall, two-thirds (242/358; 66%) had histological evidence of chronic intramural inflammation, and a half of cysts showed granuloma formation (178/358 cysts). Chronic inflammation was less common with conjunctival cysts (54%, 7/12 patients) and none showed granuloma formation.

Developmental cysts of the orbit vary from the relatively common dermoid cysts to the extremely rare respiratory epithelial-lined cysts. Respiratory cysts, being deeper, may present late in life and cysts containing conjunctival epithelium tend to be less inflamed and typically favour the superonasal quadrant.