Complex Intratarsal Cyst with a Mixed Ciliated Respiratory-Type and Squamous Epithelial Lining.

A 55-year-old woman developed a painless, non-ulcerated left upper eyelid swelling over 6 months. Examination disclosed a fluctuant mass that permitted movement of the eyelid skin over the lesion. A full-thickness eyelid resection contained a well-encapsulated cyst with milky contents that was predominantly located in the tarsus. The cyst's lining was partially composed of segments of ciliated respiratory-type and non-keratinizing squamous epithelia. Immunohistochemical evaluation with cytokeratins 17, 18, and 19 confirmed the staining pattern of a respiratory-type epithelial cell (whether or not cilia were present in the non-squamous epithelial zones). In the squamous region, entirely different cytokeratin results were obtained vis-a-vis the non-squamous regions of the lining. The current lesion is interpreted as congenital and representing an in situ persistence of embryonic ciliated glandular epithelium that normally exists only transitorily. A more remote possibility is that the lesion was the result of ectopic epithelial cells displaced from an adjacent sinus. A recurrence has not developed during 6 months of follow-up.