Purpose: To describe 2 types of previously unrecognized dermal keratinous cysts of the eyelids-2 single sebaceous duct cysts derived from the glands of Zeis and 2 cases of multiple eruptive vellus hair cysts, both types associated with the pilosebaceous apparatus.
Methods: Clinical records and paraffin sections subjected to hematoxylin and eosin and acid-fast staining were critically reviewed from each case, and additional sections were immunoreacted for cytokeratins (CKs) 7, 14, and 17.
Results: Two patients had a slowly enlarging solitary sebaceous duct keratinous cyst at the eyelid margin where the glands of Zeis are located. The squamous cell lining displayed a corrugated squamous membrane manifesting an eosinophilic, refractile, surface cuticle. Either a sebaceous gland or a hair was proximate to the cyst. The squamous lining was CK7, CK14, and CK17. Two other patients developed over 2 and 10 years a different condition consisting of unilateral or bilateral clusters, respectively, of small papules of the upper eyelids. These were lined by keratinizing squamous epithelium without a cuticular membrane. Numerous small vellus hairs along with keratin in the lumens were discovered with acid-fast staining. The epithelium was also CK7, CK14, and CK17.
Conclusions: Histopathologic and immunohistochemical studies can separate these 2 disparate new eyelid entities from the more common keratinous epidermoid cyst of the surface epidermis or the upper hair follicle (CK7, CK14, and CK17). Simple local excision of the anterior lamella of the eyelid is appropriate for the sebaceous duct keratinous cysts of Zeis, but the multiple vellus hair cysts are comparatively refractory to treatment. Both superficial types of cysts are totally unrelated to the deeper Meibomian keratinous cyst, which is not associated with a hair structure and is situated in the tarsus rather than the dermis of the eyelids.