Abstract
Purpose::
To describe 5 patients with hybrid cysts of the eyelid which demonstrated pilar and apocrine differentiation.
Methods::
Clinicopathologic series of 5 cases obtained from review of 1099 cases of hidrocystoma diagnosed at NYEEI from 1990-2006.
Results::
Five patients, aged 38 to 85, presented with eyelid lesions, 4 involving left lower eyelid, and one, the right lateral canthus. Histopathologic evaluation revealed cystic structures, lined predominantly by bi-layered apocrine epithelium, and containing variable amounts of proteinaceous material in the lumen. Foci of keratinized stratified squamous epithelium were observed in 4 out of 5 lesions. Prominent intercellular bridges, granular cell layer formation, and laminated luminal keratin, consistent with infundibular (follicular) differentiation, were present in all 4 of these cysts. One lesion had an additional focus of stratified squamous epithelium without prominent intercellular bridges or granular cell layer. Homogenous eosinophilic keratin material was present in the lumen, suggestive of trichilemmal differentiation. One cyst was lined entirely by apocrine epithelium, but contained both laminated and compact luminal keratin. Continuity with the hair follicle was observed in 3 out of 5 lesions.Immunohistochemical evaluation revealed diffuse strong immunoreactivity of the apocrine epithelium, superficial stratified squamous epithelium, and keratin material to antibodies for CEA and high molecular weight keratin in all 5 lesions. Three out of 4 cysts lined by hybrid epithelium displayed weak focal immunoreactivity to low molecular weight keratin, while the cyst lined entirely by apocrine epithelium showed moderate diffuse immunoreactivity. In cysts with hybrid epithelium, S-100 immunoreactivity was observed only in dendritic cells within the foci of stratified squamous differentiation. Weak focal immunoreactivity to GCDFP-15 was present in the lining of 2 cystic lesions.
Conclusions::
Hybrid cysts are rare lesions that arise from various portions of a hair follicle, most containing a combination of infundibular and trichilemmal epithelia. Cysts lined by apocrine and pilar epithelia are much less frequent. Only one such lesion, to our knowledge, has been described in the eyelid skin. It is likely, however, that these cysts are more common than the literature review would lead one to suspect. Anatomical contiguity of the infundibular, isthmus, sebaceous, and apocrine ductal segments of the hair follicle makes the presence of various epithelia within the lining of a cyst not an unexpected finding.
Keywords: tumors • eyelid • pathology: human