Immunohistochemical Characterization of the Ectopic Epithelium Devoid of Goblet Cells From a Posttraumatic Iris Cyst Causing Mucogenic Glaucoma.

PURPOSE

Mucogenic glaucoma is an unusual form of secondary open-angle glaucoma caused by intracameral ectopic mucus-producing epithelium. To date, only 3 cases have been described in detail. Numerous goblet cells in the specimens indicated a possible conjunctival origin. We immunohistochemically characterized the implanted epithelium from an iris cyst responsible for mucogenic glaucoma.

METHODS

A series of immunostaining analyses were performed on a sector-iridectomy specimen derived from an eye with mucogenic glaucoma and a history of limbal penetrating injury. An iris cyst was present in the inferonasal quadrant of the right eye of a 58-year-old man. The anterior chamber was filled with hazy, translucent material, and the chamber angle was gonioscopically open. The cyst was resected due to medically uncontrollable high intraocular pressure.

RESULTS

The ectopic epithelium was mostly positive for CK19, a corneal and conjunctival epithelial marker. Negative staining for MUC5AC, a secretory mucin, and positive staining for MUC1, a membrane-bound mucin, corroborated the absence of goblet cells. Ectopic epithelial cells were abundantly positive for CK15, a limbal basal cell marker, but there was patchy immunostaining of CK13, a conjunctival epithelial marker, and sparse labeling with CK12, a corneal epithelial marker. Immunostaining patterns of CK15, CK13, and CK12 were nearly mutually exclusive.

CONCLUSIONS

The ectopic epithelium of an iris cyst causing mucogenic glaucoma was most likely to originate from limbal basal cells, which showed dual direction of differentiation toward both the conjunctival and corneal epithelia. The membrane-bound mucin may have caused mucogenic glaucoma in the absence of goblet cells.