Accidental inclusion of viable conjunctival epithelium under intact conjunctiva, may lead to cyst formation. Various transconjunctival ophthalmic procedures are reported to be associated with this complication.123456 Conjunctival inclusion cysts are also reported after penetrating trauma. The probable mechanism by which the cyst grows is by retention of the conjunctival epithelium under intact conjunctiva, followed by secretion of mucus from goblet cell into an epithelial lined cavity. The areas most prone for the development of cysts are 1) at the insertion of the muscles, 2) incision line, 3) fornix and 4) limbus. We herein report an intriguing case of histopathologically confirmed inclusion cyst of the cornea, following filtering surgery. To our knowledge, this is the first report of giant inclusion cyst of the cornea.
A 55 years old lady presented to us with the complaints of discomfort and watering in her left eye, since past 8 months. She noticed a white opacity in the left eye, that was increasing in size since the same time. Treatment history was significant for two surgeries done in the left eye 1) trabeculectomy followed in three months by 2) combined cataract surgery with intra ocularlens implantation and trabeculectomy procedure, 8 years back.
On examination, the right eye was normal. Left eye showed presence of an avascular, pearly white mass in the cornea, at the level of the anterior stroma [Figures 1 and 2]. There was no transparent corneal tissue between the nasal limbus and the mass. There were three blood vessels under the mass in the cornea, which were more visible after the mass was excised. The mass did not stain with fluorescein. An ultrasound biomicroscopy revealed a solid mass lesion of the cornea, in front of intact Bowman's membrane [Figure 3]. There was no light perception in this eye. Intraocular pressure and gonioscopy recorded from the eccentric healthy area of the cornea, were normal. Fundus examination revealed total glaucomatous optic atrophy. Cause of unilateral, burnt out glaucoma in this eye could not be ascertained. However, there was no evidence of previous trauma, herpes viral keratitis or kerato-conjunctivitis sicca.
The surgical excision of the mass was simple. The mass could be peeled off easily with blunt dissection, once a surgical plane was created. The epithelium healed well [Figure 4]. There was no recurrence of the lesion at the end of 24 months.
The histopathology revealed few squamous epithelial cells and submucosal accumulation of acellular, smooth, structureless pale, eosinophilic material. There were no goblet cells in the cyst wall. The material did not stain with Congo-red stain. There was no evidence of fungus, granuloma, atypia or malignancy.
Conjunctival incision and suturing near the limbus may predispose the eye for the development of inclusion cysts. These cysts may disappear spontaneously, but persistent cases require treatment. Treatment can be either with the excision of the cyst or cauterization. These cysts may produce discomfort due to ocular surface irregularity and recurrent inflammation. Histopathological findings are characteristic. An ultrasound examination may reveal a solid lesion due to the high echogenicity of the accumulated material.
Use of antifibrotic agents like Mitomycin C and creating a limbal-based flap may reduce the risk of the cyst formation after filtering surgery. Non traumatic formation of conjunctival cyst by inflammatory infiltrates can also occur with pingueculitis, pterygium, vernal catarrh and pyogenic granuloma. However, this patient had none of these pathologies in the same eye or in the contralateral eye. Mucus plaque keratopathy (filamentary keratitis) is a close differential diagnosis. It can occur following viral keratitis and in dry eye disease. In this patient, there was no evidence of kerato conjunctivitis sicca. The result of careful excision was gratifying.
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