Mucogenic glaucoma in a child.

PURPOSE: We describe a case of secondary open-angle glaucoma due to mucin-producing congenital iris stromal cyst in a 4 year old patient. OBSERVATIONS: A 4-year old female patient with a history of unilateral congenital iris stromal cyst presented with sudden-onset eye pain and redness, with markedly elevated intraocular pressure and evidence of early optic nerve damage. During the examination under anesthesia, the anterior chamber angle was open and there was no evidence of pupillary block. Ultrasound biomicroscopy revealed mildly echogenic substance filling the anterior chamber suspicious of mucoid material, which was verified by the inability to aspirate the material through a 25 gauge needle. The iris cyst was excised, and the intraocular pressure normalized spontaneously. Pathologic examination confirmed a mucin-secreting iris cyst lined with goblet cells and confirmed the mucogenic mechanism. CONCLUSIONS AND IMPORTANCE: This is the first reported case of mucogenic glaucoma in a pediatric patient. This rare entity should remain on the differential diagnoses of childhood glaucoma associated with nonacquired ocular anomalies. Surgical excision of the iris cyst may be curative.

Introduction

Glaucoma associated with iris cysts is rare, and the mechanisms of intraocular pressure (IOP) elevation include secondary angle closure, pigment dispersion, inflammation and mucin displacing aqueous in the anterior chamber. Here, we describe the first case of glaucoma associated with mucin-producing iris stromal cyst, or mucogenic glaucoma, in a child.

Case report

A 4-year old female first presented to Bascom Palmer Eye Institute at the age of 22 months when her mother noticed an enlarging pigmented lesion on the right iris (Fig. 1). The patient is the product of full-term gestation, delivered by Cesarean section without complications, and is otherwise in good health with normal development. The patient's mother is a carrier of Fragile X mutation, and during gestational week 20, an ultrasound-guided amniocentesis was performed which ruled out Fragile X mutation in the patient. There was no history of ocular trauma. The patient was diagnosed with congenital iris stromal cyst. Between the age of 22 months and 4 years, the patient underwent serial examinations under anesthesia (EUA) by an ocular oncologist every 6 months with IOP in both eyes ranged between 15 and 19 mmHg (Tonopen, Reichert, Depew, New York, USA).

Fig. 1

Clinical photograph of a congenital iris stromal cyst on at age of 22 months.

At the age of 4 years and 9 months, the patient presented emergently with a one-day history of sudden onset pain and redness in the right eye. In the clinic, best-corrected visual acuity was 20/25 in the affected eye, with IOP elevated at 67 mmHg by rebound tonometer (Icare Finland, Oy, Helsinki). There was no afferent pupillary defect. The patient could not cooperate with slit lamp examination, although the anterior chamber is formed and deep on examination using an oblique slit beam from a retinoscope. Topical dorzolamide/timolol fixed-combination therapy was initiated in the right eye twice daily. EUA two days later revealed an IOP of 39 mmHg (Tonopen, Reichert, Depew, New York, USA) in the right eye and 16 mmHg in the left eye under light sedation, and a focal corneal endothelial opacity in the quadrant of the cyst with mild pupillary peaking (Fig. 2). Ultrasound biomicroscopy showed a deep anterior chamber without iris bombé, and a faintly echogenic material filling the anterior chamber (Fig. 3). Gonioscopy revealed wide-open angles (Fig. 4). Examination of the fundus revealed increased cupping of the right optic disc compared to prior photographs (Fig. 5). Axial length by contact A-scan biometry was 21.5 mm on the right and 21.2 mm on the left.

Fig. 2

Clinical photograph of the iris cyst at age 4 years 9 months. The cyst is less discreet in appearance, and there is focal corneal opacity at the quadrant of the cyst. The intraocular pressure is markedly elevated, while the cornea remained clear.

Fig. 3

Ultrasound biomicroscopy examination of the right eye. The anterior chamber is deep with open angles. There is no iris bombé. The anterior chamber is filled with a faintly echogenic material (asterisk).

Fig. 4

Gonioscopic photograph of the superior and inferior angles. The angles in the affected eye were wide-open, with a visible ciliary body band circumferentially.

Fig. 5

Fundus photographs demonstrating no cupping at baseline and an increased cup/disc ratio of approximately 0.55 at age 4 years 9 months.

An attempt to aspirate the anterior chamber content with a 25 gauge needle yielded no fluids, which suggests a secondary open-angle mechanism of IOP elevation due to a viscous fluid displacing the aqueous. The decision was made to excise the iris cyst with concurrent irrigation of the anterior chamber. Following the creation of a large scleral flap of approximately 90% depth (Fig. 6a), two iridotomies were created using a 23 gauge vitrector (Fig. 6b), and a sectoral iris flap was created using intraocular scissors (Fig. 6c, d). The scleral bed was incised and the anterior chamber was entered at the scleral flap hinge, and a large globule of gelatinous material spontaneously presented (Fig. 6e, f). The iris was externalized and was excised at the base (Fig. 6g). The scleral flap was repositioned and closed using interrupted 10-0 nylon sutures followed by closure of the conjunctiva (Fig. 6h).

Fig. 6

Intraoperative photos. a. A large scleral flap is dissected at the quadrant of the iris cyst at approximately 90% depth. b. Ab interno iridotomies were created using a 23 gauge vitrector. c. Iridectomy performed using intraocular scissors connecting the iridotomies to the limbus. d. Iris cyst isolated onto an iris flap by connecting the two iridotomies using intraocular scissors. e. Anterior chamber is entered under the scleral flap, and a globule of gelatinous material spontaneously presented. f. The gelatinous material is removed using surgical sponges and sent as a pathologic specimen. g. The iris flap containing the iris cyst is externalized and excised. h. Scleral flap and conjunctiva reapproximated.

Rebound IOP on the first post-operative day is 20 mmHg. Two months following the cyst excision, the patient had best corrected visual acuity of 20/30 with rebound IOP of 19 mmHg on no glaucoma medications.

On pathologic examination, the iris specimen revealed an epithelial cyst with stratified columnar epithelial and goblet cells; neither atypia nor inflammatory changes were noted (Fig. 7). The globule of gelatinous material stained positively with mucicarmine and was verified as mucin. There were no inflammatory cells on histopathology and staining of the aspirated material.

Fig. 7

a. Periodic acid–Schiff stain of iris and cyst wall. L denotes cyst lumen, which is lined with nonkeratinized stratified columnar epithelium with goblet cells. b. Goblet cells and mucin stained with mucicarmine stain. Arrows – goblet cells, black asterisks – iris stroma, white asterisks – iris pigment epithelium.

Discussion

Glaucoma associated with a mucin-producing iris cyst, or mucogenic glaucoma, is an extremely rare form of secondary open-angle glaucoma. To the authors' knowledge, this is the fifth reported case overall, and the first in a child.1, 2, a, b, 3, 4 In all cases, patients presented with acute elevations in IOP concurrent with clinical suspicion of ruptured iris cyst. With variable follow up between 16 months and 6 years, excision of the cyst was deemed curative.1, 2, a, b, 3, 4 All pathologic specimens showed epithelial cells and ruptured cyst with mucin. Goblet cells were found in 3 out of 4 previously reported cases. Overall, only two of the five cases had a history of open-globe trauma, during which the ectopic epithelium was thought to have been seeded.2, a, b, 3, 4 Our patient had no postnatal history of ocular trauma, although there was an antenatal history of real-time, ultrasound-guided amniocentesis. Amniocentesis-related ocular trauma has been implicated in nonpigmented epithelial iris cysts previously, though none have resulted in secondary glaucoma.5, 6

Wakae et al. described the intraoperative technique of using a 25 gauge needle aspiration of anterior chamber to discern between aqueous and mucin. In our case, no sample was obtainable using the 25 gauge needle, which lead to the decision to excise the cyst instead of implanting a glaucoma drainage device or ab interno trabeculotomy as the means of IOP control in this child. Of note, although the history of glaucomatous damage and elevated IOP in our patient is not in dispute, the precise IOP measurements upon presentation may be unknown as the anterior chamber was filled with a gelatinous material rather than aqueous.

Conclusion

Mucogenic glaucoma should be on the differential diagnosis of childhood glaucoma associated with nonacquired ocular anomalies. Aspiration of the anterior chamber using a 25 gauge needle is an important diagnostic maneuver to confirm the presence of viscous material, and excision of the cyst may be curative.

Patient consent

Consent to publish the case report was not obtained. This report does not contain any personal information that could lead to the identification of the patient.

Funding

None.

Authorship

All authors attest that they meet the current ICMJE criteria for Authorship.

Conflict of interest

None.