Primary Pupillary Margin Cyst of the Iris Pigment Epithelium

doi:10.4236/cm.2011.21003

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Chinese Medicine, 2011, 2, 16-19

doi:10.4236/cm.2011.21003 Published Online March 2011 (http://www.SciRP.org/journal/cm)

Primary Pupillary Margin Cyst of the Iris Pigment

Epithelium

Rosanna Dammacco1, Giovanni Giancipoli1, Silvana Guerriero1,

Domenico P iscite l li2, Nicola Cardascia1

1Department of Ophthalmology and Otorhinolaryngology, Bari University, Bari, Ita ly

2Department of Pathological Anatomy, Bari Unive rsity, Bar i, Italy

E-mail: [email protected]

Received

January 13, 2011; revised February 2, 2011; accepted February 10, 2011

Abstract

Purpose: Description of a patient with a solitary cyst of the pupillary margin iris pigment epithelium (IPE).

Methods: A 63-year-old man referred a suspected iris-ciliary body melanoma in his left eye. Based on both

clinical examination and ultrasound biomicroscopy, melanoma was considered unlikely. Surgery was under-

taken to correct recurrent deterioration of vision due to movement of the lesion across the visual axis. Results:

The lesion was excised completely. Ultrasound biomicroscopy and histopathological examination ruled out

melanoma and allowed a final diagnosis of primary pupillary margin cyst of the IPE, characterized of pig-

mented epithelium, with no connective tissue or vessels. No recurrences or fresh lesions appeared during a

one-year follow-up. Conclusions: Primary epithelial iris cysts are usually benign. Treatment is required only

in symptomatic patients and those with an uncertain diagnosis. Ultrasound biomicroscopy is indispensable to

confirm the clinical diagnosis, follow the clinical course and intervene if surgery is required.

Keywords: Melanoma, I ris Pigment E pithe lium, P up illary Cyst, S urgical Excision, Ultrasound Biomicroscopy

1. Introduction

Primary cysts in t he anterior segment, observed during a

routine eye examination, are divided into stromal and

pigment epithelial cysts [1 ]. Primary stromal cysts are

less common and mostly congenital [2]. Their differen-

tial diagnosis from malignant uveal melanoma may

sometimes be difficult. Primary cysts are of neuroepi-

thelial origin, whereas secondary cysts may result from

intraocular implantation of surface epithelium following

surgery or a penetrating trauma, or else from metastasis,

parasites, or chronic myotic therapy [3]. Neuroepithelial

cysts involve the iris pigment epithelium (IPE) and the

ciliary bod y [4].

Primary cysts of the IPE are uncommon and sponta-

neous. T hey are defined as epithelial-lined struc tur es t hat

arise in t he poster ior iris layer [ 5 ] . Shields (1981) distin-

guishes four t ypes, according to their po sition in rela tion

to the iris [1]: c entral, at the pupillar y mar gin; midzonal,

between the pupillary margin and the iris roo t; peripheral,

at the iridociliary sulcus; dislodged, in the anterior

chamber or the vitreous cavity. The vast majority (76%)

is peripheral [1].

This paper describes a case of symptomatic primary

central IPE cyst initially mistaken for an iris melanoma.

Stress is laid on ultrasound biomicroscopy (UBM) as a

noninvasive way of determining the nature of a cyst,

establishing its final diagnosis and following its course.

2. Case Report

A 63-year-old man presented with a two-month history

of disturbed vision in his left eye and a suspected iris

melanoma. In distant vision, his best corrected visual

acuity (BCVA) was 20/20 in both eyes, but his left-eye

disturbance was aggravated by strong daylight, which

caused a severe temporary deterioration of vision (≤

20/50). Slit-lamp examination showed a solitary, homo-

geneously pigmented mass hanging at the superior pu-

pillary margin of the iris and at 1 o’clock in the anterior

chamber (Figure 1). It slowly moved when the patient

changed the position of his head. It was smooth,

dark-brown and apparently cystic. The pupil was round,

readily reacting to light and accomodation. During mi-

osis, the lesion often obstructed the pupillary aperture.

The slit lamp also revealed a normal left external eye,

R. DAMMACC O ET AL.

cornea and conjunctiva, both before and after papilla ry

dilatation, with no signs of inflammation in the anterior

chamber. The right eye was normal. Examination with a

Goldmann goniolens disclosed normal angular structures

in both eyes. A Gold mann ap planation tonometer sho wed

an intraocular pressure of 14 mmHg in each eye. The

fundi oculi were unexceptional. UBM of each eye was

performed with a Humphrey 840 instrument, using a 50

MHz probe and an immersion technique. An immersion

scleral shell was placed on the globe between the eyelids

and filled with 2% methylcellulose. The probe was

moved at right angles to produce radial and transverse

sections. A 5 x 5 mm cyst with a thin, mediu m re flective

wall and acoustically clear content (Figure 2) was ob-

served in the left eye. The patient was dul y informed that

his cyst could be removed or kept under regular observa-

tion.

He chose surgery because of his disturbing visual

Figure 1. Solitary, dark-brow n cyst in the supero-temporal

aspect of t he p upillary margin.

Figure 2. Ultrasound biomicroscopy of the left eye shows a

pigmented cyst with a thin, medium reflective wall and

acoustically clear contents, measuring 5.0 × 5.0 mm of di-

ameter.

symptoms. Surgery was then performed under topical

anesthesia. A blade was used to make a 3-mm limbal

section, followed by controlled entry into the anterior

chamber. Do wnward ro tation of the globe resulted in the

spo ntaneous r upture and coll apse of the cyst. I t was the n

extruded through the limbal section (Fig ure 3). The

wound was closed with a single 10-0 monofilament ny-

lon suture. Transmission electron microscopy was used

to examine the structure of the wall (Figure 4). Histo-

logically, the iris simplex cyst is break off and partially

lined by are present (Figure 5). It was therefore classed

according to Shields [1] as a primary pupillary margin

IPE cyst. After surgery, topical 0.1% fluorometholone

was ad ministered 4 times a day. One week later, BCVA

was 20/20 in both dis tant a nd near vi sion. T he i ntraoc ular

Figure 3. As the globe was rotated downwards, the cyst

spontaneously ruptured, collapsed and was then extruded

out through t he li mb al se ction.

Figure 4 . Microvil lous pr oces sis are evident alo ng t he apical

port ions of t he cell s, con necting by occlu dens an d adherens

junctions. Small round or ovoid granules in early stages of

melanization are seen (TEM; original magnification 11500 x).

R. DAMMACC O ET AL.

Figure 5. Hi stopatholog ical ex amin ation of th e tissue sh ows

that it consists entirely of pigmented epithelium without

connective tissue or vascular el ements.

pressure, the shape of the anterior chamber and the reac-

tion of the pupil to light were normal.

3. Discussion

Primary IPE cysts are found anywhere along the post-

erior surface of the iris from the pupillary margin to the

anterior ciliary body. The great majority are stationary

and small, and sometimes regress spontaneously. Their

presence is occasionally responsible for angle closure

glaucoma, plateau iris syndrome and secondary pigment

dispersion syndrome. [6-9]. Central cysts account for

approximately 3% of all primary IPE cysts [1,5]. They

are usually dark brown, round or oval with a thin wall

and sonolucent contents [1-5 ] . The high reflectivity of

their wall is attributed to the epithelial cells, while their

sonolucent core is compatible with a fluid content. The

origin of primary central IPE cysts is not clear. Their

appearance in early childhood in a few familial cases

suggests that they may be hereditary with an autosoma l-

dominant pattern [7-10]. Lewis et al. [11] described an

association with familial aortic dissection. Sallo and

Hatvani [12] reported four cases of primary pupillary

IPE cysts in a single family. These patients also suffered

fro m transie nt vis ion d istur banc es. O ur pati ent, ho weve r,

had no history of associated systemic diseases and no

other membe r of hi s fa mi l y ha d a cyst . P r imar y I P E cysts

have often been misdiagnosed as iris or ciliary body me-

lanoma [13]. Cysts of the iris are more likely to be con-

fused with melanoma than those of ciliary body because

of their pigmentation and more anterior location. Diag-

nosis and monitoring of iris, ciliary body and posterior

chamber cysts require the imaging of structures not al-

ways visible with a slit lamp and go ni olens, even through

a dilated pupil. UBM has thus become indispensable for

evaluating anterior segment tumors and cysts and is used

to confirm a clinical diagnosis of primary IPE cysts, dif-

ferentiate them from cystic and solid tumors (iris-ciliary

body melanoma and melanocytoma, adenoma of the IPE

and medulloepithelioma), follow their course and

pro mptl y inte rvene i f s ur gery is r eq uir e d. I t al so p ro vid e s

cross-sectional images illustrating the surface contour,

internal reflectivity and borders, and reveals their size,

extension and site. Management is determined by a

cyst’s site, size, local extent and growth pattern, and the

presence of secondary complications. Most primary IPE

cysts run a benign clinical course that seldom results in

ocular complications. They are usually small and fre-

quently regress spontaneously. Those that arise from the

IPE layers are stationary, asymptomatic, and detected

only incide ntally. Shield s beli eves that most pri mary IPE

cysts are ophthalmic curiosities that need prolonged ob-

servation and no treatment [1]. A steadily growing cyst,

however, may disturb vision by covering the visual axis

and provoke an increase in intraocular pressure or even

inflammation i f it to uches t he cor neal endotheli u m. Steps

must then be taken to prevent or treat complications,

such as pupillary obstruction, secondary glaucoma, iri-

docyclitis, corneal decompensation and loss of vision.

Numerous forms of managements have been employed.

Mitomycin injection into the cyst and needle aspiration

with endodiathermy were proposed by Kawaguchi et al.

[14] and Tsai et al. [15]. Kuchenbecker et al. [16], Öner

et al. [17] and Baykara et al. [18] prefer Nd:YAG laser

cystotomy as the least invasive procedure. Excision in

our case, like in that reported by Verma et al. [19], was

dictated by the fact that in strong daylight the cyst ob-

scured the visual axis almost completely and caused a

severe temporary decrease of visual acuity. There were

no complications and no clinical or UBM evidence of

recurrences or fresh lesions during a one-year follow-up.

In conclusion, in agreement with most authors we be-

lieve that stable and asymptomatic primary IPE cysts

usual ly requi re no more than regular o bserva tion. P roper

treatment depends on the overall clinical picture, which

includes both the patient’s general health and the size

and location of the cyst. Lastly, the importance of early

diagnosis should be stressed. UBM is a useful, readily

available and noninvasive tool for this purpose, since it

can be employed to both confirm the clinical diagnosis

and follow the course of these cysts. We address future

studies on anterior chamber OCT to “in vivo” analyze

cyst morphology.

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R. DAMMACC O ET AL.

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