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Spontaneous Incomplete Avulsion of Juxtafoveal Retinal Pigment Epithelial Hamartoma
Arch Ophthalmol. 2001;119:903-907.
INTRODUCTION
Focal congenital anomalies of the retinal pigment epithelium (RPE) have recently been classified by Gass1-2 into 4 categories: RPE hamartoma, combined RPE and retinal hamartoma, melanotic nevi of the RPE (congenital hypertrophy of the RPE), and amelanotic nevi of the RPE. Retinal pigment epithelium hamartomas are typically seen in the temporal macular area of normal children or young adults on routine eye examination and do not change in size over time.1-3
Several complications resulting in visual impairment have been described in association with hamartomatous lesions of the RPE, the retina, and the retinal vessels. These have most commonly been noted in the presence of retinal capillary hemangiomas and include vitreous hemorrhage, intraretinal exudation, epiretinal formation and exudative, tractional and rhegmatogenous retinal detachment.4-6 Here we report 2 cases of incomplete avulsion of a juxtafoveal RPE hamartoma resulting in a prefoveal mobile tumor in one case and a full-thickness retinal hole in the other.
Report of Cases
Case 1
A 33-year-old Belgian man initially noted "black dots" and a mobile opacity in his right central visual field. The visual acuity varied from 6/60 to 6/12 OD and was 6/6 OS . His ocular medical history was remarkable for an asymptomatic "brown spot" in the back of his right eye, which was noticed during a routine eye examination in Belgium 12 years previously and considered to represent a benign lesion. Fundus photographs were not obtained at that time.
Funduscopy showed a pigmented small preretinal tumor in the posterior pole that was connected to the retinal surface at its upper temporal aspect by a small pedicle (Figure 1). The tumor took variable positions depending on eye movements. A partial posterior vitreous detachment was present in the right eye with persistent adherence to the pigmented lesion. In addition, a mild vitreous hemorrhage was noted in the right eye. Funduscopy in the left eye was unremarkable and there was no posterior vitreous detachment.
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Figure 1. Case 1. Fundus photograph showing prefoveal, partially avulsed pigmented tumor that is connected to the retina by a small pedicle at the superior nasal aspect and contains the feeding and draining vessel.
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Results of angiographic studies with fluorescein and indocyanine green angiography using confocal scanning laser ophthlamoscopy7 disclosed an afferent and an efferent tumor vessel communicating with the retinal circulation (Figure 2). Staining of the tumor and leakage of fluorescein dye into the vitreous cavity were noted in the late frames during angiography. The vitreous hemorrhage spontaneously resolved during the subsequent clinical course. However, the patient continued to complain about the mobile "shadow" in his right eye. Therefore, it was elected to perform vitrectomy and excisional biopsy as well as endodiathermy of the retinal site where the feeding and draining vessels entered the retinal circulation. During vitrectomy there was an obvious firm adherence of the posterior vitreous to the mobile tumor. Visual acuity was 6/9 OD after surgery with no evidence for recurrent vitreous hemorrhage (Figure 3).
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Figure 2. Case 1. A, Early fluorescein angiogram showing an efferent vessel from the retinal circulation into the pigmented hypofluorescent tumor. B, Indocyanine green angiogram. Note the feeding and draining vessels of the tumor that functions as an arteriovenous shunt. C and D, Late-phase fluorescein angiogram showing staining of tumor tissue and leakage of fluorescein dye into the vitreous.
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Figure 3. Case 1. Fundus of the right eye after vitrectomy and exudation biopsy as well as diathermy of the draining and feeding vessels. There is a partial thickness retinal defect as well as a reactive pigmentary abnormality at the original tumor site.
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Findings from histological examination showed a biphasic appearance with pigmented cells and small capillaries (Figure 4A). Dense, thick-walled vascular channels with factor VIII–positive endothelium were surrounded by tubules and cords of melanin-containing cells (Figure 4 B). Occasional fragments of glial fibrillary acid protein–positive tissue were present. The tumor contained 2 features: an angiomatous lesion and hyperplasia of the RPE.
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Figure 4. Case 1. A, Photomicrograph of the tumor showing thick-walled vascular channels surrounded by tubules and cords of pigmented cells (hematoxylin-eosin, x200). B, Factor VIII immunoreactivity showing the vascular component of the tumor with dense small vessels (immunoreactive, x400).
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Case 2
A healthy 10-year-old Greek boy was noted to have a unilateral dark brown retinal tumor temporal to the right fovea during a routine eye examination (Figure 5A). There was a nodular component of the tumor extending anterior to the surrounding retinal surface. His visual acuity was 6/12 OD and 6/6 OS. His ocular and medical histories were unremarkable. Seven years later he noted a sudden paracentral scotoma and a mobile opacity. Funduscopy disclosed a full-thickness retinal hole adjacent to the fovea, while the brown tumor was incompletely avulsed with a small connection to the neurosensory retina at the temporal aspect of the tumor (Figure 5B). There was a rim of thickened or detached retina. A posterior vitreous detachment was present in the right but not in the left eye. His visual acuity was 6/18 OD. Prophylactic laser photocoagulation to prevent a rhegmatogenous detachment was applied to the margins of the hole sparing the fovea. A small pigmented rim of chorioretinal scars subsequently developed at the lasered area (Figure 5C). At that time visual acuity remained 6/18 OD. The patient was lost to follow-up.
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Figure 5. Case 2. A, A hypermelanotic lesion is present in the temporal macular area of a 10-year-old boy. B, After incomplete avulsion a wedge-shaped, full-thickness retinal hole is seen extending to the fovea. The tumor is still attached to the neurosensory retina at the temporal aspect. C, Following laser photocoagulation sparing the fovea, pigmented chorioretinal scars have formed at the margin of the retinal hole.
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Comment
The usually benign course of RPE hamartoma located superficially in the retina or extending through the entire retina may be complicated by incomplete avulsion. We speculate that permeability alterations of the vascular component of RPE hamartomatous lesions are the responsible underlying mechanism for the avulsion. Both patients were young individuals and the affected eyes were emmetropic. However, there was a partial posterior vitreous detachment present with an abnormal vitreoretinal adherence at the superior tumor surface in the affected eyes, while there was no posterior vitreous detachment in the fellow eyes. Angiographic studies in one patient disclosed staining and leakage of fluorescein dye from the tumor in the presence of a prominent vascular component later seen on histological examination. It is assumed that exudation from the lesions over many years into the vitreous cavity resulted in vitreal changes with premature liquefaction and degenerative alterations that, in turn, induced a posterior vitreous detachment. In addition, exudation may have led to the formation of an abnormal vitreoretinal adherence to the tumor surface. The posterior vitreous detachment presumably caused traction and the presence of the firm adhesions of the posterior vitreous to the hamartoma, thus inducing the avulsion.
Complications in the presence of hamartomatous retinal lesions have most commonly been described in association with retinal vascular hamartomas, ie, capillary hemangiomas. These include epiretinal membrane formation,3-4,6, 8 vitreous traction, traction retinal detachment, exudative retinal detachment,6 rhegmatogenous retinal detachment,9 vitreous hemorrhage, secondary retinoschisis,10 and intraretinal exudation with macular edema.1, 11 An incomplete symptomatic avulsion of RPE hamartoma has, to our knowledge, not been previously described.
Focal congenital anomalies of the RPE have recently been classified by Gass into 4 categories: RPE hamartoma, combined RPE and retinal hamartoma, melanotic nevi of the RPE (congenital hypertrophy of the RPE), and amelanotic nevi of the RPE.1-2 Alternative terms for RPE hamartomas introduced in the literature include primary hyperplasia of the RPE and pigment epithelial adenoma. Retinal pigment epithelium hamartomas are rare lesions composed of hyperplastic RPE and may contain a variable number of blood vessels.1-3 There was a prominent angiomatous component in our first patient on histopathological examination. Retinal pigment epithelium hamartomas are frequently located in the temporal macular area, are typically 0.5 to 1 disc diameter, and tend not to enlarge over time; in addition, the affected eye may be mildly amblyopic. They vary in depth regarding the intraretinal extension, and a preretinal extension may occur.1 The fact that many cases are diagnosed at a young age led to the hypothesis that they represent congenital lesions.3-4,12 However, the diagnosis of a congenital lesion is always one of presumption since postnatal injuries may cause reactive RPE changes that mimic developmental lesions. Even histopathological examination does not allow for a clear differentiation between these two categories. Since RPE hamartomas are uncommon, and, even more important, complications in association with these lesions would necessitate removal of the abnormal tissue, very few histopathological reports are available to date.12-15 Some eyes were enucleated because of suspected melanomas whereby histopathological examinations showed lesions consistent with large RPE hamartomas.16-21
Retinal pigment epithelium hamartomas differ from melanotic nevi (congenital hypertrophy of the RPE) histologically in that the latter usually consist of a single layer of enlarged RPE cells filled with large melanin granules.1 However, some causes of congenital RPE hypertophy may be associated with some evidence of hyperplasia of multiple cell layers. There is no migration of RPE cells and no vascular component. In addition, melanotic nevi are usually well demarcated and encompass depigmented lacunae. Combined retinal and RPE hamartomas are seen as slightly elevated mottled pigmented tumors with ill-defined borders often involving the optic nerve head. They represent dysplastic tumors composed of disorganized retinal tissue with vascular and glial elements as well as RPE hyperplasia. In addition, they are often associated with a change in the vitreoretinal interface and a crinkled epiretinal membrane.
Functional results of vitreoretinal surgery for complicating epiretinal membranes associated with combined retinal and RPE hamartomas were found to be disappointing and prompted McDonald and coworkers8 not to recommend surgical intervention for such cases. Since the clinical course after vitrectomy and removal of the incompletely avulsed RPE hamartoma described herein was favorable, surgery appears to be an option for this particular complication.
To our knowledge, neither avulsion of RPE hamartoma resulting in prefoveal location nor full-thickness juxtafoveal retinal macular hole formation has been reported as a complication of congenital RPE hamartomas. If visual impairment results from a subsequent prefoveal location of the mobile tumor, vitrectomy and excisional biopsy should be considered. Alternatively, if a full-thickness extrafoveal retinal hole develops, management with laser photocoagulation sparing the fovea may be performed as a prophylactic measure to prevent further visual loss.
AUTHOR INFORMATION
Presented in part at the Atlantic Coast Retinal Meeting, New York, NY, January 14, 2000, and the Annual European Ophthalmic Pathology SocietyMeeting, Heidelberg, Germany, June 5, 2000.
Corresponding author and reprints: Frank G. Holz, MD, Department of Ophthalmology, University of Heidelberg Im Neuenheimer Feld 400, D-69120 Heidelberg, Germany (e-mail: frank_holz{at}med.uni-heidelberg.de).
Frank G. Holz, MD;
Evangelos Alexandridis, MD;
Hans E. Völcker, MD
Heidelberg, Germany
Stefan Dithmar, MD;
Hans E. Grossniklaus
Atlanta, Ga
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SECTION EDITOR: W. RICHARD GREEN, MD
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