Optical Coherence Tomographic Findings of Combined Hamartoma of the Retina and Retinal Pigment Epithelium in 11 Patients

Combined hamartoma of the retina and retinal pigment epithelium (RPE) is an uncommon fundus tumor with classic clinical features.¹ In 1984, Schachat et al² published 60 cases collected from the members of the Macula Society and described the clinical features and natural course of this benign lesion. They noted that the lesion was typically pigmented (52 cases [87%]), elevated (48 cases [80%]), and had vascular tortuosity (56 cases [93%]), vitreoretinal interface changes (47 cases [78%]), and lipid exudate (4 cases [7%]). The vitreoretinal interface changes in that series of patients were appreciated on ophthalmoscopic examination as surface wrinkling retinopathy and also, to some extent, were inferred based on fluorescein angiography as vascular dragging. In their series, progressive loss of visual acuity due to tractional distortion of the fovea from vitreoretinal interface problems was observed in 14 (24%) of 60 cases. The importance of the vitreoretinal interface in this condition and particularly as a risk for visual loss was recognized, but it was not yet completely understood. Speculation existed regarding the depth of the tractional component, whether it involved the surface or deep layers, and controversy arose regarding the benefits of surgical removal of the tractional component.^2,3 At that time, high-resolution, cross-sectional analysis of the retina was unavailable for visualization of vitreoretinal interface abnormalities.

Twenty years later, we further investigate the vitreoretinal interface abnormalities and retinal microarchitecture of combined hamartoma of the retina and RPE using optical coherence tomography (OCT). Previously presumed findings or those that were difficult to document, such as vitreoretinal interface abnormalities, can be imaged remarkably well with OCT. In this article, we examined 11 consecutive patients who had combined hamartoma of the retina and RPE using OCT.

The clinical records of all patients having the diagnosis of combined hamartoma of the retina and RPE and imaged with OCT (Zeiss Stratus OCT model 3000; Carl Zeiss Ophthalmic Systems, Dublin, Calif) on the Ocular Oncology Service at Wills Eye Hospital, Philadelphia, Pa, between January 1, 2003, and April 1, 2004, were reviewed. Institutional review board approval was obtained. Data were gathered regarding clinical, OCT, and ultrasonographic features of the combined hamartoma and the vitreous overlying the tumor using the 6 radial lines acquisition protocol. The retinal thickness analysis protocol was used to measure the greatest thickness of the tumor. Confirmation of retinal thickness was performed by measuring the greatest thickness using computer calipers. By comparison, retinal thickness analysis was performed, whenever possible, on the healthy opposite retina in a mirrored location or in the same eye at the immediately adjacent healthy retina.

The general clinical data included patient features at initial examination such as age, sex, and race. The ocular data included visual acuity, symptoms, tumor color, tumor quadrant and anteroposterior location, tumor distance to the optic disc and foveola, and largest tumor basal dimension and thickness. Additional clinical data at the site of the combined hamartoma included the presence of posterior vitreous detachment, preretinal fibrosis, retinal exudation, retinal edema, retinal hemorrhage, retinal atrophy, subretinal fluid, and RPE hyperplasia or atrophy. The OCT data at the site of the combined hamartoma included presence of posterior vitreous detachment, vitreoretinal traction, preretinal membrane, retinal striae, retinal disorganization, retinal edema, subretinal fluid, and RPE irregularity or detachment. Optical reflectivity of the inner and outer portions of the tumor were recorded. Retinal edema was classified as cystoid vs noncystoid based on the presence or absence of intraretinal optically lucent cysts. The macula was defined as the round area within 3 mm of the foveola.

There were 11 consecutive patients who had a combined hamartoma of the retina and RPE imaged with OCT. The clinical features are listed in Table 1. In all cases, the tumor was unilateral and unifocal and appeared to be gray-brown. The initial symptom at presentation was blurred vision (n = 6), strabismus (n = 2), or asymptomatic (n = 3). The meridional location of the tumor was macula (n = 8), inferior (n = 1), and nasal (n = 2). The mean basal dimension of the tumor was 7 mm (median, 7 mm) and the mean thickness of the tumor as measured by ultrasonography was 1.8 mm (median, 2.0 mm). The tumor margin was a mean of 0.2 mm to the optic disc (median, 0 mm; range, 0-2.0 mm) and a mean of 0.4 mm from the foveola (median, 0 mm; range, 0-2.0 mm). Choroidal neovascularization was not present in any patient by clinical examination or OCT.

The OCT findings are listed in Table 2. A preretinal membrane was visualized by OCT in 10 patients. The preretinal membrane was configured in peaks, reflecting vitreoretinal traction in 3 patients (Figure 1). The retina was drawn into folds or striae by preretinal membrane in 9 patients (Figures 2, 3, and 4). Retinal anatomical disorganization with loss of identifiable retinal layers at the site of the mass was noted in all patients (Figures 1, 2, 3, and 4). The mean retinal thickness at the site of the lesion was 766 μm (median, 790 μm). The adjacent flat retina appeared to be of normal thickness and anatomical configuration.

Ultrasonography was performed on 8 patients and revealed no evidence of posterior vitreous detachment, vitreous traction, or preretinal membrane in any patient. The lesion showed acoustic features of echolucency (n = 2), echodensity (n = 0), and isodensity (n = 6). There was no acoustic shadowing or intralesional calcification in any patient.

Epiretinal membrane formation is a prominent clinical feature of combined hamartoma of the retina and RPE.² In the collaborative report by Schachat et al,² only 3 of 60 patients had surgical removal of the epiretinal membrane; visual improvement was achieved in 1 patient. Histopathologic findings of those membranes showed fibrous astrocytes, fibrocytes, fragments of the internal limiting membrane, new collagen, and vitreous collagen. McDonald et al⁴ described 2 patients with combined hamartoma of the retina and RPE in which surgical removal of epiretinal membrane was performed and visual acuity did not improve in either case. It has been speculated that irreversible visual loss was present in these slightly older patients (ages 44 and 26 years) with a presumed congenital tumor. Perhaps earlier intervention would have been warranted.⁵ Stallman⁵ and Mason and Kleiner⁶ each reported a case of visual improvement following surgical removal of epiretinal membrane in younger patients with combined hamartoma. The benefits of surgery in such cases and the overriding influence of amblyopia continues to be debated.

In a discussion, Gass³ speculated that the membrane might be intricately interwoven within the dysplastic retina. Stallman⁵ later commented that the membrane was surgically separable from the tumor so it most likely was extrinsic to the retinal tumor. He suggested newer imaging modalities such as OCT to delineate the precise location of the membrane as it could influence the surgeon’s approach to this mass.

In 2002, Ting et al⁷ reported the first observations on OCT of combined hamartoma of the retina and RPE in 2 adult patients. They noted important findings such as a thickened retinal mass with hyperreflective surface and deep shadowing and they commented that the adjacent retina appeared to be normal and separate from the mass. Cystoid edema was found in 1 patient. In our series of 11 patients, we contribute several additional observations regarding OCT of this lesion. Eight of our 11 patients were teenagers or children. Optical coherence tomography is fairly well tolerated by children and provides more clinical detail of the retina than is visible by indirect ophthalmoscopy or ultrasonography.⁸ We observed a distinct epiretinal membrane with secondary retinal folds and striae in almost all patients. The membrane showed horizontal traction in 9 patients and vertical traction with peaks in 3 patients. The membrane was preretinal with no evidence of intertwining into the tumor. Additional findings included retinal disorganization in all patients. The adjacent retina was normal in architecture and seemed to gradually thicken into the disorganized tissue. One might speculate that the tractional component from the epiretinal membrane was the sole source for the distorted retinal findings. However, others have speculated that the epiretinal component could be secondary to the retinal tumor.⁵

Despite the fact that all but 3 of our patients were children or teenagers and the disease seemed to be detected early in life, the tractional forces of the epiretinal membrane were associated with severe retinal microarchitecture compromise. Future studies are needed to evaluate the effect of earlier detection and delamination of the epiretinal membrane in prevention of permanent retinal disorganization and visual loss. Optical coherence tomography can provide important information regarding the vitreoretinal interface of this tumor and could influence surgical decisions.

Correspondence: Dr C. L. Shields, Ocular Oncology Service, Wills Eye Hospital, 840 Walnut St, Philadelphia, PA 19107 (carol.shields@shieldsoncology.com).

Financial Disclosure: None.

Funding/Support: This study was supported by the Eye Tumor Research Foundation, Philadelphia, Pa (Dr C. L. Shields), the Macula Foundation, New York, NY (Dr C. L. Shields), the Rosenthal Award of the Macula Society, Barcelona, Spain (Dr C. L. Shields), and the Paul Kayser International Award of Merit in Retina Research, Houston, Tex (Dr J. A. Shields).