Multimodal imaging of combined hamartoma of the retina and retinal pigment epithelium associated with an acquired vitelliform lesion

A healthy 25-year-old white male presented complaining of a gradual and progressive visual disturbance in his left eye for 6 months. His Snellen best corrected visual acuity was 20/20 in each eye and the anterior segment examination was unremarkable bilaterally. Dilated fundoscopy of the right eye was normal; fundoscopy of the left eye showed a slightly elevated greyish lesion with scattered pigmentary changes superior to the optic nerve which extended in a fan-like distribution from the optic nerve (Fig. 1). There were tortuous fine retinal vessels overlying the lesion with radial retinal folds that appeared to be emanating from the infero-temporal aspect of the lesion. The folds extended into the macula and a small intraretinal hemorrhage was noted at the superior macula along with a vitelliform lesion near the fovea.

SD-OCT through the tumor showed thickening and disorganization of the inner and outer retina with marked saw-tooth like corrugations along the vitreoretinal interface (Fig. 1). The subfoveal vitelliform lesion appeared hyperreflective with preservation of the external limiting membrane and ellipsoid layer at the site of the lesion. SD-OCT also revealed the presence of an epiretinal membrane with contraction of the inner retinal layers of the macula.

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Fundus autofluorescence showed intense hyperautofluorescence from the vitelliform lesion as well as granular hypoautofluorescence inferotemporal to the lesion (Fig. 2). A linear masking of the background autofluorescence was visible in the area of the intraretinal hemorrhage. While retinal autofluorescence was obscured at the superior optic nerve head margin, a notable, large, speckled pattern of hypoautofluorescence was visible surrounding the optic disc and extending well beyond the clinically visible boundaries of the lesion along its entire perimeter. Early hyperfluorescence of the combined hamartoma was visible in fluorescein angiography along with an increased intrinsic vascularity within the lesion itself (Fig. 2).

OCTA revealed significant distortion of the retinal microcirculation intralesionally along the radial peripapillary capillary network superior and superotemporally to the optic nerve head with vessels appearing fine and tortuous in a corkscrew pattern (Fig. 3). Surrounding this network of corkscrew vessels were straight radial vessels normally found in a physiological peripapillary capillary network.

Similar to the description of combined hamartomas by Gass in 1973 [1], our patient presented with a unilateral grey lesion that was slightly elevated, involving the RPE, retina and the overlying vitreous which extended in a fan-like projection towards the periphery and blended imperceptibly with the surrounding tissue. After the initial identification of combined hamartomas by Gass, many other studies have documented common manifestations observed with these tumors, including a study by Shields et al. [4]. In a similar study of 60 patients, combined hamartomas are described as having vascular tortuosity (93 %), pigmentation (87 %), elevation (80 %), vitreoretinal interface disturbances (78 %), and lipid exudation (7 %) [14].

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These observed clinical characteristics are confirmed and further elaborated with the aid of multimodal imaging, including novel techniques such as OCTA, which allowed for depiction of the tumor’s vasculature without the need for intravenous dye injection and without the limits in resolution arising from extravasation of fluorescein dye [15]. OCTA confirms and topographically maps out the increased and seemingly disorganized vasculature in the tumor as previously described [3, 14]. While the presence of thickened glial and retinal tissue makes it difficult to view the vascular architecture on fundoscopic examination, OCTA isolates and enables clear visualization of the vascular network.

Our patient manifested many of the characteristics mentioned above. However, he presented uniquely with a subfoveal acquired vitelliform lesion in the setting of traction occurring at the vitreoretinal interface. Acquired vitelliform lesions are known to occur in tractional maculopathies in which significant vitreomacular traction is present [16, 17]. For instance, in a study of 87 patients with unilateral epiretinal membrane, a subfoveal vitelliform lesion was found in 15 patients (17.2 %) compared to only 5 patients (5.7 %) in matched control fellow eyes (p = 0.03) [17]. According to Freund et al., normal apposition between the photoreceptor tips and the RPE is disrupted by tractional forces which can interfere with phagocytosis of shed outer segments in the RPE [16]. Subsequent accumulation of lipid-laden macrophages and RPE cells may account for the yellow vitelliform collection which appears hyperreflective on SD-OCT [16]. The common natural progression of AVLs is gradual absorption of the lesion with subsequent atrophy or, in rare cases, formation of a macular hole; both scenarios lead to poor visual outcomes [18-20].

A combined hamartoma can cause visual impairment in several ways, but vision loss most commonly occurs when retinal dragging causes foveal distortion [11, 14, 21]. When significant visual impairment is observed secondary to fovea-involving traction, treatment options include surgery to relieve the vitreomacular tractional component. Surgical management, however, remains controversial, as previous reports documenting visual improvement following vitrectomy and membrane peeling are anecdotal [22-25]. While combined hamartoma is a benign tumor, macular edema and choroidal neovascularization (CNV) can occur in association with these lesions, which can lead to a poor visual outcome [26]. Treatment of CNV in the past has included photodynamic therapy and laser photocoagulation but, more recently, intravitreal antiangiogenic injections have been utilized [27, 28].

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