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Optic Disc Tuber
Michael C. Brodsky, MD;
Ammar N. Safar, MD
Arch Ophthalmol. 2007;125(5):710-712.
Tuberous sclerosis is an autosomal-dominant disorder characterized by enhanced proliferation of neural and astrocytic precursors. It is caused by mutations in either TSC1 or TSC2, with loss of hamartin or tuberin function.1 Affected patients exhibit a specific constellation of neurologic, cutaneous, visceral, and retinal lesions.2 The classic triad of epilepsy, adenoma sebaceum, and mental retardation is found in less than one third of cases diagnosed by current criteria.2
Unilateral optic disc elevation in tuberous sclerosis is usually attributable to an astrocytic hamartoma on the surface of the optic disc.3-4 These phakomas may gradually calcify but generally do not enlarge.3-4 We document preservation of vision despite massive enlargement of a tumor situated within the optic disc in a child with tuberous sclerosis.
Report of a Case
A 19-month-old girl was found to have swelling of the right optic disc. She had developed seizures at 6 weeks of age, which were controlled with carbamazepine. At 6 months of age, she had been diagnosed with tuberous sclerosis when magnetic resonance imaging disclosed multiple subependymal nodules and cortical tubers without ventriculomegaly. She had a hypopigmented macule and multiple ash-leaf spots on her legs and trunk. At 7 years of age, she developed a trace afferent pupillary defect in the right eye with no corollary change in her vision or optic disc appearance (Figure A).
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Figure. A, Optic disc photography shows smooth elevation of the optic disc and peripapillary retina, with no obscuration of vessels at age 7 years. B, Optic disc photography shows increased elevation of the optic disc and peripapillary retina at age 12 years. The major retinal vessels remain visible, and pinpoint drusen are now visible on the surface of the disc. A fine network of filigree vessels overlies the optic disc. C, Fluorescein angiogram. Laminar phase shows patchy hyperfluorescence of the tumor with a lattice-like arteriovenous network of vessels overlying the disc. D, Fluorescein angiogram. Recirculation phase shows diffuse nodular staining of the tumor. E, Humphrey visual field testing shows isolated enlargement of the blind spot. F, Optical coherence tomography through the optic disc and macula shows an optic disc tuber extending into the subretinal space. Focal surface drusen on the disc produce focal shadowing within the tumor.
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At 12 years of age, her seizures were controlled with carbachol, and she was making excellent grades in school. Visual acuity was 20/20 OU. The patient was able to identify all Hardy-Rand-Ritter color plates using either eye. Both pupils responded briskly to light, and she retained a 1+ afferent pupillary defect in the right eye. Retinal examination disclosed circumferential enlargement of the optic disc tumor and increased smooth elevation of the peripapillary retina with no obscuration of the major retinal vessels (Figure B). Tiny surface drusen were now visible, and the optic disc was blanketed by a lattice-like arteriovenous network of filigree vessels. The left optic disc appeared normal.
Early-stage fluorescein angiography showed surface vascularity with mottled hyperfluorescence within the tumor (Figure C). The late-stage angiogram showed diffuse nodular staining of the tumor surface (Figure D). Visual field testing showed isolated blind spot enlargement with a normal mean deviation (Figure E). B-scan ultrasonography showed calcifications within the optic nerve head. Optical coherence tomography showed an intrinsic optic disc tumor extending into the peripapillary subretinal space, with surface drusen that produced shadowing within the tumor (Figure F).
Comment
In tuberous sclerosis, unilateral optic disc swelling is usually caused by an astrocytic hamartoma situated on the surface of the optic disc.3-4 The early lesion appears as a focal elevated mass of whitish, gray, or yellowish tissue that obscures visualization of the underlying retinal vessels.2 These optic disc phakomata may gradually calcify into raised tumors with a "mulberry-like" appearance that resembles optic disc drusen in consistency.2 Fluorescein angiography shows a prominent network of fine blood vessels in the superficial portion of the mass during the venous phase, and intense late staining of the tumor.3-4 Although these lesions only rarely enlarge,3-4 Shields et al5 recently documented visual loss secondary to massive enlargement of astrocytomas of the retina and optic disc in 4 patients with tuberous sclerosis.
Our patient's intrapapillary tumor was characterized by progressive enlargement of the optic disc, and gradual expansion into the peripapillary subretinal space, suggesting the possibility of a low-grade intrapapillary astrocytoma.5 Despite its impressive enlargement and increasing surface vascularity, this lesion has remained visually inconsequential during 10 years of observation.
AUTHOR INFORMATION
Correspondence: Dr Brodsky, Arkansas Children's Hospital, 800 Marshall St, Little Rock, AR 72202 (brodskymichaelc{at}uams.edu).
Financial Disclosure: None reported.
Funding/Support: This study was supported in part by an unrestricted grant from Research to Prevent Blindness.
REFERENCES
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1. Crino PB. Molecular pathogenesis of tuber formation in tuberous sclerosis complex. J Child Neurol. 2004;19:716-725.
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2. Brodsky MC, Baker RS, Hamed LM. Pediatric Neuro-Ophthalmology. New York, NY: Springer; 1996:405-407.3. Gass JDM. Stereoscopic Atlas of Macular Diseases: Diagnosis and Treatment. 4th ed. St Louis, Mo: Mosby; 1997:836-839.4. Shields JA. Retinal astrocytoma. In: Guyer DR, Yannuzzi LA, Chang S, Shields JA, Green WR, eds. Retina-Vitreous-Macula. Philadelphia, Pa: WB Saunders Co; 1999:1182-1187.5. Shields JA, Eagle RL, Shields CL, Marr BP. Aggressive retinal astrocytomas in 4 patients with tuberous sclerosis complex. Arch Ophthalmol. 2005;123:856-862.
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SECTION EDITOR: W. RICHARD GREEN, MD
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