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Central Retinal Vascular Obstruction Secondary to Melanocytoma of the Optic Disc
Jerry A. Shields, MD;
Carol L. Shields, MD;
Ralph C. Eagle, Jr, MD;
Arun D. Singh, MD;
Maria H. Berrocal, MD;
Jose A. Berrocal, MD
Arch Ophthalmol. 2001;119:129-133.
ABSTRACT
A 35-year-old black man developed abrupt visual loss in his left eye.
Ophthalmic examination revealed a deeply pigmented mass obscuring the optic
disc, hemorrhagic retinopathy, and signs of central retinal vascular obstruction.
Fluorescein angiography disclosed sluggish filling of the retinal blood vessels;
ultrasonography disclosed an acoustically solid mass in the optic nerve head.
Cytopathologic findings of a fine needle aspiration biopsy specimen demonstrated
probable benign tumor cells, but melanoma could not be excluded. Histopathologic
findings in the enucleated eye revealed a large, necrotic melanocytoma of
the optic disc and hemorrhagic necrosis of the retina secondary to obstruction
of the central retinal artery and vein. Melanocytoma of the optic nerve can
undergo spontaneous necrosis and induce central retinal vascular obstruction.
Abrupt visual loss in a patient with a melanocytoma does not necessarily imply
malignant transformation.
INTRODUCTION
Melanocytoma is a variant of melanocytic nevus that is most often recognized
on the optic disc but can occur anywhere in the uveal tract.1-6
Most cases that occur on the optic disc are visually asymptomatic, but they
can cause an afferent pupillary defect and a visual field defect.7-8 Although melanocytoma of the optic
nerve rarely can cause visual loss when the tumor becomes necrotic, associated
central retinal vascular obstruction is rare. We report a clinicopathologic
correlation of a necrotic optic disc melanocytoma that caused a central retinal
vascular obstruction and hemorrhagic retinopathy.
REPORT OF A CASE
A healthy 35-year-old black man noticed painless, progressive visual
loss in the left eye for 1 week. He was found to have an optic nerve mass
and retinal hemorrhages and was referred to the Ocular Oncology Service at
Wills Eye Hospital, Philadelphia, Pa, for further evaluation and management
of this condition. His medical history was otherwise noncontributory and he
did not recall having a prior fundus examination. His visual acuity was 20/20
OD and hand movements OS. The left pupil was slightly dilated and there was
a left afferent pupillary defect. Intraocular pressure was 21 mm Hg OU. Anterior
segment examination showed scattered cells in the anterior chamber and anterior
vitreous of the left eye. There was no iris neovascularization. The fundus
of the right eye was normal and the pertinent findings were in the left fundus.
The left optic disc was obscured by a black mass that measured 5 x
5 mm in diameter (Figure 1). The
retinal vessels were dilated and tortuous and the entire fundus posterior
to the equator contained numerous superficial and deep retinal hemorrhages.
A localized hemorrhagic retinal detachment extended from the optic nerve inferonasally.
Many of the retinal vessels appeared white.
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Figure 1. Fundus photograph showing pigmented
mass over optic disc.
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Fluorescein angiography demonstrated delayed flow through the retinal
arteries and veins with hypofluorescence of the retinal hemorrhages. The black
mass overlying the optic disc remained hypofluorescent throughout the angiogram
(Figure 2). There was widespread
vascular leakage and diffuse staining of the sensory retina in the late frames.
Using ultrasonography, the lesion showed high internal reflectivity with A-scan
and acoustic solidity with B-scan and measured 3 mm in thickness (Figure 3). Magnetic resonance imaging of
the orbits demonstrated a small, elevated lesion at the level of the optic
disc with 2 to 3 mm of increased enhancement in the optic nerve posterior
to the globe (Figure 4). The lesion
was slightly hyperintense to vitreous on T1-weighted images and markedly hypointense
to vitreous on T2-weighted images. There was only minimal evidence of tumor
in the optic nerve posterior to the lamina cribrosa. The patient underwent
a systemic evaluation for neoplastic, vascular, and inflammatory diseases
including a chest x-ray film, angiotensin-converting enzyme levels, and sickle
cell preparation, all results of which were normal or negative.
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Figure 2. Fluorescein angiogram taken 71
seconds after injection showing hypofluorescence of the mass, normal choroidal
fluorescence, but very minimal flow in the retinal blood vessels.
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Figure 3. B-scan ultrasonogram showing elevated
mass over the optic disc.
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Figure 4. Contrast-enhanced, coronal magnetic
resonance imaging through anterior orbit immediately posterior to the globe,
showing increased enhancement of the right optic nerve (arrow).
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Our clinical diagnoses were melanocytoma of the optic disc, secondary
obstruction of the central retinal artery and vein, and hemorrhagic retinopathy.
However, less likely possibilities, including a necrotic melanoma of the optic
disc or a neoplasm of the retinal pigment epithelium could not be excluded
on clinical grounds.
The options of observation, enucleation, or diagnostic fine-needle aspiration
biopsy (FNAB) were discussed with the patient and he elected to have FNAB
prior to making a definitive therapeutic decision. Fine-needle aspiration
biopsy was performed through the pars plana of the ciliary body with a transvitreal
route and indirect ophthalmoscopic guidance using a published technique.9 Cytopathologic studies demonstrated numerous benign-appearing
cells that contained abundant cytoplasmic melanin (Figure 5). An experienced cytopathologist believed that the cells
were more suggestive of adenoma or adenocarcinoma of the retinal pigment epithelium
rather than melanocytoma or melanoma. However, melanoma could not be absolutely
excluded.
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Figure 5. Cytologic features of fine needle
aspiration biopsy, showing clump of cells with moderately large nuclei and
cytoplasmic melanin (Papanicolaou, original magnification x300).
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The patient was informed of the poor visual prognosis and the possibility
of malignancy and he elected to undergo enucleation. This was performed without
complication, taking care to obtain a long section of optic nerve with the
globe.
Gross histopathologic examination of the eye before sectioning showed
a normal globe with 18 mm of optic nerve attached. The globe did not permit
transillumination, due to racial pigmentation. Gross examination of the sectioned
globe revealed a pigmented epipapillary mass measuring 4 x 4 x
3 mm and causing elevation of the circumpapillary retina. There were numerous
superficial and deep retinal hemorrhages from the posterior fundus to the
equatorial region.
Microscopic examination revealed scattered polymorphonuclear leukocytes,
some of which had been ingested by macrophages, in the anterior chamber inferiorly.
The lens was normal. The vitreous was detached posteriorly and contained small
foci of blood. The optic disc and anterior portion of the optic nerve were
replaced by an intensely pigmented and largely necrotic tumor that extended
into the optic nerve posterior to the lamina cribrosa (Figure 6). Bleached sections revealed that the residual viable tumor
cells had a low nuclear-cytoplasmic ratio and bland nuclei (Figure 7). Surprisingly, some cells contained a prominent population
of large round melanosomes, including some macromelanosomes, that persisted
in the bleached sections. The tumor extended slightly into the peripapillary
choroid and sensory retina. The adjacent choroid and retina were necrotic
and contained extensive hemorrhage. The retinal blood vessels were markedly
dilated and congested. Polymorphonuclear leukocytes filled the lumen of a
large thick-walled blood vessel in the optic nerve head, presumably the central
retinal artery. The optic nerve posterior to the tumor showed widening of
the pial septae and increased cellularity consistent with gliosis. Cross sections
of the surgical margin of the optic nerve showed no evidence of tumor.
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Figure 6. Low-power magnification photomicrograph
showing deeply pigmented mass involving the retrolaminar and prelaminar portions
of optic nerve and the juxtapapillary retina and choroid (hematoxylin-eosin,
original magnification x5).
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Figure 7. Photomicrograph of bleached section
of tumor in an area of viable tumor cells. The nuclei are bland and the nuclear
cytoplasmic ratio is low (original magnification x250).
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The final diagnoses were as follows: (1) necrotic melanocytoma; (2)
central retinal artery and vein obstruction secondary to necrotic melanocytoma;
(3) hemorrhagic infarction of the retina secondary to central retinal artery
and vein obstructions; (4) serosanguineous retinal detachment; (5) juxtapapillary
choroidal necrosis and inflammation; (6) optic nerve atrophy; and (7) small
hypopyon.
COMMENT
Melanocytoma of the optic disc is a benign melanocytic tumor that rarely
causes visual impairment.1-4
However, this tumor has a tendency to undergo necrosis, particularly when
located in the iris, where necrotic tumor cells and macrophages can cause
reduction of aqueous outflow and secondary glaucoma.10-11
Although the visual loss is usually permanent, it has rarely been known to
improve after the necrotic episode.12
When a pigmented fundus lesion is associated with severe visual loss,
it is tempting to attribute the visual impairment to malignant transformation.
However, well-documented cases of malignant transformation of optic disc melanocytoma
are rare.13-14 When visual loss
occurs in an eye with a melanocytoma, it is more likely to be due to necrosis
of the benign tumor rather than malignant transformation. The necrosis of
the tumor within the optic nerve causes loss of optic nerve function and visual
impairment. Although the sequence of events is not entirely clear, it is possible
that the tumor causes vascular obstruction which, in turn, leads to necrosis
in the tumor.15
In rare instances, a necrotic optic disc melanocytoma can also cause
obstruction of the central retinal vessels, as occurred in our patient. We
are aware of 2 other cases of retinal vascular obstruction secondary to a
melanocytoma of the optic nerve. In his series of optic nerve melanocytomas,
Zimmerman2 reported the histopathologic findings
in a case in which a necrotic tumor had caused a central retinal artery obstruction.
Croxatto et al15 described a patient with a
melanocytoma of the optic disc that caused retinal vaso-occlusive disease
that led to neovascular glaucoma, requiring enucleation.
In our patient, it appears that the highly necrotic melanocytoma caused
a combined central retinal artery and vein obstruction, as demonstrated with
fluorescein angiography that disclosed minimal blood flow through the retinal
vessels. It is quite possible that our patient also would have developed neovascular
glaucoma had the eye not been enucleated.
Fine-needle aspiration biopsy is a generally reliable method for diagnosing
intraocular tumors and pseudotumors in difficult cases. However, in some instances,
it may be difficult to differentiate cytopathologically a melanoma, melanocytoma,
and adenoma of the retinal pigment epithelium. In this case, the diagnosis
of melanoma could not be excluded on the basis of cytopathologic findings
from the FNAB, underscoring the limitations of that technique. Enucleation
was justified in this case because melanoma was a possibility and the affected
eye had minimal visual potential. This case demonstrates that an optic nerve
melanocytoma can undergo necrosis and cause obstruction of the central retinal
vessels and severe visual loss. Visual loss in a patient with an optic nerve
melanocytoma does not necessarily mean that the tumor has undergone malignant
transformation.
AUTHOR INFORMATION
Accepted for publication March 24, 2000.
This investigation was supported by the Eye Tumor Research Foundation,
Philadelphia, Pa, the Award of Merit in Retina Research, Houston, Tex (Dr
J. A. Shields), the Macula Foundation, New York, NY (Dr C. L. Shields), and
the Noel T. and Sara L. Simmonds Endowment for Ophthalmic Pathology, Wills
Eye Hospital, Philadelphia (Dr Eagle).
Presented at the Eastern Ophthalmic Pathology Society, Orlando, Fla,
October 21, 1999, and the Fluorescein Club, Orlando, Fla, October 24, 1999.
Reprints: Jerry A. Shields, MD, Oncology Service, Wills Eye Hospital,
Thomas Jefferson University, 900 Walnut St, Philadelphia, PA 19107.
From the Ocular Oncology Service (Drs J. A. Shields, C. L. Shields,
and Singh) and the Department of Pathology (Dr Eagle), Wills Eye Hospital,
Thomas Jefferson University, Philadelphia, Pa; and the Department of Ophthalmology,
University of Puerto Rico, San Juan (Drs M. H. Berrocal and J. A. Berrocal).
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