Differentiation of a choroidal nevus from a small choroidal melanomacan be difficult. Choroidal nevi are generally asymptomatic lesions1 that are less than 6 mm in diameter and less than1.5 mm in height. The presence of drusen or areas of atrophy of the overlyingretinal pigment epithelium generally indicate a chronic, inactive choroidalnevus.1 Orange pigment and subretinal fluidare more commonly present in choroidal melanomas.2 Echographyusually demonstrates medium to high internal reflectivity in nevi and lowreflectivity in melanomas. Documented growth3,4 iswidely interpreted as evidence of malignancy.
We provide the histopathology of 2 small choroidal melanocytic tumorsthat became symptomatic, developed orange pigment, and showed documented growth.One lesion was an epithelioid malignant melanoma; the other was a benign nevus.
A 45-year-old man was examined in May 1996 at the Ocular Oncology Clinicof the University of Michigan Kellogg Eye Center, Ann Arbor, for an enlarging,small juxtapapillary choroidal lesion in his right eye. A photograph from1994 (Figure 1) showed a flat, brown3.0 × 1.8-mm choroidal lesion, superior to the disc, withoutdrusen or orange pigment. The lesion had increased to 3.0 × 3.0mm and developed extensive orange pigment over its surface. Echography revealeda maximal height of 1.5 mm with a medium internal acoustic pattern. The initialdiagnosis was a probable melanoma, but a decision was made to observe forevidence of continued growth before initiating therapy. In July 1996, thepatient complained of blurred vision in his right eye. Results of an examinationshowed that the base had further increased to 3.3 × 3.2 mm(Figure 2). Repeat echography revealedthat tumor height had increased to 1.7 mm. The patient was advised that thelesion was malignant. He subsequently underwent an unremarkable evaluationfor metastatic disease. After reviewing possible options, the patient decidedto have his eye removed.
Fundus photograph of the right eyeof case 1 shows a flat, pigmented choroidal lesion superior to the disc.
Fundus photograph of the right eyeof case 1 shows a symptomatic, enlarged choroidal lesion 2 years after thephotograph in Figure 1.
A 47-year-old man was examined in April 1995 in the Ocular OncologyClinic for an enlarging, small pigmented choroidal mass beneath his left macula.A photograph from March 1991 (Figure 3)showed a flat, pigmented 4.3 × 3.2-mm lesion beneath the inferiormacula. The lesion had no drusen, orange pigment, or adjacent subretinal fluid.The lesion had increased to 6.0 × 4.0 mm and had focal orangepigment over the surface of the lesion. Echography revealed a maximum heightof 2.0 mm with medium internal reflectivity. Because the growth had occurredover a 4-year period, the initial decision was to follow the lesion. In February1996, the patient complained of constant flickering in the central aspectof his left visual field. The lesion now showed increased orange pigmentation,and the base had increased to 6.5 × 4.5 mm (Figure 4). Repeat echography showed that the internal acoustic patternand height were unchanged. The patient was advised that the lesion showedevidence of malignancy and underwent a metastatic evaluation, which was unremarkable.After reviewing possible options, the patient elected to have his eye removed.
Fundus photograph of the left eyeof case 2 shows a flat, pigmented choroidal lesion beneath the inferior macula.
Fundus photograph of the left eyeof case 2 five years later shows a clinically symptomatic, enlarged pigmentedchoroidal lesion beneath the inferior macula.
Histopathological examination of the right eye of patient 1 (Figure 5) showed a epithelioid cell–typemalignant melanoma of the choroid, arising from a preexisting nevus.
Cross section of the peripapillarychoroidal tumor of case 1 shows an epithelioid cell–type malignant melanoma(hematoxylin-eosin, original magnification ×100).
Histopathological examination of the left eye of patient 2 (Figure 6) showed a benign spindle nevus of thechoroid with numerous melanophages within the lesion. Multiple histopathologicalsections through various portions of the tumor failed to show any evidenceof melanoma. The clinically apparent orange pigment of the tumor appearedto correlate with the presence of melanophages.
Cross section of the central aspectof the macular tumor of case 2 shows a benign spindle nevus of choroid withscattered melanophages within the lesion (hematoxylin-eosin, original magnification×100).
In the Collaborative Ocular Melanoma Study,5 histopathologicalexamination of 413 eyes with a clinical diagnosis of choroidal melanoma demonstrateda misdiagnosis rate of 0.48%. In contrast to our cases, however, all of thosetumors had a height of greater than 2.5 mm. With lesions less than 2 mm inheight, it is more difficult to distinguish a nevus from a melanoma.
Recent studies6- 8 havedocumented that certain clinical features are predictive of growth of smallmelanocytic choroidal tumors. These features include visual symptoms, greatertumor thickness and diameter, presence of orange pigment, absence of drusen,absence of retinal pigment epithelial changes adjacent to the tumor, posteriortumor margin adjacent to the disc, and subretinal fluid. In those studies,growth was presumed to be the key indicator of malignant transformation, asthose small lesions were generally treated with globe-preserving therapieswith no histopathological confirmation of the malignancy.
The 2 lesions described in this report exhibited many of the clinicalfeatures predictive of growth and documented growth, but only one of the lesionswas malignant. With the exception of one feature, posterior margin adjacentto the disc, the benign choroidal nevus demonstrated the same array of predictivefactors for growth8 as the malignant melanomadid. Moreover, the nevus showed the greater growth in height (2.0 mm vs 1.7mm), but over a longer period (5 years vs 2 years). On a clinical basis, itwas not possible to distinguish this enlarging nevus from a growing melanoma.
Augsburger and colleagues9 have advocatedthe use of transvitreal biopsy of small melanocytic choroidal tumors to achievean accurate diagnosis. With their technique, they were able to obtain a sufficientaspirate for cytodiagnosis in 65% of cases, but in 18% of those cases, thebiopsy specimen showed intermediate cells consistent with either atypicalnevus or low-grade melanoma.
Growth or enlargement of choroidal nevi has been previously documented.1,10 Our report demonstrates that documentedgrowth is not an unequivocal indicator of melanoma for small melanocytic tumors.
Correspondence: Dr Vine, University of MichiganKellogg Eye Center, 1000 Wall St, Ann Arbor, MI 48105 (email@example.com).
Financial Disclosure: None.
Elner VM, Flint A, Vine AK. Histopathology of Documented Growth in Small Melanocytic ChoroidalTumors. Arch Ophthalmol. 2004;122(12):1876-1878. doi:10.1001/archopht.122.12.1876