New protocols and technological processes may offer advanced characterization for choroidal nevus

This case involves a White patient who came from another practice where she was told that she had a freckle in one of her eyes. She came for a visit after telling her daughter, who was a staff member at the clinic, of the diagnosis. At the time of her baseline visit, she was 62 years old.

She was in good health, was taking no medications, and was free from significant medical history. Significant in her ophthalmic history was the diagnosis of a pigmented lesion in her left eye. In addition, she denied using illicit drugs. She is a lifelong nonsmoker but admitted to social alcohol use.

Figure 1. Color fundus photograph at baseline.The distinct borders of the slate-gray lesion are evident and even more distinct at clinical examination. The lesion itself extends just temporal to the retinal venule exiting the optic disc superiorly (broad arrow).

Ophthalmic evaluation showed visual acuity correctable to 20/20 in each eye. She was visually asymptomatic for flashes, floaters, and pain. Ocular alignment was straight, pupillary reactions were normal without relative afferent pupillary defect (RAPD), and visual fields were full to finger counting (FTFC). Applanation tonometry was measured at 16 mm Hg in each eye. Slit lamp examination of each eye determined that the anterior segments were age appropriate in each eye. Evaluation of the ocular fundus through a dilated pupil showed the pigmented lesion in her right eye (Figure 1). The media are relatively clear. The course and caliber of the retinal vasculature are appropriate. The disc margins are distinct.

Attention is drawn to the pigmented lesion and its overlying drusen superior and slightly nasal to the optic disc. Stereoscopic examination revealed a flat lesion without margins abutting the optic disc. The closest proximity to the optic disc is less than 3 mm. The estimated greatest diameter was less than 3 mm (based on an optic disc diameter of 1.7 mm). The baseline color fundus photograph was complemented by a clinical view modified by red-free filtered light. It demonstrated attenuation of the intensity of the melanin pigmentation of the lesion. Fundus evaluation of the fellow eye was unremarkable. Given this clinical presentation, a diagnosis of choroidal nevus was made.1-6 The patient was educated regarding the nature of the freckle that she had been appraised of by her previous physician. She was asked to return for evaluation and documentation in 1 year.

At the 1-year follow-up visit, the ophthalmic and medical histories were unchanged. Her visual acuity was correctable to 20/20 in each eye, and she remained neurologically intact (negative result for RAPD, straight ocular alignment, FTFC visual fields, symmetrical lid position). Clinical appearance of the lesion was unchanged compared with the documented baseline appearance. No photographic documentation was ordered. Because the lesion remained flat, further testing was not ordered. Fundus evaluation of the fellow eye remained unremarkable. The patient was reassured and again asked to return in a year.

At her next follow-up visits, the ophthalmic and medical histories remained unchanged (Figures 2-4). Her visual acuity continued to be correctable to 20/20 in each eye, and she remained neurologically intact (negative result for RAPD, straight ocular alignment, FTFC visual fields, symmetrical lid position). The most recent clinical appearance of the lesion is illustrated in Figure 5. Fundus evaluation of the fellow eye continued to be unremarkable. The patient was reassured and again asked to return for monitoring in 1 year. Because of personal circumstances, she did not return to care and was subsequently lost to follow-up.

Discussion

Although the differential diagnosis of pigmented fundus lesions is limited, the distinctions among these lesions can be daunting, especially when the presentation is one that is prominent in the posterior pole, as in the present case. Clues in this case are numerous. The patient reported that a previous physician had educated her about a freckle. The clinical appearance and color fundus photograph demonstrated a slate-gray color to the lesion, which was limited in dimension, and there were drusen on the surface. All these features are characteristic of choroidal nevus.^1-6 With the exception of being located within 3 mm of the optic disc, none of these would be remotely suggestive of suspicious choroidal nevus.⁶

The evolution of terminology and guidance based on clinical factors began with published studies from the Armed Forces Institute of Pathology. As the name of the institution implies, these studies included eyes that were enucleated with a clinical diagnosis of malignant melanoma. The lack of clarity was highlighted by 2 publications in the early 1980s.^7,8 Each of these reports cited suspicious choroidal nevus or lesions of the retinal pigment epithelium to describe the simulating lesions. These pseudomelanomas were reported to occur in 20% to 27% of cases described clinically as malignant melanoma. But this climbed to 49%, likely because of increased clinician awareness and improved evaluation technology, in a clinical report consisting of patients seen between 1978 and 2003.⁹

From detailed prospective and retrospective data analysis, a useful mnemonic was developed for assisting clinicians in distinguishing between small choroidal melanoma and nevus, benign melanocytic presentation. The first of these came from the Wills Eye Hospital in Philadelphia, Pennsylvania, which is TFSOM. This cleverly represents the phrase to find small ocular melanoma as well as the clinical attributes of small choroidal melanomas, namely T (thickness > 2 mm), F (subretinal fluid), S (symptoms: reduced vision, flashes/floaters), O (orange pigment), and M (margin touching optic disc).^5,7 Patients with 3 of these features are likely to have melanoma.⁵

More recent data have been used to amplify the original mnemonic. The updated one is TFSOM-UHHD (where UHHD designates using helpful hints daily, corresponding to U (ultrasound), H (hollow), H (halo absent), and D (drusen absent). In addition, the geographic location of the margin was relocated to less than 3 mm from the optic disc rather than adjacent to it as originally established.⁶

An attempt to develop a standardized protocol for distinguishing choroidal nevus and melanoma has been reported and validated from data gathered through Australia’s National Eye Health Survey.^1,2 These investigators use the mnemonic MOLES, corresponding to M (mushroom shape), O (orange pigment), L (large size [> 1.7-mm diameter]), E (enlargement over the observation period), and S (subretinal fluid). Note that there is overlap and some deviation from the American system of TFSOM. The size difference is the most striking between the 2 systems.

The epidemiology of choroidal nevus has been consistent within a narrow range of prevalence: between 4% to 8% in White individuals over decades.^3,4,7,10-12 The conversion of nevus to melanoma is extremely rare, with few examples cited in the literature.^10,13-15

Improvement in the characterization of choroidal nevi and assessment of risk for conversion to melanoma have changed the paradigm of management based on clinical observation and useful mnemonics. Going forward, clinicians can apply advanced imaging modalities to minimize the misdiagnosis of simulating lesions (pseudomelanomas). These technologies go beyond stereoscopic fundus examination and photographic documentation with review. Although color fundus photography is highly sensitive for correctly identifying choroidal nevi, other modalities may enhance that accuracy.¹⁶ Enhanced-depth optical coherence tomography (OCT) imaging, confocal infrared imaging, and even OCT angiography are a few examples of emerging methodologies for characterizing accurately pigmented lesion of the choroid.^16-22 In addition, artificial intelligence may have a role in augmenting clinical findings.²³

The present case is in alignment with the diagnosis and contemporary management of choroidal nevus. These benign cases should be monitored safely but not ignored.

References

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