Distinguishing Choroidal Nevi from Melanomas Using the MOLES Algorithm: Evaluation in an Ocular Nevus Clinic

Real-world experience of implementing the MOLES score in a virtual choroidal naevi clinic at a tertiary referral centre

INTRODUCTION

The MOLES score has been validated to clinically differentiate choroidal naevi from melanomas by ocular oncologists and community optometrists. However, its utility in a virtual choroidal naevi clinic at a tertiary eye hospital without specialist ocular oncology services has not yet been evaluated.

METHODS

A retrospective case review of 385 choroidal lesions in the virtual choroidal naevus clinic at Bristol Eye Hospital during January-March 2020 and April-August 2021 was performed. Choroidal lesions were assessed using the TFSOM-UHHD risk factor index and MOLES score, respectively. For both study periods, clinical outcome and adherence data were analysed.

RESULTS

Choroidal lesions scored higher with the TFSOM-UHHD index (median 2) compared to the MOLES score (median 0; p < 0.001). Median required follow-up duration was 2 years for lesions assessed with the TFSOM-UHHD index, and 0 years for those graded with the MOLES score. Overall, 215 patients were appropriately discharged to community optometrists based on their MOLES score. Imaging requirements for the TFSOM-UHHD index and MOLES score protocols were met in 69.1% and 94.8% of cases, respectively.

CONCLUSION

The MOLES score was easily implemented in a virtual choroidal naevus clinic, with good adherence. It increased clinic capacity by facilitating appropriate discharges of low-risk naevi to community monitoring, allowing finite and specialist hospital-based services to monitor higher-risk naevi more closely.

Choroidal Nevus Features Associated with Subspecialty Referral

OBJECTIVE

To identify choroidal nevus features associated with referral to a retina or ocular oncology subspecialist.

DESIGN

Population-based retrospective cohort study.

SUBJECTS

Patients diagnosed with choroidal nevus.

METHODS

Population-based retrospective cohort study of residents of Olmsted County, Minnesota, with an incident diagnosis of choroidal nevus from January 1, 2006, to December 31, 2015 using the Rochester Epidemiology Project, a medical record linkage system. Tumor features and patient demographics associated with referral to a retina or ocular oncology subspecialist were assessed. Wilcoxon rank sum test, chi-square test, and Fisher exact test were used for statistical analysis.

MAIN OUTCOME MEASURES

Tumor features and patient demographics associated with referral to subspecialty care.

RESULTS

There were 826 incident diagnoses of choroidal nevus, of which 88 cases (11%) were referred, with highest level of referral being retina in 29 cases (33%) and ocular oncology in 59 cases (67%). None of the analyzed demographic features were associated with choroidal nevus referral to subspecialty care. Tumor features associated with referral (vs. not referred) included greater mean basal diameter (4.6 mm vs. 2.4 mm, P < 0.001), greater mean tumor thickness (0.7 mm vs. 0.1 mm, P < 0.001), greater distance to optic disc (6.9 mm vs. 3.4 mm, P = 0.02), halo around nevus (5.7% vs. 0.4%, P < 0.001), and drusen on OCT (51% vs. 25%, P = 0.002). Presence of orange pigment (8% vs. 0%, P = 0.14), subretinal fluid (9% vs. 2.5%, P = 0.09), and low internal reflectivity on A-scan (7.7% vs. 0%, P = 1.00) were not found more frequently in the subspecialty referral group.

CONCLUSIONS

Greater basal diameter and mean tumor thickness of choroidal nevus were associated with referral to retina or ocular oncology. However, several features associated with increased risk of malignant transformation were not associated with subspecialty referral. These findings highlight the importance of educating eye care providers about high-risk tumor features associated with choroidal nevus transformation to melanoma. In the primary eye care setting where not all multimodal imaging may be available, we encourage color photography and OCT with referral for any features of basal diameter > 5 mm, presence of subretinal fluid, or thickness too large for capture by enhanced-depth imaging OCT.

FINANCIAL DISCLOSURE(S)

The authors have no proprietary or commercial interest in any materials discussed in this article.

Is Tumour Thickness Measurement Required for MOLES Scoring of Melanocytic Choroidal Tumours?

Introduction

It can be challenging to distinguish between choroidal naevi and melanomas in the community setting, particularly without access to ultrasonography (US), required to measure the thickness of melanocytic choroidal tumours. We aimed to determine whether thickness measurement is required for MOLES scoring of melanocytic choroidal tumours.

Methods

The dataset of a recent MOLES evaluation was reviewed. Patients were selected for the present study if their MOLES tumour size category was determined by tumour thickness measured with US. The largest basal tumour diameter and tumour thickness were then measured from ultra-widefield fundus images and optical coherence tomography (OCT) images, respectively.

Results

The tumour size category was determined by tumour diameter in 203/222 (91.4%) with no influence of tumour thickness. The tumour thickness influenced the MOLES score in 19/222 (8.6%) patients. In 11/19 patients with OCT measurements of tumour thickness, the US measurement exceeded the OCT by more than 25% in 5 patients, more than 50% in 2 patients, and more than 75% in 1 patient. As a result, the revised tumour thickness based on OCT determined the size category in 4/216 (1.8%) patients. The ultra-widefield fundus images measurements increased the diameter score by 1 in 5 patients. As a result, the revised tumour thickness determined the size category in 4/216 (1.8%) patients. If both the revised diameter and thickness scores were considered, the MOLES score reduced in 4 patients. If both the diameter and thickness scores were considered, the MOLES score reduced in 5 and increased in 1. Only 0.94% (2/211) of melanocytic choroidal tumours assessed with MOLES when using Optos ultra-widefield fundus images diameter and OCT to measure tumour diameter and thickness, respectively, required a change in management from a reduction in MOLES score from 1 to 0.

Discussion/Conclusion

This study suggests that the MOLES category for size is influenced more by the tumour diameter, if it can be measured accurately, than by the thickness. This study suggests ignoring tumour thickness if this cannot be measured accurately with OCT, unless the tumour has a mushroom shape.

Can the MOLES acronym and scoring system improve the management of patients with melanocytic choroidal tumours?

It can be difficult for practitioners to determine the likelihood of malignancy in melanocytic choroidal tumours. This author has therefore devised the MOLES acronym to highlight the most informative clinical features, which comprise mushroom shape, orange pigment, large size, enlargement, and subretinal fluid. Each of these is scored 0 if absent, 1 if subtle or uncertain, and 2 if present. Tumours are categorised as ‘common naevus’, ‘low-risk naevus’, ‘high-risk naevus’ and ‘probable melanoma’ according to whether the sum of these five scores is 0, 1, 2 or 3 or more, respectively. Tentative recommendations, subject to future studies, include: review of ‘common naevi’ by a community optometrist whenever the patient attends for another reason, such as a two-yearly ‘check-up’ (i.e., ‘self-care’); non-urgent referral of patients with ‘low-risk naevi’ or ‘high-risk naevi’ to an ophthalmologist to plan long-term surveillance (i.e., determining the frequency of assessments and whether these should be undertaken by an ophthalmologist or a community optometrist); and urgent referral of patients with a MOLES score >2 (i.e., ‘probable melanoma’) to an ophthalmologist for immediate referral to an ocular oncologist if a suspicion of malignancy is confirmed. The MOLES system does not require assessment of internal acoustic reflectivity by ultrasonography. MOLES scores correlate well with diagnosis of choroidal naevi and melanomas by ocular oncologists; however, further evaluation of this aid in routine optometric practice and other situations is needed. MOLES should prevent unnecessary referral of patients with naevi for second opinion and non-essential monitoring of these patients at hospital eye services.

Assessing Choroidal Nevi, Melanomas and Indeterminate Melanocytic Lesions Using Multimodal Imaging—A Retrospective Chart Review

Using multimodal imaging, the literature proposed the following risk factors for choroidal nevus growth into melanoma: increased tumor thickness, subretinal fluid, decreased visual acuity, presence of orange pigment, ultrasound acoustic hollowness, and increased tumor diameter. This study investigated the presence of the mentioned risk factors in choroidal nevi, choroidal melanomas, and indeterminate choroidal melanocytic lesions. This retrospective, single-center chart review assessed choroidal melanocytic tumors with multimodal imaging. We defined our primary outcome as the cumulative presence of mentioned risk factors. Further, we evaluated various optical coherence tomography (OCT), ultrasound, and autofluorescence findings. We analyzed 51 tumors from 49 patients during the period from April 2008 to June 2021. The median (IQR) age was 64.0 (56.0 to 70.5) years, with 23 of 49 (46.9%) patients being female. The follow-up time for all tumors was median (IQR) 25.0 (12.0 to 39.0) months. The choroidal nevi had a median (range) risk score of 0.0 (0.0 to 3.0), and the choroidal melanoma of 5.0 (3.0 to 6.0), with statistically significant different ratings (p < 0.001). Multimodal imaging creates a score that may help to distinguish choroidal nevi from choroidal melanomas objectively.

Reply to Comment on Roelofs, K.A.; et al. "Detecting Progression of Melanocytic Choroidal Tumours by Sequential Imaging: Is Ultrasonography Necessary?" Cancers 2020, 12, 1856

We thank Capasso et al [...].