CYTOGENETIC TESTING OF IRIS MELANOMA USING FINE NEEDLE ASPIRATION BIOPSY IN 17 PATIENTS

Iris melanoma: Prognostication for metastasis

Uveal melanoma prognostication studies have mainly included posterior uveal melanomas located in the ciliary body and choroid, often excluding iris melanoma. In this study, we report prognostic status and survival outcomes in a series of 35 patients with biopsy-proven iris melanoma. Fluorescence in situ hybridization was performed in 10 (29%) cases and 2 (5%) underwent multiplex ligation-dependent probe amplification. In total, 9 cases demonstrated disomy 3, 2 cases with monosomy 3 (fluorescence in situ hybridization), and 1 had a technical failure. On gene expression profile testing, 20 of the 23 cases (90%) were gene expression profile class 1A, and the remaining 3 (10%) were class 1B. No patient had a Class 2 status. The median follow-up period was 49 months (mean 59, range 2-156 months). No metastasis was reported during follow-up, and metastasis-free survival was 100%. A review of the published literature revealed 47 cases with high-risk status on molecular prediction, of which only 6 (13%) developed metastasis. Ciliary body involvement was reported in 5 cases and was unknown in 2 cases. We conclude that molecular prognostication of iris melanoma demonstrates low-risk prognostic status in the majority of cases irrespective of the technique used. Even those with high-risk status do not develop metastasis unless the tumor involves the ciliary body.

Iris melanocytic tumours in New Zealand/Aotearoa: presentation, management and outcome in a high UV exposure environment

BACKGROUND/OBJECTIVES

Iris melanoma, a rare intraocular malignancy, represents the smallest subgroup of uveal melanoma. This first, comprehensive study of iris melanocytic lesions in the high ultraviolet environment in New Zealand/ Aotearoa (NZ) examines diagnosis, management and outcomes.

SUBJECTS/METHODS

Retrospective study of iris melanocytic tumours referred to tertiary referral centres in Auckland, NZ, over 20 years (1999-2018). Data analysed include demographics, tumour characteristics, histology, genetic analyses, treatment modalities, recurrence, metastasis, 5-year and overall survival.

RESULTS

Cohort (N = 51) was predominantly NZ European (98.0%) with no indigenous Māori, or Pasifika. Median age at presentation was 58 years. Tumours involved a median of two clock hours of iris. The posterior tumour margin extended to the anterior chamber angle in 22 patients (45.8%). Management included initial observation 54.9%, iridectomy/excision biopsy 29.4%, irido-cyclectomy 7.8%, plaque radiotherapy 7.8%, proton beam radiotherapy 7.8%, and ultimately enucleation 17.6%. Histology was performed in 19 cases (37%) with 16 confirmed melanomas (84%). Mean follow-up 4.2 years with median visual acuity of 6/7.5 two years post intervention. Melanoma-related metastasis and mortality occurred in two cases with five-year melanoma-related mortality of 2.0%.

CONCLUSION

In a climate with high ultraviolet exposure iris melanocytic tumours occurred almost exclusively in NZ Europeans, however, the majority of cases were category T1, possibly reflecting early diagnosis in the NZ health system. Nonetheless, >50% underwent surgery or radiotherapy, often utilising more than one modality. A high index of suspicion and early referral of iris melanocytic lesions should be considered in regions with high UV exposure.

Iris melanoma outcomes based on the Cancer Genome Atlas (TCGA) classification in 78 consecutive patients

BACKGROUND

The Cancer Genome Atlas (TCGA) classification of genetic alterations in uveal melanoma is widely used for prognostication. We present novel observations on the impact of TCGA Group specifically for iris melanoma.

METHODS

This was a retrospective cohort study at a tertiary referral ocular oncology center. All patients with a diagnosis of iris melanoma who underwent genetic evaluation and assessment for TCGA classification between 20 November 1995 and 5 April 2021 were included. The main outcome measures were visual acuity, secondary glaucoma, tumor recurrence, melanoma-related metastasis and death per TCGA group.

RESULTS

There were a total of 78 patients included. The mean patient age was 49.6 years (median 53.0, range 3.0-85.0), mean tumor basal diameter was 6.7 mm (median 6.0, range 1.5-22.0), and mean tumor thickness was 2.6 mm (median 2.5, range 0.5-8.5). Cytology results confirmed iris melanoma (93%) or were inconclusive (7%). The TCGA groups included Group A (n = 36, 46%), Group B (n = 7, 9%), Group C (n = 34, 44%), and Group D (n = 1, 1%). There was no statistically significant difference in outcomes of visual acuity, tumor thickness reduction, secondary glaucoma, tumor recurrence, melanoma-related metastasis or death per individual TCGA group (A vs. B vs. C vs. D) and per bimodal comparison (A/B vs. C/D).

CONCLUSIONS

In this analysis, iris melanoma was classified as TCGA group A or B in 55% and as C or D in 45%. The TCGA classification was not predictive of melanoma-related metastasis or death.

Causes, consequences and clinical significance of aneuploidy across melanoma subtypes

Aneuploidy, the state of the cell in which the number of whole chromosomes or chromosome arms becomes imbalanced, has been recognized as playing a pivotal role in tumor evolution for over 100 years. In melanoma, the extent of aneuploidy, as well as the chromosomal regions that are affected differ across subtypes, indicative of distinct drivers of disease. Multiple studies have suggested a role for aneuploidy in diagnosis and prognosis of melanomas, as well as in the context of immunotherapy response. A number of key constituents of the cell cycle have been implicated in aneuploidy acquisition in melanoma, including several driver mutations. Here, we review the state of the art on aneuploidy in different melanoma subtypes, discuss the potential drivers, mechanisms underlying aneuploidy acquisition as well as its value in patient diagnosis, prognosis and response to immunotherapy treatment.

Genetic drivers of non-cutaneous melanomas: Challenges and opportunities in a heterogeneous landscape

Non-cutaneous melanomas most frequently involve the uveal tract and mucosal membranes, including the conjunctiva. In contrast to cutaneous melanoma, they often present at an advanced clinical stage, are associated with worse clinical outcomes and show poorer responses to immunotherapy. The mutational load within most non-cutaneous melanomas reflects their lower ultraviolet light (UV) exposure. The genetic drivers within non-cutaneous melanomas are heterogeneous. Within ocular melanomas, posterior uveal tract melanomas typically harbour one of two distinct, sets of driver mutations and alterations of clinical and biological significance. In contrast to posterior uveal tract melanomas, anterior uveal tract melanomas of the iris and conjunctival melanomas frequently carry both a higher mutational burden and specific mutations linked with UV exposure. The genetic drivers in iris melanomas more closely resemble those of the posterior uveal tract, whereas conjunctival melanomas harbour similar genetic driver mutations to cutaneous melanomas. Mucosal melanomas occur in sun-shielded sites including sinonasal and oral cavities, nasopharynx, oesophagus, genitalia, anus and rectum, and their mutational landscape is frequently associated with a dominant process of spontaneous deamination and infrequent presence of UV mutation signatures. Genetic drivers of mucosal melanomas are diverse and vary with anatomic location. Further understanding of the causes of already identified recurrent molecular events in non-cutaneous melanomas, identification of additional drivers in specific subtypes, integrative multi-omics analyses and analysis of the tumor immune microenvironment will expand knowledge in this field. Furthermore, such data will likely uncover new therapeutic strategies which will lead to improved clinical outcomes in non-cutaneous melanoma patients.

Iris Colour and the Risk of Developing Uveal Melanoma

Uveal melanoma (UM) is a global disease which especially occurs in elderly people. Its incidence varies widely between populations, with the highest incidence among Caucasians, and a South-to-North increase in Europe. As northern Europeans often have blond hair and light eyes, we wondered whether iris colour may be a predisposing factor for UM and if so, why. We compared the distribution of iris colour between Dutch UM patients and healthy Dutch controls, using data from the Rotterdam Study (RS), and reviewed the literature regarding iris colour. We describe molecular mechanisms that might explain the observed associations. When comparing a group of Dutch UM patients with controls, we observed that individuals from Caucasian ancestry with a green/hazel iris colour (Odds Ratio (OR) = 3.64, 95% Confidence Interval (CI) 2.57-5.14) and individuals with a blue/grey iris colour (OR = 1.38, 95% CI 1.04-1.82) had a significantly higher crude risk of UM than those with brown eyes. According to the literature, this may be due to a difference in the function of pheomelanin (associated with a light iris colour) and eumelanin (associated with a brown iris colour). The combination of light-induced stress and aging may affect pheomelanin-carrying melanocytes in a different way than eumelanin-carrying melanocytes, increasing the risk of developing a malignancy.

[New molecular pathological strategies for malignant iris tumors]

BACKGROUND

Molecular pathological research offers new chances for the diagnostic and therapeutic management of malignant iris tumors. Besides immunohistological and polymerase chain reaction analyses further techniques, such as multiplex ligation-dependent probe amplification, microsatellite analyses and next-generation sequencing are able to detect various mutations in the tumor genome.

OBJECTIVE

An up to date review of new molecular pathological strategies for malignant iris tumors was carried out.

METHODS

This article provides a review of the recent literature based on a PubMed search and clinical experience with iris tumors.

RESULTS

The diagnostic characteristics and targeted treatment options are presented, exemplified by iris melanoma and iris carcinoma metastases. In iris melanomas, mutations in the GNA11 and GNAQ genes (in approximately 85% of the cases) seem to be important. Furthermore, the monosomy-3 status should be investigated in these tumors. In iris lymphomas, molecular pathological analyses are essential for an exact diagnosis. Detection of mutations in MYD88, BRAF, KLF2, ID3, TCF3, STAT3, RHo, TET2, IDH2, CXCR4, CD79B and DNMT3A are helpful. In particular, the detection of the CD20 antigen is of therapeutic relevance because this lymphoma subgroup responds well to rituximab, a CD20 antibody treatment. In iris carcinoma metastases, investigations for mutations are helpful because then a targeted treatment seems to be possible.

CONCLUSION

Molecular pathological analyses will become essential in the future management of iris tumors because they play a key role towards a personalized treatment approach.