Diagnostic Fine-Needle Aspiration Biopsy for Iris Melanoma

Iris Melanoma: Management and Prognosis

Iris melanomas represent 2–5% of uveal melanomas. Iris melanomas vary in their size, shape, degree of pigmentation and clinical behavior. The main local clinical complications of iris melanomas are tumor vascularization, ectropion uvea, pupillary distortion, pigment dispersion, sector cataract, chronic uveitis, hyphema and glaucoma with irreversible optic nerve damage. The most effective treatment for iris nevus and melanoma remains debatable; treatment modalities have been proposed depending on the local status as well as the age and general condition of the patient. A melanocytic iris nevus is usually observed until documented progression is identified. In this case, radiotherapy or surgical resection is generally performed. Cataract, glaucoma and limbal stem cell deficiency are usually secondary to radiotherapy, while incomplete tumor excisions, which could lead to recurrence, hemorrhage, vitreous loss, dislocated lens, iridocyclitis, macular edema, retinal detachment, glaucoma and cataract, are related to surgical resection. In some cases, a combination of radiotherapy and surgery is used. Conservative treatment is an efficient alternative to enucleation and allows good local tumor control.

Uveal melanoma

Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. UMs are usually initiated by a mutation in GNAQ or GNA11, unlike cutaneous melanomas, which usually harbour a BRAF or NRAS mutation. The annual incidence in Europe and the USA is ~6 per million population per year. Risk factors include fair skin, light-coloured eyes, congenital ocular melanocytosis, ocular melanocytoma and the BAP1-tumour predisposition syndrome. Ocular treatment aims at preserving the eye and useful vision and, if possible, preventing metastases. Enucleation has largely been superseded by various forms of radiotherapy, phototherapy and local tumour resection, often administered in combination. Ocular outcomes are best with small tumours not extending close to the optic disc and/or fovea. Almost 50% of patients develop metastatic disease, which usually involves the liver, and is usually fatal within 1 year. Although UM metastases are less responsive than cutaneous melanoma to chemotherapy or immune checkpoint inhibitors, encouraging results have been reported with partial hepatectomy for solitary metastases, with percutaneous hepatic perfusion with melphalan or with tebentafusp. Better insight into tumour immunology and metabolism may lead to new treatments.

[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.