Sentinel lymph node biopsy in the management of conjunctival melanoma: current insights

Conjunctival Melanocytic Lesions

CONTEXT.—

Conjunctival melanocytic lesions consist of a variety of neoplastic and nonneoplastic conditions. These include benign processes such as primary intraepithelial hypermelanosis and melanocytic hyperplasia, secondary forms of intraepithelial hypermelanosis and melanocytic hyperplasia, melanocytic nevi, melanocytic proliferations with malignant potential, and melanoma.

OBJECTIVE.—

To provide a concise yet comprehensive resource regarding the histopathologic diagnosis of conjunctival melanocytic lesions. We aim to detail and clarify the numerous classification schemes that exist for junctional melanocytic proliferations of the conjunctiva (known as primary acquired melanosis or PAM; also termed conjunctival melanocytic intraepithelial neoplasia or C-MIN). Although not uniformly adopted, C-MIN is classified by using a numeric system based on a defined set of criteria. A less complex scheme (conjunctival melanocytic intraepithelial lesion or CMIL) has recently been proposed by the World Health Organization. Additionally, we aim to update the reader regarding molecular features and prognostic indicators.

DATA SOURCES.—

Peer-reviewed literature and archived cases for illustration.

CONCLUSIONS.—

Accurate histologic classification is essential, as PAM/C-MIN/CMILs that have a significant potential to progress to invasive melanoma may be clinically indistinguishable from low-risk lesions. Conjunctival melanoma (CM) more closely resembles cutaneous melanoma in terms of its pathogenesis and molecular features, compared to melanoma arising at other mucosal sites or to uveal melanoma. Depth of invasion and ulceration status, among other factors, have emerged as important prognostic indicators in CM. Sentinel lymph node biopsy may provide further prognostic information. Lastly, integration of pathologic and clinical findings is essential at this anatomically sensitive location to determine appropriate clinical management.

Structural Protein Analysis of Driver Gene Mutations in Conjunctival Melanoma

In recent years, there has been tremendous enthusiasm with respect to detailing the genetic basis of many neoplasms, including conjunctival melanoma (CM). We aim to analyze five proteins associated with CM, namely BRAF, NRAS, c-KIT, NF1, and PTEN. We evaluated each protein for its intrinsically disordered protein regions (IDPRs) and its protein-protein interactions (PPI) with the Predictor of Natural Disordered Protein Regions (PONDR^®) and the Search Tool for the Retrieval of Interacting Genes (STRING^®). Our PONDR^® analysis found high levels of IDPRs in all five proteins with mutations linked to CM. The highest levels of IDPRs were in BRAF (45.95%), followed by PTEN (31.76%), NF1 (22.19%), c-KIT (21.82%), and NRAS (14.81%). Our STRING analysis found that each of these five proteins had more predicted interactions then expected (p-value < 1.0 × 10⁻¹⁶). Our analysis demonstrates that the mutations linked to CM likely affected IDPRs and possibly altered their highly complex PPIs. Quantifying IDPRs in BRAF, NRAS, c-KIT, NF1, and PTEN and understanding these protein regions are important processes as IDPRs can be possible drug targets for novel targeted therapies for treating CM.

Sentinel Node Biopsy for Conjunctival Melanoma; Single Centre Experience and Review of Current Literature

Purpose

To evaluate the role of sentinel lymph node (SLN) biopsy in patients with conjuctival melanoma (CjM).

Study design

Retrospective observational cohort study and literature review.

Subjects

Slovenian patients with CjM are included in the study.

Methods

Prospectively collected data of CjM patients treated from June 2005 to December 2016 were retrospectively analyzed.

Main outcome measures

The numbers of SLN biopsy procedures, positive and false positive SLN, and local and regional relapses have been described together with overall survival.

Results

From June 2005 until December 2016, 24 patients with CjM were treated. The median follow-up time was 65.3 months. The mean Breslow thickness was 1.5 mm (sd = 1.8 mm), and ulceration was present in 29% of cases. Altogether, 14/24 (58%) SLN biopsy procedures were performed. SLN was positive in 2/14 (14%) cases. The estimated 5-year overall survival (OS) of the group was 72.5%, with a median survival of 151 months (95% CI 77–224). From January 2013 to January 2020, five (5/140, 3%) authors reported results comparable to our study.

Conclusion

Our results confirm that CjM is a rare disease with approximately 14% of positive SLN. At the moment, there are no firm conclusions regarding who would benefit most from SLN biopsy or whether or not CLND should be offered. Data from literature emphasize the need for consistent and uniform staging and future multicentric studies.

Conjunctival melanoma: New insights in tumour genetics and immunology, leading to new therapeutic options

Recent developments in oncology have led to a better molecular and cellular understanding of cancer, and the introduction of novel therapies. Conjunctival melanoma (CoM) is a rare but potentially devastating disease. A better understanding of CoM, leading to the development of novel therapies, is urgently needed. CoM is characterized by mutations that have also been identified in cutaneous melanoma, e.g. in BRAF, NRAS and TERT. These mutations are distinct from the mutations found in uveal melanoma (UM), affecting genes such as GNAQ, GNA11, and BAP1. Targeted therapies that are successful in cutaneous melanoma may therefore be useful in CoM. A recent breakthrough in the treatment of patients with metastatic cutaneous melanoma was the development of immunotherapy. While immunotherapy is currently sparsely effective in intraocular tumours such as UM, the similarities between CoM and cutaneous melanoma (including in their immunological tumour micro environment) provide hope for the application of immunotherapy in CoM, and preliminary clinical data are indeed emerging to support this use. This review aims to provide a comprehensive overview of the current knowledge regarding CoM, with a focus on the genetic and immunologic understanding. We elaborate on the distinct position of CoM in contrast to other types of melanoma, and explain how new insights in the pathophysiology of this disease guide the development of new, personalized, treatments.

Orbital exenteration for conjunctival melanoma: comparison of long-term outcome between individualised and conventional techniques

BACKGROUND

Growing evidence supports an individualised approach rather than radical surgery for conjunctival melanoma (CM). This study aimed to compare the long-term outcome between individualised and conventional exenteration techniques.

METHODS

Our study retrospectively recruited advanced CM (clinical T3 stage) patients treated with individualised (13 cases) or conventional (18 cases) exenteration from June 2014 to April 2019. The individualised approach preserved at least three quadrants of the orbit, and the conventional procedures removed at least one third of the orbital tissues. The medical records were collected and analyzed during April 2020, including demographics, tumour characteristics, surgical details, postoperative rehabilitation and tumour-related prognosis.

RESULTS

The tumour basal diameter was statistically (P = 0.011) larger in the conventional group (23.3 ± 7.6 mm) than in the individualised group (15.4 ± 6.3 mm). More tissues were preserved in the individualised group, resulting in a shorter duration of wound healing (2.1 ± 0.6 vs. 3.6 ± 2.0 weeks, P = 0.018) and less incidence of hollow appearance (15% vs. 72%, P = 0.003) than the conventional group. After follow-up for 39.3 ± 17.3 months, a comparison of survival curves showed no significant differences (P = 0.638) between the two groups. The 1- and 2-year overall survival rates were estimated as 100% and 80.0% in the individualised group, and 93.8% and 72.5% in the conventional group, respectively. Low or mixed pigmentation was identified as the risk factor for tumour-related mortality based on multivariate regression analysis.

CONCLUSIONS

The individualised approach to exenteration offers improved aesthetic results while still maximises the curable chance for advanced CM.

Clinical treatment options for early-stage and advanced conjunctival melanoma

Conjunctival melanoma (CM) is an ocular malignant tumor arising from the bulbar and palpebral conjunctiva and from the caruncle. The treatment of early-stage CM is wide local excision, followed by cryotherapy to the margins and adjuvant therapy postoperatively. Advanced CM has a poor prognosis, and there is no consensus on its management. With the development of precision medicine, the identification of genetic alterations assumes great importance. The genetic characteristics of CM, such as BRAF, NRAS, and NF1 mutations, may provide potential therapeutic targets. For locally advanced tumors and metastatic disease, targeted therapy such as BRAF inhibitors and MEK inhibitors in vitro show therapeutic benefit. Some individual case reports indicate their potential effectiveness in advanced CM. In addition, immune checkpoint inhibitors, such as programmed cell death-1 and cytotoxic T lymphocyte antigen-4 inhibitors, have been successfully used for advanced cutaneous melanoma and may be effective in CM. Limited clinical case reports found immune checkpoint inhibitors effective in advanced CM. More clinical studies are needed.