Management of Conjunctival Melanoma: Critical Assessment of Sentinel Lymph Node Biopsy

Melanoma and Nanotechnology-Based Treatment

Melanoma is a malignant tumor arising in melanocytes from the basal layer of the epidermis and is the fifth most commonly diagnosed cancer in the United States. Melanoma is aggressive and easily metastasizes, and the survival rate is low. Nanotechnology-based diagnosis and treatment of melanoma have attracted increasing attention. Importantly, nano drug delivery systems have the advantages of increasing drug solubility, enhancing drug stability, prolonging half-life, optimizing bioavailability, targeting tumors, and minimizing side effects; thus, these systems can facilitate tumor cytotoxicity to achieve effective treatment of melanoma. In this review, we discuss current nanosystems used in the diagnosis and treatment of melanoma, including lipid systems, inorganic nanoparticles, polymeric systems, and natural nanosystems. The excellent characteristics of novel and effective drug delivery systems provide a basis for the broad applications of these systems in the diagnosis and treatment of melanoma, particularly metastatic melanoma.

Current Management of Conjunctival Melanoma Part 1: Clinical Features, Diagnosis and Histopathology

Conjunctival melanoma is a rare disease which makes up approximately 5% of ocular melanomas. The lesion may occur de novo or originate from a pre-existing nevus or primary acquired melanosis. Biomicroscopy is of paramount importance in diagnosis and follow-up of the disease, while other diagnostic modalities serve as supplementary tools. Many clinical and histopathological risk factors have been reported for prognosis. This review aims to address the clinical findings, differential diagnosis, diagnostic tools, prognostic factors, and staging of this disease.

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.

Sentinel Lymph Node Biopsy for Eyelid and Conjunctival Malignancy: A Report by the American Academy of Ophthalmology

PURPOSE

To determine the efficacy and safety of sentinel lymph node biopsy (SLNB) in the management of eyelid and conjunctival malignancy.

METHODS

A literature search was performed in August 2019 and January 2020 for articles published in English in the PubMed and Cochrane Library databases. This search yielded 151 articles that were reviewed for relevancy, of which 27 were deemed to have met the inclusion criteria for this assessment. The data from these articles were abstracted and the articles were rated for strength of evidence by the panel methodologist.

RESULTS

All 27 studies were rated level III, and a total of 197 SLNBs were reported. Diagnoses included conjunctival and eyelid cutaneous melanoma (85 and 42 patients, respectively), sebaceous gland carcinoma (35 patients), squamous cell carcinoma (26 patients), Merkel cell carcinoma (6 patients), pigmented epithelioid melanocytoid tumor (1 patient), mucoepidermoid carcinoma (1 patient), and signet ring carcinoma (1 patient). Tracer was found in regional lymph nodes in 100% of patients in 21 of 27 articles and in 191 of 197 patients overall. The number of lymph nodes removed ranged from 1 to 16, with most ranging from 1 to 5. Tumor-positive lymph nodes were found in 33 of 197 patients (16.8%), prompting recommendations for adjuvant treatments. Survival data were reported for 16 of these patients, with follow-up periods ranging from 3 to 36 months (average, 12.7 months). Fourteen of 16 patients received adjuvant treatments. Nine were alive and well, 1 was alive with metastases, and 6 had died of metastatic disease (including 2 patients who declined additional treatment). False-negative SLNB results were reported in 5 articles involving 9 of 197 procedures (4.6%). Complications were documented in 7 of 27 articles and included transient facial nerve weakness, persistent blue dye staining of the conjunctiva, neck hematoma, and suture abscess.

CONCLUSIONS

Sentinel lymph node biopsy is a promising procedure in patients with eyelid and conjunctival malignancy, and it is useful in identifying sentinel lymph nodes. However, at present, insufficient evidence exists showing that SLNB improves patient outcomes and survival. Recognition of microscopic metastatic disease may prove beneficial in staging and guiding adjuvant therapy.

Conjunctival Melanoma Angiotropic Microsatellitosis: A Mechanism of Local Extravascular Migratory Metastasis

Purpose

To report a case of local metastasis of conjunctival melanoma, which may occur via extravascular migratory metastasis (EVMM), and discuss its clinical relevance in conjunctival melanoma tumor staging and possible management implications.

Methods

Retrospective chart review of a single clinical case with clinicopathologic correlation.

Results

A 65-year-old male referred due to local recurrence of conjunctival melanoma at the caruncle was successfully treated after two excisional procedures with negative sentinel lymph node biopsies. Forty-eight months after initial presentation, the patient developed a nodular lesion representing local recurrence in the ipsilateral upper tarsal conjunctiva, distant from the primary tumor site. Histopathology showed nodules in the substantia propria in the absence of primary acquired melanosis. The tumor cells were found along the extravascular surface without intralymphatic or intravascular tumor cells consistent with local metastasis. One possible mechanism is angiotropic microsatellitosis leading to local EVMM. Additional neck CT imaging showed no lymphadenopathy.

Conclusion

EVMM via angiotropic microsatellitosis is another possible mechanism of noncontiguous local recurrence of conjunctival melanoma. Angiotropic microsatellitosis may represent a high-risk finding possibly related to increased melanoma-related mortality.

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

Purpose: To evaluate the role of sentinel lymph node biopsy (SLNB) in conjunctival melanoma (CM).

Methods: This article provides a review of the literature from PUBMED.

Results: Data on SLNB in the management of CM are scarce and only two relatively large cohorts have been reported. Although indication criteria for SLNB vary slightly, positive findings can be expected in 11%–13% of CM cases, including small tumors. False negative SLNB findings are rare (<10%). Failure to identify SLNB has been attributed to the surgical learning curve and recurrent tumors with scar tissue impeding spread of the tracer material. Reported 5-year survival rate following CM management including SLNB, is up to 79%, but there are no comparative cohort studies proving the assumed benefit. Adverse events reported were non-severe and transient.

Conclusion: Patients can potentially benefit from SLNB and the procedure can be offered to eligible patients. However, there is not enough evidence to support SLNB as a mandatory part of CM management.