Validation of the Newly Proposed World Health Organization Classification System for Conjunctival Melanocytic Intraepithelial Lesions: A Comparison with the C-MIN and PAM Classification Schemes

A Multicenter Study Validates the WHO 2022 Classification for Conjunctival Melanocytic Intraepithelial Lesions With Clinical and Prognostic Relevance

Several nomenclature and grading systems have been proposed for conjunctival melanocytic intraepithelial lesions (C-MIL). The fourth "WHO Classification of Eye Tumors" (WHO-EYE04) proposed a C-MIL classification, capturing the progression of noninvasive neoplastic melanocytes from low- to high-grade lesions, onto melanoma in situ (MIS), and then to invasive melanoma. This proposal was revised to the WHO-EYE05 C-MIL system, which simplified the high-grade C-MIL, whereby MIS was subsumed into high-grade C-MIL. Our aim was to validate the WHO-EYE05 C-MIL system using digitized images of C-MIL, stained with hematoxylin and eosin and immunohistochemistry. However, C-MIL cases were retrieved from 3 supraregional ocular pathology centers. Adequate conjunctival biopsies were stained with hematoxylin and eosin, Melan-A, SOX10, and PReferentially expressed Antigen in Melanoma. Digitized slides were uploaded on the SmartZoom platform and independently scored by 4 ocular pathologists to obtain a consensus score, before circulating to 14 expert eye pathologists for independent scoring. In total, 105 cases from 97 patients were evaluated. The initial consensus diagnoses using the WHO-EYE04 C-MIL system were as follows: 28 benign conjunctival melanoses, 13 low-grade C-MIL, 37 high-grade C-MIL, and 27 conjunctival MIS. Using this system resulted in 93% of the pathologists showing only fair-to-moderate agreement (kappa statistic) with the consensus score. The WHO-EYE05 C-MIL system (with high-grade C-MIL and MIS combined) improved consistency between pathologists, with the greatest level of agreement being seen with benign melanosis (74.5%) and high-grade C-MIL (85.4%). Lowest agreements remained between pathologists for low-grade C-MIL (38.7%). Regarding WHO-EYE05 C-MIL scoring and clinical outcomes, local recurrences of noninvasive lesions developed in 8% and 34% of the low- and high-grade cases. Invasive melanoma only occurred in 47% of the cases that were assessed as high-grade C-MIL. This extensive international collaborative study is the first to undertake a comprehensive review of the WHO-EYE05 C-MIL scoring system, which showed good interobserver agreement and reproducibility.

Factors affecting recurrence and metastasis in conjunctival melanoma

PURPOSE

To evaluate clinical and demographic characteristics and factors affecting recurrence, metastasis, and survival in conjunctival melanoma (CM).

METHODS

The clinical records of 45 patients who were treated for CM between October 1998 and June 2022 were retrospectively evaluated. Age, gender, presence of underlying conjunctival nevus-primary acquired melanosis (PAM), tumor stage according to the 8th edition of the American Joint Committee on Cancer (AJCC) staging system, tumor basal diameter, tumor thickness, lymph node (LN) involvement, metastasis, presence of tumor at the surgical margin, treatment method, need for adjuvant therapy, local tumor control, recurrence, and survival were recorded.

RESULTS

Twenty-one (46.7%) patients were female and 24 (53.3%) patients were male. The mean age at diagnosis was 53.2 ± 16.1 years. Median follow up time was 12 (1-300) months. Fifteen (33.3%) patients had conjunctival PAM; 2 (4.4%) patients had conjunctival nevus. The tumor stage was T1 in 24 (55.8%), T2 in 13 (30.2%), and T3 in 6 (14.0%) of the cases. The T stage in 2 cases could not be determined. For stage T1 and T2 CM, in addition to excisional biopsy (EB) and cryotherapy, alcohol epitheliectomy (AE) was performed in 17 cases (37.8%), superficial sclerectomy (SS) was performed in 7 (15.6%), and amnion membrane transplantation (AMT) due to a large conjunctival defect in 9 (20.0%). Six (14.0%) T3 cases underwent primary exenteration. Positive surgical margins were observed in 23 (51.1%) of the excised tumors at histopathologic examination. Adjuvant topical mitomycin-C (MMC) was used in 7 (30.4%) and strontium-90 episcleral brachytherapy in 4 (17.4%) of the 23 cases with tumor-positive borders. During the follow-up, recurrence was seen in 14 (31.1%) cases. According to Kaplan Meier analysis, the mean time to recurrence development was 90.5 ± 16.1 months and the 5-year recurrence free rate was 52.0%. Fourteen of the recurrent cases underwent EB + cryotherapy, 3 underwent AE + SS, and 3 underwent secondary exenteration. Metastasis and LN involvement occurred in 11 (24.4%) and 8 (17.8%) of the cases, respectively. Four (8.9%) cases expired during follow-up. According to Kaplan-Meier analysis, the mean time to metastasis was 106.2 ± 17.3 months and the 5-year metastasis free rate was 52.0%. While recurrence was more frequent in CM developing from PAM/nevus, metastasis was more frequent in men and those with LN involvement.

CONCLUSION

Conjunctival melanoma was a malignant tumor with high recurrence and metastasis rates. Precursor nevus/PAM is a risk factor for recurrence, while male gender and regional LN involvement were risk factors for metastasis in this study.

Dendritic Melanocytic Hyperplasia in Pterygia: A Potential Source of Diagnostic Confusion with Primary Acquired Melanosis

Introduction

The aim of this study was to report the nearly ubiquitous prevalence of melanocytic hyperplasia in benign pterygia/pingueculae and establish that the entity is insufficiently recognized.

Methods

This is a retrospective immunohistochemical pathology case series of 30 consecutive pterygia/pingueculae samples selected from an ophthalmic pathology database at a single institution. Histopathologic and immunohistochemistry analyses with anti-SOX-10 and anti-MART-1 antibodies were used for identifying melanocytes. The number of squamous cells intervening between melanocytes was determined.

Results

The frequency of dendritic melanocytes was found to meet the criteria for dendritic melanocytic hyperplasia in 29 of 30 pterygia/pingueculae samples using specific antibodies. Melanocytes were found in several patterns: diffuse (28%), multifocal (28%), and focal (44%). In each case, the melanocytes were distributed as single melanocytes at the base; clusters of melanocytes were seen in 17% of samples. There were an average of about two intervening epithelial cells between melanocytes at the base.

Conclusion

When diagnosed with immunohistochemistry, dendritic melanocytic hyperplasia is nearly ubiquitous in pterygia and pingueculae. Melanocytic hyperplasia may have a distribution that includes nests and single melanocytes above the basal layer, which can be confused with forms of primary acquired melanosis. It is important for pathologists to recognize these lesions as a distinct benign clinicopathologic entity.

Conjunctival amelanotic melanoma presenting as a multifocal pink lesion

Conjunctival amelanotic malignant melanoma is a rare form of melanoma, which lacks visible pigment and is commonly located underneath the eyelids in the bulbar conjunctiva. In this report, we described a case of a Caucasian women in her 70s who presented with unilateral irritation and tenderness following cataract surgery. On eversion of the eyelid, two elevated pink lesions were noted. Tumour - Node - Metastasis staging with the American Joint Committee on Cancer staging system eighth edition was T3C and required multiple excisions and reconstruction procedures. This case exemplified the diagnostic pitfall of conjunctival amelanotic malignant melanoma, which is a potentially life-threatening disease and the importance of histopathology in the diagnostic process.

Bone metastasis in a case of primary acquired melanosis with atypia resulting from conjunctiva melanoma

A 66-year-old woman presented to a tertiary referral centre with a diagnosis of limbal stem cell deficiency secondary to multiple treatments for primary acquired melanosis (PAM) by her referring ophthalmologists. She was known with primary acquired melanosis with severe atypia of the right eye which had been treated with several excisions, cryotherapy and topical chemotherapy. She had PAM over 360° of alternating intensity. Throughout the follow-up period, she developed a cataract and subsequent a retinal detachment for which she underwent a phacovitrectomy on the right eye. There was no nodule present nor did the routine lymph nodes inspection show any enlargement. No abnormalities were observed on intranasal examination. Seven years after the last excision, a metastasis to the spine (Th3) was diagnosed. A complete systemic work-up and a pathological examination did not show any alternative primary melanoma in the body. The original histological material was reviewed again by an ophthalmopathologist. After a new round of stains and immunohistochemistry, the presence of atypical melanocytes in both the epithelium and stroma were found in a scar region leading to a renewed conclusion that the PAM in question was actually the primary melanoma.

Real-life data of adjuvant IFN-α2b and MMC in conjunctival melanocytic lesions

PURPOSE

We herein compare topical interferon alpha 2b (IFN-α2b) to topical mitomycin C (MMC) in the adjuvant management after excision of primary acquired melanosis with atypia (PAM) and melanoma of the conjunctiva/cornea (CM).

METHODS

We included 25 tumors from 25 patients (six with PAM and 19 with CM). After surgical excision, four patients started with adjuvant IFN-α2b (two in combination with radiotherapy), 19 with MMC, and two with radiotherapy alone. Five patients were switched from initial MMC/radiotherapy to IFN-α2b during follow-up. Efficacy was assessed via time to tumor recurrence and initial therapy response.

RESULTS

With initial IFN-α2b, three patients (3/4, two with additional radiotherapy) showed complete remission (follow-up: 1478-1750 days) and one recurrence (1/4) was noted after 492 days. With initial MMC, no recurrence was recorded in 15 of the 19 patients (follow-up: 99-4732 days). Five patients were switched from MMC or radiotherapy to IFN-α2b: two patients showed complete remission (2/5), while another two (2/5) experienced recurrences and remained without recurrence after repeated courses of IFN-α2b (follow-up: 1798 and 1973 days). Only one patient showed incomplete response. Adverse effects were recorded in five patients, all received MMC.

CONCLUSION

Topical IFN-α2b (arguably together with radiotherapy) may be a viable alternative to MMC in PAM and CM. We observed fewer side effects at similar response rates. However, when response to MMC was poor, IFN-α2b may also be of limited utility.

Bindehautdegenerationen und -neoplasien

Erhabenheiten der Bindehaut entstehen durch Gewebevermehrung, die entweder degenerativ oder neoplastisch, aber auch entzündlich sein können. In diesem Artikel werden degenerative (Pterygium und Pinguecula) sowie benigne und maligne neoplastische Bindehautveränderungen (epitheliale, melanozytäre und vaskuläre Tumoren, Choristome sowie Metastasen) bezüglich der Pathogenese, Symptome, Diagnostik und aktuellem Stand der Behandlung dargestellt.

[Conjunctival Degeneration and Neoplasia]

Conjunctival tumors result from gain of tissue, which can be either degenerative or neoplastic, but also inflammatory. In this article, degenerative (pterygium and pinguecula) as well as benign and malignant neoplastic conjunctival changes (epithelial, melanocytic and vascular tumors, choristomas as well as metastases) are discussed with regard to pathogenesis, symptoms, diagnostics and current status of treatment.

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.

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.