Pathology of conjunctival melanocytic neoplasms

Abstract

Abstract Purpose To describe the classification, grading and staging of conjunctival melanocytic proliferation. Methods We have audited our experience with conjunctival melanomas, using a novel mapping system and have found shortcomings in the current Tumour Node Metastasis (TNM) staging system. We have also reviewed our cases of intra‐epithelial melanocytic neoplasia and confirmed other authors’ impressions that conjunctival ‘primary acquired melanosis with atypia’ is histologically similar to cutaneous in situ melanoma. To improve objectivity in the reporting of conjunctival intra‐epithelial melanocytic neoplasia, we propose a scoring system based on pattern of melanocytic infiltration, density of melanocytes & degree of cellular atypia. Results The term ‘conjunctival melanosis’ should be used only to describe the slit‐lamp appearance of hyperpigmentation. Histologically, this abnormality should be categorized as ‘hypermelanosis’ or ‘melanocytosis’. Hypermelanosis can either be primary or secondary to ocular or systemic disease. Benign melanocytosis comprises conjunctival melanocytic hyperplasia and naevi. Malignant melanocytosis is essentially melanoma, which is primary (in situ or invasive) or secondary (i.e., spreading to conjunctiva from adjacent tissues) or rarely metastatic. We suggest that the TNM staging system for conjunctival melanoma should be revised to: (1) include a Tis stage; (2) take account of superficial extent, invasion of adjacent tissues and caruncular involvement, in stages TI to TIII; and (3) to sub‐categorize TIV disease so that there is better correlation with likely mortality. Conclusion We have revised the classification of conjunctival melanocytic proliferations & improved the grading and staging of melanoma. These developments should be useful in treatment & research.