Conjunctival melanoma and melanosis: a reappraisal of terminology, classification and staging

This paper aims to stimulate debate on the terminology, classification, grading and staging of conjunctival melanosis and melanoma. We audited our results with 76 invasive conjunctival melanomas. Staging according to the sixth edition of the Tumour Node Metastasis (TNM) system did not correlate well with tumour extent and outcome. Approximately 50% of invasive melanomas were associated with 'primary acquired melanosis with atypia', a term which in our opinion underestimates the gravity of this disease. We also found deficiencies in the grading, terminology and classification of conjunctival melanocytic abnormalities. In summary, we suggest that the term 'primary acquired melanosis' be reserved for clinical diagnosis. Histologically, this abnormality can be categorized more precisely as either 'hypermelanosis' or 'conjunctival melanocytic intraepithelial neoplasia (C-MIN)'. 'Primary acquired melanosis without atypia' can be termed more accurately as 'C-MIN without atypia'. In view of the high risk of invasive melanoma, we suggest that 'primary acquired melanosis with atypia' be termed 'C-MIN' with atypia, with the more severe changes regarded as melanoma in situ. To improve objectivity in the reporting of C-MIN, we propose a scoring system based on horizontal and vertical spread and degree of severity of melanocytic atypia. We suggest that the TNM staging system for conjunctival melanoma be revised to: (i) include a Tis stage; (ii) take account of tumour size, quadrant and caruncular involvement; and (iii) improve staging of any local invasion beyond conjunctiva.