Background

In the differential diagnosis of conjunctival melanocytic lesions, HMB45, S100 and Melan-A (MART-1) became the most important immunohistological antigens that help to distinguish melanomas from benign melanocytic lesions of the conjunctiva.1 S100, an acidic protein, and Melan-A, a melanosomal antigen, both mark the extension of a melanocytic lesion.2 3 Jakobiec et al showed that S100 A1 improves the diagnostic assessment of conjunctival nevi and melanomas.2 HMB45, a cytoplasmic oncofetoprotein, is a marker for a low grade of differentiation.4 Its expression is increased in conjunctival melanoma and primary acquired melanosis (PAM) with atypia.1 HMB 45, Melan-A, S100 and Ki67 as a proliferation index became part of the …