title: Differential immunoreactivity of melanocytic lesions of the conjunctiva.
abstract: OBJECTIVE
  To evaluate the expression of S100NKI/C3 and HMB45 antigens in melanocytic lesions of the conjunctiva and the ability of HMB45 to aid assessment of neoplasia.
  
  
  RESULTS
  Stored formalin-fixed specimens of conjunctival melanomas and primary acquired melanosis were considered as participants and conjunctival naevi and racial melanosis as controls. Ninety-seven conjunctival melanocytic lesions were analysed using formalin-fixed paraffin-embedded material. These included 20 melanomas arising in the context of primary acquired melanosis (PAM), 22 melanomas arising without evidence of pre-existing PAM, seven cases of PAM with atypia, nine cases of PAM with no atypia, 35 conjunctival naevi and four cases of racial melanosis. S100 and NKI/C3 were similarly expressed in all lesions, with at least one of these markers positive in 100% of the lesions examined. HMB45 was expressed in 72.7% of primary melanomas and 85% of melanomas in the context of PAM; 42.8% of PAM with atypia expressed HMB45 while it was expressed in 11.1% of PAM without atypia and 8.5% of naevi. Racial melanosis cases did not express HMB45. S100 and NKI/C3 were expressed to a similar extent in all groups.
  
  
  CONCLUSIONS
  S100 and NKI/C3 are useful markers to assess the extent of melanocytic lesions in the conjunctiva. HMB45 immunoreactivity can act as a useful aid to histopathology for the distinction of benign from malignant conjunctival lesions, particularly in the context of primary acquired melanosis.
authors.affiliation: Pathology Department, Institute of Ophthalmology, University College London, UK.
authors.forename: N A
authors.initials: NA
authors.lastname: Sharara
authors.forename: R A
authors.initials: RA
authors.lastname: Alexander
authors.forename: P J
authors.initials: PJ
authors.lastname: Luthert
authors.forename: J L
authors.initials: JL
authors.lastname: Hungerford
authors.forename: I A
authors.initials: IA
authors.lastname: Cree
mesh_terms: D000951:Antigens, Neoplasm; D003229:Conjunctival Diseases / Q000378:metabolism / Q000473:pathology*; D003230:Conjunctival Neoplasms / Q000378:metabolism / Q000473:pathology*; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D008545:Melanoma / Q000378:metabolism / Q000473:pathology*; D058950:Melanoma-Specific Antigens; D008548:Melanosis / Q000378:metabolism / Q000473:pathology*; D009363:Neoplasm Proteins / Q000032:analysis; D009508:Nevus, Pigmented / Q000378:metabolism / Q000473:pathology*; D009418:S100 Proteins / Q000032:analysis
chemical_list: D000951:Antigens, Neoplasm; D058950:Melanoma-Specific Antigens; D009363:Neoplasm Proteins; D009418:S100 Proteins