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H. Faraji, S. Brownstein, M.W. Dorey, D.R. Jordan, S. Robertson; Immunohistochemical Analyses of Uveal Melanoma and Comparison with Primary Acquired Melanosis of the Conjunctiva . Invest. Ophthalmol. Vis. Sci. 2004;45(13):1210.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To determine the immunohistochemical profile of uveal melanoma and to compare this to other melanocytic lesions including conjunctival nevi and primary acquired melanosis (PAM), normal uveal melanocytes, and nonmelanocytic intraocular tissues in order to demonstrate the most sensitive and specific immunomarker(s) to uveal melanoma. Methods: Retrospective and prospective case series. 19 specimens of uveal melanoma from 19 different patients were obtained from the ocular pathology registry of the University of Ottawa Eye Institute from May 2000 to March 2003. Sections from each formalin–fixed, paraffin–embedded specimen were stained with hematoxylin–eosin and periodic acid–Schiff and immunostained with anti–S–100, HMB–45 (anti–gp100), melanoma cocktail (anti–melan–A and HMB–45), pan melanoma cocktail (anti–melan–A, HMB–45, and anti–tyrosinase), MART–1 (anti–melan–A), MIB–1 (anti–Ki67), anti–tyrosinase (T311), anti–microphthalmia–associated transcription factor (D5), and vimentin. The specimens were processed with the 3,3 diaminobenzidine (DAB) substrate and the vector red (VR) substrate methods. We similarly looked at 23 melanocytic conjunctival lesions (11 PAM with atypia, 5 PAM without atypia and 7 compound nevi), and in the 19 globes at normal choroidal melanocytes as well as nonmelanocytic tissues (optic nerve, Schwann cells, and nonpigmented ciliary epithelium). Results: The uveal melanomas were best demonstrated with the HMB–45, anti–MIB–1, anti–microphthalmia–associated transcription factor, melanoma cocktail, pan melanoma cocktail, MART–1, vimentin, and anti–tyrosinase all of which showed 100% positive staining. The uveal melanomas were slightly (95%) less frequently stained by anti–S–100. HMB–45, which stained the uveal melanomas in 100% of the specimens, was most specific (90%) to the tumor cells, similar to our findings with PAM with atypia of the conjunctiva. All of the other antibodies stained normal uveal melanocytes and nevus cells and PAM of the conjunctiva as well as the malignant tumor cells. The VR substrate technique allowed for easy differentiation of the melanin pigment from the dark red pigmented immunostain in the tumor cells of the uveal melanomas. Conclusions: In this study we demonstrated that HMB–45 is the most specific antibody for uveal melanoma. The popular DAB substrate is often not useful in the identification of tumor cells especially in heavily pigmented uveal melanomas and should be replaced by the superior VR substrate.
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