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Sarah Alghamdi, Ana Beatriz Toledo Dias, Mohammed F Qutub, Julia Caminal, Josep M. Marti, Miguel N Burnier; The Importance of Sox-10 Expression in Uveal Melanoma. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5318.
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© ARVO (1962-2015); The Authors (2016-present)
An immunohistochemical panel of S100 protein, Melan A and HMB-45 is commonly used to confirm the diagnosis of malignant melanoma due to the lack of adequate specificity and sensitivity of a single marker. Sox10 is a neural crest transcription factor crucial for specification of Schwann cells and melanocytes. Sox-10 has been shown to be a sensitive marker of cutaneous melanoma, including spindle and desmoplastic subtypes, which are known to be negative for melanocytic markers such as Melan A and HMB-45. This study aimed to evaluate Sox-10 expression in uveal melanoma.
Thirty-nine uveal melanoma cases over a period of 35 years (1980-2014) were retrieved from the Henry C. Witelson Ocular Pathology Laboratory. Formalin-fixed, paraffin-embedded blocks of enucleated eyes with uveal melanoma were cut and stained using an anti-Sox-10 mouse monoclonal antibody. The staining was scored based on the extent of the nuclear expression: diffuse when staining was seen in more than 50% of cells, and focal when it was seen in less than 50% of cells.
Of the 39 uveal melanomas studied, 12 were epithelioid (31%), 13 were spindle (33%), and 14 were mixed (36%) subtypes. The mean age of diagnosis was 69 with no gender predilection. Thirty-five showed diffuse nuclear positivity for Sox-10 (90%), two showed focal nuclear staining (5%), while two were negative (5%). Positivity for Sox-10 was also noted in the inner and outer nuclear layers of the retina in 78% of enucleated eyes. Overall, 17% of cases showed Sox-10 nuclear staining in retina pigmented epithelium. The uninvolved ciliary body, choroid, and iris showed focal positivity in 48%, 44%, and 11%, respectively. Five cases expressed Sox-10 in Schwann cells of the scleral nerves (13%).
To the best of our knowledge, Sox-10 expression in uveal melanoma has never been investigated. Sox-10 expression was a sensitive, easily recognizable marker for uveal melanoma; however, it was also positive in normal ocular structures. This study suggests that Sox-10 can be incorporated in the panel for diagnosing uveal melanoma tumors. Furthermore, the observation of distinct, diffuse nuclear Sox-10 expression in retinal inner and outer nuclear layers, is a finding that warrants further investigation.
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