KIT Mutations in Ocular Melanoma.
Michelle L Wallander, Lyska Emerson, Lester J Layfield. ARUP Institute for Clinical and Experimental Pathology, Salt Lake City, UT; University of Utah School of Medicine and ARUP Laboratories, Salt Lake City
Background: KIT and BRAF mutations are known to occur in cutaneous and mucosal melanomas. The anatomic location of the melanoma appears to correlate with the mutation present. BRAF mutations are most closely associated with melanomas arising in non-sun damaged skin while those arising at acral sites and on sun damaged skin are more often associated with KIT mutations. Melanomas with mutations in the KIT or BRAF genes may benefit from treatment with specific inhibitors. Little is known about the mutational characteristics of ocular melanomas.
Design: Forty-nine ocular melanomas (38 choroidal, 4 iris, 4 ciliary body and 3 conjunctival) were selected from the files of the Department of Ophthalmology and Pathology. High resolution melting curve analysis was performed to detect mutations in exons 9, 11, 13, and 17 of KIT and exons 12 and 18 of the PDGFRA gene. Results of the mutational analysis were correlated with the anatomical site of the ocular melanoma.
Results: Eight ocular melanomas contained mutations in either the KIT or the PFGFRA gene. Six of 38 (16%) choroidal melanomas were associated with mutations (KIT exon 11 = 1; KIT exon 13 = 1; KIT exon 17 = 2; PDGFRA exon 18 = 2). Two of 4 (50%) iris melanomas had KIT mutations both occurring in exon 11. Histologic type of melanoma did not correlate with the presence or site of the mutation.
|Tumor Site||Percentage with Mutations||Exons Involved (Number of Cases)|
|Choroidal||16%||KIT exon 11 (1) KIT exon 13 (1) KIT exon 17 (2) PDGFRA exon 18 (2)|
|Iris||50%||KIT exon 11 (2)|