Malign Melanomlar ile Melanositik Nevüs Ayrımında EGFR, CCND1 ve RREB1 Genlerini Hedef Alan FISH Testinin Yeri

Abstract

Melanocytic nevus (MN) may on occasion be difficult to distinguish from malignant melanoma (MM) histopathologically. Fluorescent in situ hybridization (FISH) has been demonstrated to be of use for the diagnosis of melanocytic neoplasms of the skin. In this study, the effectiveness of the standart melanoma FISH test (4-way probe targeting RREB1, CCND1, MYB genes and centromere 6) and additionally probes, targetting EGFR, TP53, MDM2 and TP53 genes, in differentiating melanomas from melanocytic nevi were investigated. Standard FISH test was performed on 24 MM and 24 MN samples, but EGFR, TP53, MDM2 and TP53 gene copy numbers were investigated in 16 of 24 MM and 24 MN using FISH method. The incidence of FISH-detected positive genomic copy aberrations (4-way probe, and others) was determined as 83,3% in 24 MM cases, and 5,2% in 24 MN. Statistically significant differences were found between the MM and MN groups in terms of CCND1, RREB1, EGFR amplifications (p<0.001, p<0.05, p˂0.05), but there was no association between histopathological features and detected abnormalities (p>0,05). In additionally, all 5 acral lentiginous melanomas, could be analysed, had EGFR amplifications. In conclusion, CCND1, RREB1, and EGFR amplifications have diagnostic significance for MM. The FISH test is very effective in terms of its use as an adjunct to histopathological methods. But centromere controlled probes should be used to avoid false positive results.