Fish analysis of chromosome 3 and 6 on fine needle aspiration biopsy identifies distinct uveal melanoma subgroups

Abstract

Abstract Purpose: Some evidence suggests that uveal melanomas develop following one of two ways in a pathogenetic model, one starting with a loss of chromosome 3 and the other with extra copies of 6p (+6p), heaving different prognostic outcome. The aim of this study was to analyze the role of Fluorescence In Situ Hybridization (FISH) applied on Fine Needle Aspiration Biopsy (FNAB) specimen to in‐vivo verify the presence/ absence of this bifurcated pathogenetic and prognostic model. Methods: Thirty‐five consecutive patients, affected by posterior uveal melanoma (>3,5 mm in thickness), scheduled for Iodine‐125 brachitherapy, underwent intraoperative trans‐scleral FNAB just before plaque implantation. Specimens underwent Fluorescent in Situ Hybridisation (FISH) to detect chromosome 3 and 6 (as +6p and 6q‐) status. Results: Minimum follow‐up was 12 months (range: 12‐40 months). All cases gave enough material for cytogenetic analysis. +6p and monosomy 3 were mutually exclusive in 29 cases (83%). Three cases (8.5 %) showed no chromosome 3 and 6 abnormalities and three cases (8.5%) showed both monosomy 3 and +6p. Monosomy 3 was not significantly related (p>.05) to tumour dimensions and tumour location (choroid/ciliary body). No major complications or extrascleral extension were documented. Three patients (8,5%) with monosomy 3 developed metastatic disease during the follow up. Conclusions: In‐vivo detection of cytogenetic prognostic‐related characteristics in posterior uveal melanoma is possible analyzing cytologic specimens obtained by transcleral FNAB before episcleral plaque implantation. FISH analysis for chromosome 3 and 6 status could offer more prognostic information than monosomy 3 alone.