Background  

Monosomy 3 is a highly specific marker for poor prognosis in posterior uveal melanoma. Unfortunately, cytogenetic prognostication is limited to enucleated eyes or resected tumors. The aim of this study was to evaluate mid-term natural history and safety of in vivo detection of chromosome 3 status in posterior uveal melanomas undergoing plaque brachytherapy.

Methods  

A 25-gauge transscleral fine needle aspiration biopsy (FNAB) was performed in 32 eyes affected by posterior uveal melanoma undergoing plaque brachytherapy, just before applying the radioactive plaque. Sampled material underwent fluorescence in situ hybridization (FISH) with centromeric probes for chromosome 3. All patients had a follow-up of at least 36 months.

Results  

Mean follow-up was 47.1 ± 8.5 months. Mean largest basal diameter and mean thickness of the tumors were 12.5 ± 2.7 mm and 8 ± 2.3 mm respectively. FNAB yielded sufficient material in 26 of 32 cases (81.2%). Adequacy of the sample ranged from 91.1% (ciliary body tumors) to 76.8% (choroidal tumors). Seventeen cases had monosomy 3 (65.3%). No correlation was found between monosomy 3 and tumor dimensions or location (ciliary body vs choroidal tumors). No early and mid-term local complications were documented. Seven patients (21.8%) died during follow-up: five (15.6%) of them died due to metastatic disease (all had monosomy 3 tumors).

Conclusions  

Posterior uveal melanomas may be adequately and safely sampled, by intra-operative transscleral FNAB, to detect in vivo monosomy 3.