Evaluation of chromogenic in situ hybridization for the determination of monosomy 3 in uveal melanoma.
BACKGROUND
Loss of 1 copy of chromosome 3 is considered a significant indicator of metastatic dissemination in uveal melanoma. Fresh or paraffin-embedded tumor tissue is most commonly used for current cytogenetic techniques for determining chromosome 3 status in uveal melanoma and often requires referral to an external specialist laboratory for analysis.


OBJECTIVE
To assess the chromogenic in situ hybridization assay for detecting chromosome 3 alterations using frozen tumor imprints and to compare the results obtained with those obtained by standard fluorescence in situ hybridization or single-nucleotide polymorphism array techniques.


METHODS
Chromogenic in situ hybridization was performed on 52 frozen uveal melanoma tumor imprints. The genetic status of 26 of the 52 cases had been determined previously by fluorescence in situ hybridization (group 1); the status of 26 cases had been determined using single-nucleotide polymorphism array (group 2).


RESULTS
Chromogenic in situ hybridization was successfully performed on 48 of 52 tumor imprints. Chromogenic in situ hybridization showed excellent agreement in all 24 cases determined by fluorescence in situ hybridization (100% concordance; κ = 1; P < .001; 95% confidence interval, 100%-100%), and disagreed in 4 of the 24 cases previously studied by single-nucleotide polymorphism array (83% concordance; κ = 0.67; P < .001; 95% confidence interval, 95%-39%). All 4 discordant cases were classified as disomic for chromosome 3 by chromogenic in situ hybridization and monosomic by SNP array. On histologic examination, the 4 discordant cases corresponded to 2 mixed cell tumors and 2 spindle cell tumors.


CONCLUSIONS
Chromogenic in situ hybridization using tumor imprints is a reliable technique for determining chromosome 3 status in uveal melanoma. Furthermore, it can also be easily integrated into a routine histopathology laboratory.
From the National Institute for Cellular Biotechnology, Dublin City University, Glasnevin, Dublin, Ireland (Dr Larkin); and the National Ophthalmic Pathology Laboratory of Ireland (Ms Gleeson and Dr Kennedy), the Research Foundation (Ms Gleeson and Dr Kennedy), and the Department of Ophthalmology (Mr Horgan), Royal Victoria Eye and Ear Hospital, Dublin, Ireland.
Grainne
G
Gleeson
Annemarie
A
Larkin
Noel
N
Horgan
Susan
S
Kennedy
D002893:Chromosomes, Human, Pair 3 / Q000235:genetics*; D004273:DNA, Neoplasm / Q000235:genetics; D006801:Humans; D017403:In Situ Hybridization / Q000379:methods*; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D008545:Melanoma / Q000175:diagnosis / Q000235:genetics*; D009006:Monosomy / Q000175:diagnosis* / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D015203:Reproducibility of Results; D012189:Retrospective Studies; D014604:Uveal Neoplasms / Q000175:diagnosis / Q000235:genetics*
D004273:DNA, Neoplasm