Abstract
Purpose: :
To determine status of chromosome 3 and 8q and c-myc amplification using fluorescence in situ hybridization (FISH) on hepatic metastatic lesions of primary uveal melanoma.
Methods: :
10 patients with uveal melanoma with liver biopsy confirmed hepatic metastasis. Representative paraffin blocks were selected based on review of hematoxylin and eosin stained sections. FISH was performed for detection of monosomy 3 and amplification at the 8q24 MYC locus using standard methods. The tricolor CEP8/IGH/MYC probe (Abbott Molecular, Des Plains, IL) and the Urovysion probe consisting of CEP 3, CEP 7, CEP 17, and 9P21 probes (Abbott Molecular) were used for detection of monosomy 3 and amplification of the 8q24 MYC locus. Two hundred interphase cells were then scored to determine the percentage of signals. For the determination of 8q24/MYC amplification, only cells having at least two 8q24 signals were counted. For the assessment of monosomic states for Urovysion 3, to control for truncation artifact, only tumor cell nuclei with at least two CEP7 signals were counted. The CEP3/CEP7 ratio was then calculated and the loss of CEP3/monosomy 3 was determined to be present if the CEP3/CEP7 ratio was < 0.7. CEP8 was reported as aneusomic when the tumor averaged >3 chromsomeome 8 per cell. C myc amplification was reported as present when the ratio of Cmyc probe and CEP 8 probe was >2.0.
Results: :
Hepatic metastasis was confirmed in each case by liver biopsy. FISH analysis revealed chromosome 3 monosomy in 5 of the 8 cases that could be satisfactorily evaluated. Of the 3 cases with normal complement of chromosome 3, aneusomy of chromosome 8 was observed in 2 cases (1 case, not enough tissue). Additional evaluation of chromosomal region 8q with c-myc amplification in 9 samples, revealed amplification in 5 samples. In a single case where the primary tumor was treated by enucleation, the chromosomal monosomy 3 and aneusomy of chromosme 8 were present both in the primary tumor and its hepatic metastatic lesion.
Conclusions: :
The presence of cytogenetic changes within the metatstatic lesions confirms that chromosome 3 monsomy and aneusomy of chromosome 8 are not just markers of metastatic potential of the primary tumor but are present within the hepatic metastatic lesions.
Keywords: melanoma • genetics • pathobiology