Abstract
Purpose: :
To determine if the prognostic value of monosomy 3 testing in fine needle aspiration biopsies (FNAB) of choroidal melanoma can be improved by the inclusion of fluorescent probes specific for the subtelomeric regions of chromosome 6pq.
Methods: :
In patients clinically diagnosed with choroidal melanoma, FNAB was obtained at the time of radioactive Iodine-125 plaque placement. Slide smears of aspirates were sequentially probed for the subtelomeric regions of chromosome 6pq and the centromeric region of chromosome 3 and scored for the number of fluorescent signals in up to 300 nuclei per smear. Results were compared with high density mapping array findings.
Results: :
Technique of serial serial probing was feasible for samples. Results included patients with monosomy 3, 6p-gain, monosomy 3 and 6p-gain, monosomy 3 and 6q-loss, and normal signal pattern for both chromosomes. In a case where monosomy 3 and 6p-gain were detected concurrently, the aberrations were found to occur in the same nuclei and did not exist as two separate cell populations. Additionally, positive findings of 6p-gain in the absence of monosomy 3 were determined for at least two tumors.
Conclusions: :
The inclusion of chromosome 6 testing allows for a positive finding for the presence of tumor in FISH-probed aspirates in which monosomy 3 is not detected. This provides better prognostic information for tumors with lower likelihood of metastatic outcome. The combined use of FISH probes for the centromeric region of chromosome 3 and the subtelomeric regions of 6pq can identify the homogeneity in tumors that contain hybrid monosomy 3 and 6p-gain signal pattern that microarrays cannot address. Additionally, the use of these combined probes reduces the number of tumor samples that are found to have uninformative FISH results.
Keywords: melanoma • oncology