Purpose:
To study the status of chromosome 3 in choroidal melanomas showing slow increase in thickness without a concomitant increase in basal diameter.
Methods:
Ten cases of choroidal melanoma with ultrasonographic evidence of increased thickness without photographic evidence of increased basal diameter were treated with Iodine-125 plaque radiotherapy from November 2005 to January 2009. Fine-needle aspiration biopsy for cytogenetic evaluation was performed at the time of plaque radiotherapy using a transvitreal approach with a 27-gauge needle for post-equatorial tumors and a direct transscleral approach with a 30-gauge needle for pre-equatorial tumors.
Results:
The mean age at presentation was 55 years (range, 39-74 years) and 3 patients were male. Mean maximal basal diameter was 9 mm (range, 7-12 mm) and mean thickness was 2.3 mm (range, 1.5-3.9 mm) at initial visit. Overlying orange pigment and associated subretinal fluid were absent in all cases. After a mean observation period of 56 months (range, 6-165 months), there was a mean increase in thickness of 0.7 mm (range, 0.2-1 mm) without concomitant increase in basal diameter and tumor thickness was greater than 2 mm in 9 cases (90%). Subretinal fluid had developed in 5 cases and new symptoms in one case. All tumors were found to have disomy of chromosome 3 on cytogenetic evaluation. There were no instances of local tumor recurrence or distant metastasis following plaque radiotherapy during a mean follow-up of 29 months (range, 9-51 months).
Conclusions:
Presumed choroidal melanomas showing isolated and slow increase in thickness without concomitant increase in basal diameter are most often associated with disomy of chromosome 3 and excellent life prognosis.
Keywords: melanoma • uvea • genetics