Variation of monosomy 3 status within uveal melanoma.

CONTEXT: Determining the most significant prognostic variables in uveal melanoma is important for stratifying patients for metastasis surveillance and possible initiation of chemotherapy or immunotherapy. Monosomy 3, one such variable, can be determined using fluorescence in situ hybridization, either on enucleated samples, fine-needle aspiration biopsy, or tumor sample obtained by vitrector.

OBJECTIVE

To evaluate possible regional discordance in chromosome 3 by sites likely to be sampled by different biopsy methods.

DESIGN

Eighteen consecutive patients with uveal melanoma who underwent primary enucleation were studied. Representative paraffin blocks were selected based on review of hematoxylin-eosin stained sections, and the apex and base of each tumor was demarcated. Unstained paraffin sections, 4 mum in thickness, were prepared, and fluorescence in situ hybridization, looking for monosomy 3, was performed. The chromosomal analysis was also correlated with histologic evaluation for melanoma cell type (spindle vs epithelioid cell), ciliary body involvement, presence of positive periodic acid-Schiff vascular mimicry patterns, scleral or extrascleral spread and size. One case was excluded because of necrosis.

RESULTS

Ten of the 17 remaining cases (59%) demonstrated monosomy 3 (in either the base or both base and apex of the tumor) with 7 cases (41%) showing disomy. Seven cases (70%) with monosomy 3 demonstrated this in both the apex and the base locations, whereas 3 cases (30%) showed monosomy in one location only (always at the base). Fourteen of the 17 cases (82%) revealed concordance in chromosome 3-monosomy 3 (7 of 14, 50%) or chromosome 3-disomy 3 (7 of 14, 50%). All 3 discordant cases demonstrated the monosomy 3 at the base with disomy at the apex. Lack of concordance between the base and apex did not correlate with melanoma cell type.

CONCLUSIONS

Prognostic variables are important in management of neoplasms, and this study points out that the site of tissue biopsy for prognostication in uveal melanoma could affect the results obtained, at least for the presence of monosomy 3.