Extra-Scleral Spread of Uveal Melanoma - Characteristics, Comparisons and Clinical Correlations

Abstract

Purpose:: To describe mortality and histopathological features of uveal melanoma with extra-scleral extension and to compare these with a matched group of tumours with no spread.

Methods:: Patients enucleated for uveal melanoma with extra-ocular tumour extension were compared with patients without extra-scleral spread, using the Χ² test. Baseline variables investigated were: basal tumour diameter; anterior tumour extension; tumour cell type; closed connective tissue loops; mitotic rate, and route of extraocular extension. Patients were prospectively notified to the National Health Service Cancer Registry, which automatically notified us of the date and cause of any deaths. Survival according to risk factors was investigated using Kaplan-Meier analysis and the logrank test.

Results:: The study sample comprised 107 enucleated eyes with extraocular extension and 108 eyes without this feature. The routes of extraocular extension were: vortex vein - 20.1%, direct trans-scleral - 36.3%, other vascular - 13.7%, trabecular meshwork - 18.5%, neural - 8% and optic nerve - 3.2%. Of these, 78.5% had epithelioid cell type present; closed connective tissue loops were found in 71.0% of cases and the mean number of mitotic figures per 40 high power fields was 6.4. 47.6% of patients had died at the time of reporting, 81.6% of these due to confirmed ocular metastasis. The presence of both closed loops and epithelioid cells was associated with extraocular extension (X² =15.54, d.f.=1, P<0.001 and X² = 14.59, d.f.=1, P<0.001 respectively). A significantly higher proportion of patients with extra-scleral spread had died from confirmed distant metastasis than in the group without (X² =10.27, d.f.=1, P≈0.001).

Conclusions:: The commonest routes for extraocular spread of uveal melanoma were direct trans-scleral extension and growth through or around a vortex vein. All modes of spread were associated with death from metastatic disease. The presence of epithelioid cells and closed connective tissue loops are strongly associated with extraocular extension.

Keywords: melanoma • pathology: human • oncology