[Diffuse malignant melanoma of the uvea. A clinico-histopathologic study of 39 patients]

Abstract

Background: Focal malignant melanomas involving only the iris have a very good prognosis. Involvement of the iris and/or diffuse growth makes the prognosis worse. The prognostic parameters of diffusely growing malignant anterior uveal melanomas are analysed.

Patients and methods: From 1981-1995 serial sections of 39 eyes, 23 women and 16 men, of diffusely growing malignant anterior uveal melanomas were histologically examined. Patients were between 9 and 80 years old (median 56 years). Follow-up was between 2 months and 15 years. At the end of the study, 13 patients had died from metastasis, all showed involvement beyond the iris. Four patients died from other causes.

Results: The 39 diffuse malignant melanomas were categorized into 10 affecting only the iris, 18 iris and ciliary body and 11 involving iris, ciliary body and choroid. 14 spindle-cell, 23 mixed-cell and 2 epithelioid-cell tumors were identified. We observed between 0 and 4 mitoses in 40 high-power fields. Only 4 melanomas showed more than 100 tumor-infiltrating lymphocytes in 20 high-power fields. Nine tumors showed extra-scleral spread, nine displayed vascular networks. Univariate Kaplan-Meier survival curves showed as significant prognostic factors: localization in the iris only (p = 0.0008), spindle cell type (p = 0.0002) and absence of vascular networks (p = 0.01). This was confirmed by multivariate Cox analysis.

Conclusion: Patients with diffuse malignant melanoma confined to the iris alone have a good prognosis for survival. Diffuse tumor cell spread can be diagnosed at the slitlamp with high magnification. Conservative follow-up is acceptable, as long as ciliary body involvement is ruled out. Eye with medically uncontrollable secondary glaucoma should be enucleated. Anti-glaucoma filtering procedures are contraindicated because of the danger of extraocular spreading malignant cells.