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

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.

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.

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.

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.