Complete ring melanoma of the choroid.

Background: Ring melanoma of the uvea is a term generally applied to elongated, circumferentially oriented malignant melanomas of the iris and ciliary body; a complete ring melanoma involving almost exclusively the choroid is extremely uncommon.

Methods: The authors present a case report and clinicopathologic correlation of complete ring melanoma of choroid managed by enucleation.

Results: A 74-year-old woman was found to have a diffuse, melanotic thickening of the midzonal to peripheral choroid circumferentially for 360 degrees and an associated subtotal serous retinal detachment with shifting subretinal fluid in her left eye. The thickest portion of the mass measured only 2.3 mm by ultrasound biometry. The eye was enucleated, and histopathologic analysis confirmed a diffuse malignant melanoma composed predominantly of spindle B cells.

Conclusions: A complete ring melanoma of the choroid is a rare and unusual variant of diffuse uveal malignant melanoma. The pertinent differential diagnosis of choroidal ring melanoma includes diffuse choroidal melanocytoma, choroidal melanocytosis associated with ocular melanocytosis, bilateral diffuse uveal melanocytic proliferation associated with systemic carcinoma, and diffuse uveal lymphocytic infiltration.