“De novo” Appearance of a Choroidal Melanoma During 5 Yearsʼ Follow-up for CHRPE

Introduction

Uveal melanoma, the most common primary intraocular malignancy in adults, has an incidence of about 6 new cases per million per year in Caucasians [1], [2]. The choroid is the most frequent localization (85 – 91%), whereas the ciliary body or the iris are affected in only 9 – 15% of cases. Its pathogenesis is not yet clearly understood. Relative risk factors are a fair skin, light eye color, ocular or oculodermal melanocytosis, and the presence of a cutaneous, iris, or choroidal nevus. It is associated with BAP1 or BRCA1 mutation carriers [2].

The question whether posterior uveal melanomas arise from preexisting nevi, or “de novo”, has been an object of controversy, as the appearance and initial evolution of this rare fundus tumor occur asymptomatically, invisible to the patient. The first “proof” of the possible malignant transformation of nevi into melanoma was provided in 1967 by Yanoff and Zimmermann, who published a histopathological study on 100 uveal melanomas, in 73 of which they had observed the presence of “nevus cells” at the base of the tumor [3]. They concluded that “most malignant melanomas arise from pre-existing nevi”. However, their conclusion lost its basis when Albert, in 1974, described “nevus-like” structures in experimental choroidal melanomas in laboratory animals [4], advancing the concept that melanomas also arise “de novo”. Numerous studies have investigated the malignant transformation of presumed choroidal nevi and its risk factors [5], [6]. However, documented proof of a “de novo” genesis of a choroidal melanoma is rare [7], [8].

Growth of malignant tumors is exponential, and tumor doubling times (TDT) of choroidal melanomas, managed with observation, were observed to vary from 292 to 128 days in fusiform and mixed-cell melanomas, respectively, with the former and latter corresponding relatively more likely to “nevus” and “de novo” originating melanomas [9].

The aim of this report is to present the exceptional case of a “de novo” choroidal melanoma whose appearance and exponential growth were incidentally documented on serial color fundus pictures while monitoring the patient for another condition.

Publication History

Received: 06 October 2021

Accepted: 27 February 2022

Article published online:
26 April 2022

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