Uveal Melanoma with Histopathologic Intratumoral Heterogeneity Associated with Gene Expression Profile Discordance.

Purpose: To report a case of intratumoral gene expression profile discordance in a malignant uveal melanoma, associated with intratumoral heterogeneity based upon histopathologic features.

Methods: The clinical history, fundus findings, imaging and histopathologic features, and DecisionDx-UM gene expression profile results (Castle Biosciences, Inc., Phoenix, AZ, USA) of the tumor were reviewed.

Results: A trans-retinal fine-needle aspiration biopsy was performed for a thin, pigmented choroidal tumor in a 33-year-old man. Cells obtained from this biopsy were tested using the DecisionDx-UM gene expression profile test and the tumor was classified as class 1A. Cytology confirmed melanoma. The patient subsequently elected to undergo enucleation. On microscopic examination of the globe, the tumor was composed primarily of spindle B cells, but had a focal area composed of epithelioid cells. This portion of the tumor was subsequently tested and demonstrated a class 1B gene expression profile.

Conclusion: Intratumoral discordance in gene expression profile results has been described in uveal melanomas. Here we demonstrate that this discordance may be associated in some cases with intratumoral heterogeneity based upon histopathologic features.