Genetic and histological heterogeneity in uveal melanoma: a peculiar case

Abstract

AbstractPurpose Intratumour heterogeneity of uveal melanoma (UM) has become a relevant issue in the era of sampling for prognostication purposes. We present the case of a UM consisting of two very distinct components.Methods A 53‐year‐old man was referred for an infero‐nasal, collar‐stud UM with associated retinal detachment in the right eye. On ultrasonography, the tumour measured 14 x 16mm, with a thickness of 11mm. The patient chose enucleation over other treatment options. The eye was examined morphologically, immunohistochemically and using multiplex ligation‐dependent probe amplification (MLPA).Results Histological sections demonstrated two distinct components: a pale basal part consisting of amelanotic epithelioid melanoma cells with extensive diffuse involvement of the ocular structures. In contrast, the apical part was heavily pigmented comprised only of spindle B cells. Interestingly, MLPA demonstrated complete chromosome 3 loss in the apical (spindle) region but only partial chromosome 3 deletion in the basal (epithelioid) part. Both areas showed polysomy 8. Conversely, immunohistochemistry showed more aggressive features in the basal part rather than in the apical part.Conclusion This case provides further evidence that there is heterogeneity in UM, and that a single intraocular biopsy may not be reliable for prognostication purposes.