Intraocular collision tumour: case report and literature review

"Collision" tumours consist of different neoplasms coexisting within a single lesion. Whilst quite common in the skin, the gastrointestional tract, and the ovaries, intraocular collision tumours are exceedingly rare. We describe an exceptional case of a combined uveal melanoma and intraocular plasmacytoma.

Observational case report. A 61-year-old woman underwent enucleation for rubeotic glaucoma and cells in the anterior chamber after proton-beam radiotherapy of a cilio-choroidal melanoma of the right eye. Examination of the enucleated eye was performed with immunohistochemistry, multiplex ligation dependent probe amplification (MLPA), and polymerase chain reaction (PCR) for immunoglobulin heavy- and light-chain gene rearrangements. A review of the literature on ocular collision tumours and uveal involvement by plasma cell neoplasms was also performed.

Morphological, immunophenotypical, and genotypical examination of the tumour revealed the co-existence of both a melanoma and a plasmacytoma within the choroid and ciliary body. The glaucoma was caused by extensive infiltration of the iris and trabecular meshwork by the plasmacytoma cells. Review of the literature revealed only four collision tumours involving the eyelid and three involving the choroid. All three intraocular collision tumours consisted of uveal melanoma and choroidal non-Hodgkin lymphoma. Uveal involvement by plasma cell neoplasms is also extremely rare, with only six reported cases.

This is the first documented intraocular collision tumour consisting of a uveal melanoma and isolated plasmacytoma. If a patient presents with 'uveitis' after proton-beam radiotherapy of a cilio-choroidal melanoma, there may be scope for performing biopsies to determine whether the lymphoid infiltrate is reactive or neoplastic.