Analysis of intraocular biopsies

Abstract

In this chapter, the importance of intraocular biopsies in the diagnosis/exclusion of ocular malignancies and prognostication is outlined. Despite improvements in ancillary studies in ophthalmology, intraocular biopsies are increasingly being performed in many ocular oncology centres. Experience is required in taking these biopsies, in their transport to the pathology laboratory, in their triaging and processing, and in their interpretation. To optimize the biopsy yield, well-tested and practical standard operational procedures for morphological, immunocytological and molecular genetic analyses are necessary. 'Tips and tricks' for the fixation and processing of intraocular tissue and fluid biopsies are provided. For example, a fixative such as Cytolyt or HOPE fixation is recommended for vitreous biopsies, allowing for all investigations to be performed, including DNA-based molecular genetic techniques, such as polymerase chain reaction used in clonality analysis in lymphoma diagnosis and in organism identification in endophthalmitis. Most solid tissue samples can be placed in buffered formalin, with the exception of those requiring RNA-based molecular techniques, here fresh tissue being preferable. The importance of incorporating data from all investigations and summarizing them as an integrated report is emphasized. The pitfalls of using any single test (e.g. a molecular genetic test) as a 'stand-alone' investigation are highlighted. Communication with relevant clinical information between surgeon and pathologist is essential at each stage: for sample delivery, for exclusion of differential diagnoses and for rapid result transmission. The current molecular genetic techniques for uveal melanoma prognostication are summarized, and how their data can be used for instigation of individualized management plans for patients discussed.