Incorporation of cytogenetic and molecular techniques in ocular pathology

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AbstractPurpose The roles of molecular techniques in ocular pathology are four‐fold: a) Understanding disease pathogenesis; b) diagnosis; c) prognosis; and d) predicting therapy response.Methods Examples of recent developments in molecular pathology in understanding the pathogenesis of tumours include the sonic hedgehog pathway in BCC; polyomavirus MCPyV in Merkel cell carcinoma; microsatellite instability in sebaceous carcinoma; fusion oncogenes in adenoid cystic carcinoma and mucoepidermoid carcinoma; and A20 gene deletions in conjunctival MALT lymphoma. Molecular techniques, such as IgH‐PCR and TCR‐PCR, are required regularly for the confirmation of the diagnosis of ocular B‐ and T‐cell lymphomas, respectively. In particular, IgH‐PCR is required to provide supportive evidence for the diagnosis of vitreoretinal lymphoma, when evaluating a diagnostic vitrectomy or a subretinal aspirate/chorioretinal biopsy.Results The main example in ocular oncology where molecular techniques are used for prognostication is uveal melanoma. The presence of monosomy 3 and polysomy 8 was initially detected using FISH. Techniques, which provide more detailed information, such as MLPA, aCGH, and GEP, have been introduced in various ocular oncology centres, with the molecular genetic data being incorporated with clinical and histomorphological features to provide individualized prognostic curves.Conclusion Advances have been made in some other malignancies in predicting tumour response to therapy. For many ocular malignancies, such a “magic bullet” has not yet been found; however, the principles of predicting “responders” and “non‐responders” and the potential targets will be discussed.