1072PD - Mutational profiling through exome sequencing along with MYD88 L265P analysis could facilitate the diagnosis of vitreoretinal lymphoma

Vitreoretinal lymphoma (VRL), previously known as intraocular lymphoma, is a rare form of malignancy. Although the disease is highly aggressive with elevated mortality rate, there are no standard of differential diagnosis from posterior uveitis when the amount of vitreous is so limited. MYD88 L265P mutation is reported to be identified in the vitreous of approximately 70% of patients with VRL. In view of the need of establishing new procedures to support the diagnosis of VRL, we explored the exome of lymphoma cells and the prevalence of MYD88 L265P mutation in Korean VRL patients. We performed the exome sequencing of vitreous of 8 patients with matched germline blood or buccal swab samples. The patients suspicious of VRL and underwent standard vitrectomy between July 2016 and September 2018 were enrolled. Sequencing data were analyzed and compared with those of CNS lymphoma. We established real-time PCR system for MYD88 L265P mutations. Vitreous of eight patients and an additional patient were subjected to the test. Approximately 400 somatic mutations were identified for each patient through whole exome sequencing. Most frequetly mutated gene was MYD88. Previously reported frequently mutated genes such as PIM1 and CD79B were found to be mutated. Mutational profile of VRL showed similarity to that of PCNSL or DLBCL. Most VRL showed complex karyotype. The detection limit of MYD88 L265P real-time PCR was approximately 2%, and 5 out of 9 patients had MYD88 L265P mutation. MYD88 L265P real-time PCR could be a good diagnostic tool for the patients with VRL harboring MYD88 L265P mutation. We concluded that exome or gene panel testing of VRL and confirmation of the presence of a number of somatic mutation and mutation profile may facilitate the diagnosis of VRL in a subset of patients. The authors. Has not received any funding. All authors have declared no conflicts of interest.