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Purpose: To detect the presence of MYD88 L265P mutation in the aqueous humor of patients with cytologically proven vitreoretinal lymphoma., Methods: Eight consecutive patients with bilateral vitreoretinal lymphoma (16 eyes) were prospectively evaluated. Genomic DNA was extracted from aqueous samples after paracentesis and vitreous humor samples after diagnostic vitrectomy. MYD88 codon 265 mutation was investigated by both amplification-refractory mutation system polymerase chain reaction approach and pyrosequencing assay in the aqueous humor of all patients and in the vitreous of 6 patients. A control group of 8 age-matched patients with established diagnosis of noninfectious uveitis was also tested for the presence of MYD88 L265P mutation in the aqueous humor., Results: Eight patients (three men, five women) with mean age of 69.5 years (range 50-85 years) were considered. All the patients tested for MYD88 L265P in the vitreous (six) were positive, and this result was consistent with cytological examination in all samples but one. The MYD88 L265P mutation was found in the aqueous of 6 patients (75%), and in 3 of them, the mutation was present in both eyes. Results of MYD88 L265P mutation in aqueous and vitreous sample were consistent in 7 of the 8 eyes with available samples. The aqueous humor of the noninfectious uveitis control group was negative for the detection of MYD88 L265P mutation., Conclusion: MYD88 mutation was detected in the aqueous humor of 75% of patients with cytologically proven vitreoretinal lymphoma. This technique may be considered as an additional diagnostic tool in the detection of the disease.

Molecular therapies targeting HER2 are part of the established drug armamentarium in breast carcinoma. Now the ToGA trial, an international multicenter phase III clinical study, involving 24 countries globally, has shown that the anti-HER2 humanized monoclonal antibody Trastuzumab is effective in prolonging survival in HER2-positive carcinoma of the stomach and the gastroesophageal junction (GEJ). Similarly to breast carcinoma, >20% of gastric cancers show HER2 overexpression and/or amplification, and this percentage increases to 33% in GEJ tumors. Thus, as in breast carcinoma, pathologists are now asked to evaluate HER2 status in gastric carcinoma samples. As validated in the ToGA trial, the HER2 testing criteria that must be used in evaluating both gastric carcinoma biopsies and surgical specimens significantly differ from those routinely applied in breast carcinoma. The main variations with regard to the pattern of reactivity in HER2-expressing cells are as follows: the completeness of membrane staining is not a "conditio sine qua non" and the number of stained cells necessary to consider a case as positive is different. We must also take note of the much more frequent heterogeneity of HER2 positivity in gastric cancer compared with breast carcinoma and the less stringent correlation between HER2 amplification and protein overexpression that is observed in gastric carcinoma, where more than 20% of cases may carry HER2 amplification, although of low level, without HER2 expression. In these patients, in the ToGA trial, there was no apparent benefit from adding Trastuzumab to chemotherapy: for this reason the European Medicines Agency, while approving usage of Trastuzumab for metastatic adenocarcinoma treatment, indicated HER2 testing by immunohistochemistry as first evaluation assay, followed by fluorescence in situ hybridization in 2+ equivocal cases. HER2 testing in gastric carcinoma is a new field, opening several opportunities: for patients with gastric cancer, this is a new promising therapeutic option; for pathologists, strengthening our role in therapy selection and emphasizing our duty of providing accurate and reproducible HER2 testing results; for all interested in understanding the biology of gastric and GEJ cancer and in discovering new possible molecular therapy targets.