There is evidence of a slight increase in malignant lymphoma among rheumatoid arthritis(RA)patients receiving methotrexate( MTX). Increased rates of lymphoma have been attributed to reactivation of the Epstein-Barr virus(EBV). A 72-yearold woman was admitted to our hospital for generalized lymph adenopathy. She suffered from RA and has been treated with MTX for 7 years; the total amount of MTX received was around 2, 700 mg. The cervical lymph node revealed a diffuse proliferation of large atypical lymphocytes. An immunophenotype revealed CD10+, CD19+, CD20+, and k+. The chromosome analysis showed a complex abnormality containing t(14;18)(q32;q21). The tumor cells were positive for EBV sequences by in situ hybridization(ISH). A rituximab containing regimen was effective, but a systemic relapse occurred 4 years later. The biopsied sample was diagnosed as diffuse large B-cell lymphoma. FISH analysis revealed positive for t(14;18)(q32;q21), however, EBV was negative using ISH. In general, the concurrence of t(14;18)(q32;q21)and EBV in the B-cell lymphoma is rare. In addition, the negative change in EBV in the relapsed lymphoma cells revealed a quite rare phenomenon.

Mutation of the KRAS gene in patients with metastatic colorectal cancer(mCRC)has been established as a predictive marker of poor response to anti-EGFR cetuximab. The Japanese Society of Medical Oncology recommends that the KRAS mutation status at codon 12 and codon 13 should be genotyped by direct-sequencing or allele-specific PCR. In this study, we tested the point mutation of codon 12 and 13 in the KRAS gene by Luminex(xMAP)flow cytometry with sequence-specific oligonucleotide probes for 39 out of 64 unresectable mCRC patients enrolled from Sep 2008 to Oct 2009, who were administered cetuximab in combination with irinotecan(CPT-11)as third-line therapy. We retrospectively analyzed the relationship between KRAS mutation status and responses to combination therapy. Mutations in the KRAS gene were detected in 38. 5% of cases(codon12: 73%, codon 13: 27%), and the median follow-up time was 8. 2 months(range, 1. 4-15. 2 months). The response rates for patients with KRAS wild-type and patients with KRAS mutations were 33. 3%(95%CI 14. 5-52. 2%)and 0%(p=0. 015); the disease control rates were 75%(95%CI 57. 7-92. 3%)and 40%(95%CI, 15. 2-64. 8%; p=0. 044); the median TTF was 7 months(95%CI 4. 6-9. 3)and 2. 3 months(95%CI 1. 3-3. 2; p=0. 0007), and the median OS was 12. 9 months(95%CI 6. 7-19. 1)and 10. 8 months(95%CI 5. 0-16. 7; p=0. 15), respectively. Therefore, we concluded that the KRAS mutation in mCRC is a predictive factor for the lack of response to combination therapy with cetuximab plus CPT- 11, as reported in previous clinical studies.