It has been recently hypothesized that the hepatitis C virus (HCV) might be involved in the pathogenesis of malignant B-cell non-Hodgkin's lymphomas (NHL). On the basis of this observation we sought to determine the prevalence of HCV infection in the patients affected by B- cell NHL and extended our analysis to all the patients affected by lymphoproliferation disorders seen at our institution in the last 30 months. Five hundred and thirty-seven unselected, consecutive patients were studied. HCV infection was investigated through detection of anti- HCV antibodies and HCV-RNA. HCV genotyping was performed on HCV-RNA positive specimens. The risk of being infected by HCV was compared with that of the general population of our area. Among all lymphoproliferative disorders, the prevalence and the relative risk (RR) of being infected by HCV were increased only among B-cell NHL (9%; RR 3.24; p < .0001). Among these, a strong prevalence of HCV was found only in the subgroup of immunocytomas (30%; RR 10.27; P < .0001), while other histotypes were associated with it only occasionally. Because HCV- positive lymphomas clinically behave as essential mixed cryoglobulinemia (EMC), the close association between HCV infection and EMC is confirmed, and evidence is provided that the pathological substrate of EMC corresponds to the immunocytoma. HCV genomic sequences were found in 84% of patients analyzed. Viral genotypes were those more frequent in our area.

A high prevalence of chronic hepatitis C virus (HCV) infection has recently been shown in a subset of B-cell non-Hodgkin's lymphomas, most of which belong to the lymphoplasmacytoid lymphoma/immunocytoma subtype and are characterized by the production of a monoclonal IgM cryoglobulin with rheumatoid factor activity. To better define the stage of differentiation of the malignant B cell and to investigate the role of chronic antigen stimulation in the pathogenesis of the HCV-associated immunocytomas, we analyzed the variable (V) region gene repertoire in 16 cases with this type of tumor. The lymphoma-derived V gene sequences were successfully determined in 8 cases; 5 of them expressed the 51p1 VH gene in combination with the kv325 VL gene. Moreover, a monoclonal 51p1-expressing B-cell population was detected in 4 of the remaining immunocytomas by an allele-specific Ig gene fingerprinting assay, indicating that HCV-associated immunocytomas represent clonal proliferations of a highly selected B-cell population. Somatic mutations and intraclonal diversity were observed in all of the lymphoma V genes, and clonally related IgM and IgG VH transcripts indicative of isotype switching were present in one case. These findings are consistent with an antigen-driven process and support a role for chronic antigen stimulation in the growth and clonal evolution of HCV-associated immunocytomas.

Reactivation of hepatitis B virus in patients receiving chemotherapy for non-Hodgkin's lymphoma (NHL) may give rise to hepatitis, hepatic failure and death, and prevent further chemotherapy. We report four patients with NHL in whom hepatitis flare-up was observed after two (three patients) and six (one patient) cycles of chemotherapy. After spontaneous recovery, they were treated with Lamivudine (100 mg/day), which enabled completion of chemotherapy without further hepatitis B reactivation. In one patient, high-dose chemotherapy and autologous stem cell transplantation was also performed. These data suggest a possible role for Lamivudine in preventing hepatitis B reactivation during chemotherapy administration to chronic carriers of the hepatitis B virus. Moreover, it enabled the completion of both standard and high-dose chemotherapy in patients with previous hepatitis B reactivation.

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