Toxin A variant strains of C. difficile cause serious disease and are undetectable in clinical laboratories that use only toxin A immunoassays for C. difficile testing.
Few studies have characterized or compared the pathologic features of bone marrow involvement by extranodal (EMZL), splenic (SMZL), and nodal marginal zone lymphoma (NMZL). We evaluated 45 bone marrow biopsy specimens from 39 patients with marginal zone lymphomas. As previously reported, bone marrow involvement was frequent (100%) in patients with SMZL. We also identified lymphoma involving bone marrow in 11 (44%) of 25 patients with EMZL and 1 of 2 patients with NMZL. The patterns of infiltration were mixed in all groups; however, the extent of involvement was greater in SMZL than in EMZL. In addition, germinal centers were present in bone marrow biopsy specimens involved by lymphoma in 4 patients with SMZL. Intrasinusoidal infiltration was common (10/12 [83%]) and prominent in patients with bone marrow involvement by SMZL, but was not invariably present. Intrasinusoidal infiltration of the bone marrow also was not specific for SMZL since similar infiltrates, although subtle, also were found in patients with other small B-cell lymphoproliferative disorders, including 6 (55%) of 11 patients whose bone marrow samples were infiltrated by EMZL.
Targeted therapy with conjugated and unconjugated monoclonal antibodies for non-Hodgkin's lymphoma has revolutionized the approach to this disease. The efficacy and low toxicity of these agents have allowed introduction of this strategy in the early stages of therapy. Longer follow-up is needed before validating the safety of these agents. Since monoclonal antibodies are being given as front-line therapy, it is important to identify all potential adverse events. We report a case of secondary acute myelogenous leukemia (AML) with 11q23 cytogenetic abnormality and mixed lymphoid leukemia (MLL) gene expression in a patient treated with Y90 labeled anti-CD20 antibody (Zevalin). The patient was not exposed to topoisomerase II inhibitors. Our observations suggest a relationship between 11q23 leukemia and radioimmunotherapy (RAIT) and further studies are needed.
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