Marginal zone B-cell lymphoma: a retrospective immunophenotypic analysis.

BACKGROUND: Marginal zone B-cell lymphoma (MZL) comprises three related yet biologically distinct subtypes--splenic MZL (SMZL), nodal MZL (NMZL), and extranodal MZL of MALT type (MALT). In cases without adequate morphology, immunophenotypic characterization by flow cytometric immunophenotyping (FCI) relies heavily on exclusion of other low-grade lymphomas. We performed a retrospective review of FCI studies of MZL to search for immunophenotypes specific for MZL and its subtypes. We compared these to follicular lymphoma (FL) as we were specifically interested in differentiating MZL from CD10 negative FL. DESIGN: FCI findings for MZL and FL cases were reviewed. Statistical analysis of patterns and intensity of antigen expression [mean channel fluorescence (MCF)] were performed. RESULTS: Thirty-one cases of MZL (7 SMZL, 6 NMZL, 15 MALT, 3 MZL not otherwise specified) and 31 cases of FL were identified. All expressed CD19, CD20, and CD45. Thirty-two percent of MZL and 77% of FL expressed CD38. Expression of CD11c was seen in 57% of SMZL and 8% of other MZL (P < 0.01). Statistically significant differences in antigen expression between MZL and FL were seen for CD10, CD11c, and CD38. CD19 expression was significantly brighter in MZL (mean MCF of 455.3) than in FL (mean MCF of 166.9) (P < 0.001). MCF for isotype controls and CD20 were similar for FL and MZL. CONCLUSIONS: MZL expresses typical pan-B-cell antigens. Expression of CD11c is highly associated with SMZL. Levels of CD19 expression in conjunction with CD11c and CD38 expression can distinguish MZL from CD10 negative FL.

Nonfatal intravascular hemolysis in a pediatric patient after transfusion of a platelet unit with high-titer anti-A.

BACKGROUND: In the pediatric population, hemolysis after out-of-group platelet (PLT) transfusion is a potentially fatal event that is thought to be underrecognized. Group A patients transfused with group O single-donor PLTs (SDPs) with "high-titer" anti-A are at greatest risk for hemolysis. STUDY DESIGN AND METHODS: A clinical and serologic evaluation of a pediatric patient with hemolysis of initially unknown etiology was conducted. Retrospective testing for anti-A titer of an admission sample and a transfused group O SDP was performed. RESULTS: The group A patient (previously group O) was found to have a history of engrafted major ABO-mismatched hematopoietic peripheral blood progenitor cell transplant (HPBPCT). Immune-mediated intravascular hemolysis with a delayed presentation was determined. Testing identified passive anti-A in the patient's plasma and high-titer anti-A (IgG 4096, IgM 256) in the group O SDP unit. CONCLUSION: Hemolysis after out-of-group SDP transfusion may be delayed in presentation and, thus, clinically unrecognized. When evaluating these cases, the limitations of routine type and screen for detection of passive anti-A must be considered. Group A individuals with a history of engrafted major ABO-mismatched HPBPCT potentially have increased susceptibility to hemolysis from group O SDP transfusion due to their lack of tissue and soluble A antigen.

Multicenter beta trial of the GeneXpert enterovirus assay.

The GeneXpert Dx system (Cepheid, Sunnyvale, CA) is a fully integrated and automated nucleic acid sample preparation, amplification, and real-time detection system. It consists of an instrument, a personal computer, and disposable fluidic cartridges. The analytical sensitivity and specificity of the GeneXpert enterovirus assay (GXEA) were determined with a panel of 63 different enterovirus serotypes and 24 other microorganisms, respectively. The potential for blood, hemoglobin, white blood cells, and excess protein to interfere with the assay was also assessed. The performance parameters of the GXEA were determined at three sites with 102 cerebrospinal fluid (CSF) samples obtained from patients with suspected meningitis. All samples were tested for enterovirus RNA with locally developed reverse transcription-PCR (RT-PCR) assays at the trial sites and with a seminested RT-PCR and an analyte-specific reagent (Cepheid) at a reference laboratory. The 5' nontranslated region was the target for all of the PCR assays except the seminested RT-PCR, which amplified a VP1 sequence. The VP1 amplicon was sequenced to identify the enterovirus types. Consensus reference laboratory RT-PCR results were used to classify cases of enteroviral meningitis. The GXEA detected all of the enterovirus serotypes and none of the other microorganisms tested except rhinovirus 16. The assay was unaffected by moderate amounts of blood or blood components. Thirty-six (35%) of the CSF samples tested had at least one positive PCR result. Eleven different enterovirus serotypes were identified in the positive samples. The GXEA had a sensitivity of 97.1% (95% confidence interval [CI], 84.7 to 99.9%) and a specificity of 100% (95% CI, 94.6 to 100%) for the diagnosis of enteroviral meningitis.