Significant Variability in the Identification and Reporting of Band Neutrophils by Participants Enrolled in the College of American Pathologists Proficiency Testing Program: Time for a Change.

CONTEXT.­: Increased band neutrophils in blood smear differential counts ("bandemia") are entrenched in medicine as a flag for sepsis. However, laboratory hematology experts have long advocated for discontinuation of reporting bands separately from segmented neutrophils because of poor sensitivity and specificity, poor interobserver agreement, and availability of alternative biomarkers for sepsis. OBJECTIVE.­: To describe band neutrophil reporting practices and reproducibility of band classification among laboratories participating in the College of American Pathologists (CAP) proficiency testing (PT) program. DESIGN.­: A survey questionnaire was distributed to hematology PT participants. A subsequent morphologic challenge included 12 preselected cell identifications of segmented neutrophils, bands, and metamyelocytes, and a 100-cell manual differential count of a digitally scanned blood smear. RESULTS.­: Among laboratories that reported manual differentials, most respondents reported bands (4554 of 5268; 86.4%). Only 3222 of 4412 respondents (73.0%) provided band reference ranges. Though participants classified "easy" band neutrophils well (78.0%-98.3%), categorization of cell identifications for "moderate" and "difficult" bands was poor (3.1%-39.0% of laboratories), with classification instead as segmented neutrophils. This pattern was seen regardless of laboratory demographic characteristics. Marked variability in band counts was observed on the 100-cell differential count for both CAP PT participants and CAP Hematology and Clinical Microscopy Committee (HCMC) members (coefficients of variation, 55.8% and 32.9%, respectively). Variability was significantly improved when segmented and band neutrophils were grouped together (coefficients of variation, 6.2% and 5.0%, respectively). CONCLUSIONS.­: Most CAP PT-participating laboratories report band counts, many without reference ranges. The survey confirms significant interlaboratory variability of band enumeration when bands are separately identified from segmented neutrophils. This study reaffirms the CAP Hematology and Clinical Microscopy Committee's strong recommendation to group segmented and band neutrophils together in manual differential counts.

Bone marrow involvement in patients with posttransplant lymphoproliferative disorders: incidence and prognostic factors.

Posttransplant lymphoproliferative disorders are classified as monomorphic, polymorphic, early lesions, or Hodgkin lymphoma type. Staging bone marrow examination is recommended in posttransplant lymphoproliferative disorder patients; however, information regarding bone marrow involvement in these disorders, especially as related to the posttransplant lymphoproliferative disorder subtype, is scarce. We reviewed the clinicopathologic features of 72 posttransplant lymphoproliferative disorder cases to determine the frequency of bone marrow involvement by various subtypes of posttransplant lymphoproliferative disorder, the clinical features of patients with and without bone marrow involvement, and their outcome. We also compared the incidence of bone marrow involvement of monomorphic posttransplant lymphoproliferative disorder (diffuse large B-cell lymphoma) with de novo diffuse large B-cell lymphoma (in both immunocompetent and HIV+ patients), and assessed the utility of various hematologic and serologic parameters as predictors of bone marrow involvement. Bone marrow involvement was seen in 23.5% of monomorphic posttransplant lymphoproliferative disorders and 15.7% of polymorphic posttransplant lymphoproliferative disorders, and the detection of bone marrow involvement on staging bone marrow biopsy upstaged 42% of monomorphic posttransplant lymphoproliferative disorders and 100% of polymorphic posttransplant lymphoproliferative disorders. Although bone marrow involvement appeared independent of patient age, organ transplanted, Epstein-Barr virus status, interval from transplantation to posttransplant lymphoproliferative disorder, or involvement of the grafted organ, it was significantly more frequent in cases without extranodal involvement; and it was associated with a significantly shorter survival. The incidence of bone marrow involvement in monomorphic posttransplant lymphoproliferative disorder (diffuse large B-cell lymphoma) was similar to that in HIV-associated diffuse large B-cell lymphoma, but higher than that in immunocompetent diffuse large B-cell lymphoma cases. No individual hematologic and serologic parameter was predictive of bone marrow involvement; however, the combination of elevated lactate dehydrogenase (>225 U/L) and decreased hemoglobin (<10 g/DL) can be used as a sensitive screening tool in determining which patients should proceed to bone marrow staging biopsy.

The clinicopathologic spectrum of posttransplantation lymphoproliferative disorders.

CONTEXT: Posttransplantation lymphoproliferative disorders (PTLDs) are a heterogeneous group of lymphoid proliferations occurring in the setting of solid organ or bone marrow transplantation. They show a clinical, morphologic, and molecular genetic spectrum ranging from reactive polyclonal lesions to frank lymphomas. The close association with Epstein-Barr virus has been established and the pathogenetic role of this virus is becoming better understood. Although they are relatively uncommon, PTLDs are a significant cause of morbidity and mortality in transplant patients. OBJECTIVE: To review the incidence, risk factors, clinical features, pathogenesis, and classification of PTLDs. DATA SOURCES: We reviewed relevant articles indexed in PubMed (National Library of Medicine), with emphasis on more recent studies. The classification of PTLDs is based on the most current World Health Organization classification text. CONCLUSIONS: Posttransplantation lymphoproliferative disorders are a heterogeneous group of disorders showing a wide clinical and morphologic spectrum. Although relatively uncommon, PTLDs represent a serious complication after transplantation. Many risk factors for PTLD are well established, including transplanted organ, age at transplant, and Epstein-Barr virus seronegativity at transplant. However, other factors have been implicated and still require additional examination. Recent studies are shedding some light on the pathogenesis of PTLDs and defining relevant pathways related to Epstein-Barr virus. As the pathogenesis of PTLDs is further elucidated, the classification of PTLDs will most likely evolve.

Expression of inhibitory receptor ILT3 on neoplastic B cells is associated with lymphoid tissue involvement in chronic lymphocytic leukemia.

T cell responses against leukemia-associated antigens have been reported in chronic lymphocytic leukemia (CLL). However, the relentless accumulation of CLL B cells in some patients indicates that anti-tumor immune responses are inefficient. Inhibitory receptors from the Ig-like transcript (ILT) family, such as ILT3 and ILT4, are crucial to the tolerogenic activity of antigen presenting cells. In this study, we examined the expression of ILT3 on CD5+ B cells obtained from 47 patients with CLL. Using flow cytometry and RT-PCR, we found that B CLL cells from 23 of 47 patients expressed ILT3 protein and mature ILT3 mRNA. ILT3 protein and mRNA were not found in normal B cells obtained from donors without CLL. Expression of ILT4 in normal and B CLL cells showed a pattern similar to ILT3. The frequency of ILT3 positive CLL B cells was higher in patients with lymphoid tissue involvement, suggesting that ILT3 may have prognostic value in CLL. Our findings indicate that expression of ILT3 and ILT4 on CLL B cells represents a phenotypic abnormality that may play a role in tolerization of tumor-specific T cells.

Pediatric ALK+ anaplastic large cell lymphoma with t(3;8)(q26.2;q24) translocation and c-myc rearrangement terminating in a leukemic phase.

Pediatric ALK-positive anaplastic large cell lymphoma (ALK+ ALCL) is usually associated with a favorable prognosis. ALK+ ALCL associated with a leukemic phase is uncommon, but has been associated with an aggressive clinical course and unfavorable prognosis. Overexpression of c-myc has been shown to be a consistent finding in ALK+, but not ALK-negative ALCL (ALK- ALCL), and the c-myc gene is considered a downstream target of deregulated ALK signaling. We describe a pediatric ALK+ ALCL with a leukemic phase at relapse. Similar to other rare cases described in the literature, it followed an aggressive clinical course despite multiple regimens of chemotherapy and bone marrow transplantation. Lymphoma cells showed aberrant ALK expression and c-myc overexpression. In addition to the characteristic t(2;5)(p23;q35) translocation, a t(3;8)(q26.2;q24) translocation was also present, and c-myc gene rearrangement was confirmed by FISH analysis. The findings in this case demonstrate the association of peripheral blood leukemic involvement and aggressive clinical course, and suggest that other factors, such as c-myc rearrangement, may be responsible for the aggressive clinical behavior in ALK+ ALCL.

Development of hairy cell leukemia in a patient after cardiac transplantation.

Post-transplant lymphoproliferative disorders (PTLDs) are well-recognized complications of bone marrow and solid organ transplantation, comprising a heterogenous group of lymphoproliferations with a spectrum of morphologic, phenotypic and molecular features. Although PTLDs are usually Epstein-Barr virus-driven B-cell lymphoproliferations, T/natural killer-cell lymphoproliferations, multiple myeloma, and Hodgkin's lymphoma are also recognized as part of the PTLD spectrum. Hairy cell leukemia, a low-grade B-cell lymphoproliferation, has not been recognized as part of the PTLD spectrum. We report the first case of hairy cell leukemia occurring after cardiac transplantation. It is unclear whether this case, similar to other cases of low-grade B-cell lymphoproliferations reported after transplantation, is related to immunosuppression and therefore part of the spectrum of PTLDs, or merely represents coincidental event occurring in an immunocompromised patient.

Characterizing CD43 expression in haematogones using multicolor flow cytometric analysis.

Haematogones are precursor B cells commonly detected in small numbers in the bone marrow. Morphologically, haematogones can mimic lymphoblasts and are best distinguished using multicolour flow cytometry with antibody combinations. Haematogones show characteristic and reproducible patterns of antigen expression representing the B-cell maturation sequence. CD43 expression, widely seen in haematopoietic elements, has not been well characterized in haematogones. We demonstrate that CD43 is consistently expressed in haematogones in a reproducible pattern similar to that of CD10 when combined with CD20. We propose that in combination with other markers, CD43 can be useful in the identification of haematogones.

T-cell post-transplantation lymphoproliferative disorders after cardiac transplantation: a single institutional experience.

Post-transplantation lymphoproliferative disorders (PTLDs) are a well-recognized and potentially life-threatening complication of solid organ transplantation. While the vast majority of PTLDs are B-cell lymphoproliferations, T-cell PTLDs are rarely seen. Among 898 patients receiving cardiac transplants between 1990 and 2003, 34 patients (3.8%) developed PTLDs with two (0.2%) T-cell PTLDs, 31 (3.5%) B-cell PTLDs and one (0.1%) natural killer cell PTLD. An additional three cases of T-cell PTLD were identified among all cardiac transplant patients followed at our institution. These T-cell PTLDs comprised a heterogeneous group of Epstein-Barr virus negative lymphoproliferations that developed late after transplantation and followed an aggressive course.

Mature B-cell acute lymphoblastic leukemia with t(9;11) translocation: a distinct subset of B-cell acute lymphoblastic leukemia.

Mature B-cell acute lymphoblastic leukemia (ALL) is typically associated with the FAB-L3 morphology and rearrangement of the MYC gene, features characteristic of the leukemic phase of Burkitt's lymphoma. However, the term 'mature' has also been used to describe other rare cases of B-ALL with light-chain surface immunoglobulin expression. In contrast, infantile B-cell ALL is generally characterized by rearrangement of the MLL gene, an immature pro-B-cell phenotype, and CD10 negativity. We describe two unusual cases of infantile B-ALL with non-L3 morphology, expressing a mature B-cell phenotype (lambda sIg+, CD19+, CD10-, TdT-, and CD34-), and showing MLL rearrangement without MYC rearrangement at presentation. Both infants relapsed after months of morphologic and genetic remission. At relapse, the t(9;11) translocation was detected in both cases by spectral karyotyping. After the initial relapse, both cases followed a rapid and aggressive course. Literature search identified few similar cases, all expressed lambda surface immunoglobulin and showed MLL rearrangement (majority with the t(9;11) translocation). These cases show that B-ALL with MLL rearrangement, especially the t(9;11) translocation, can express a 'mature' B-cell phenotype and may represent a distinct subset. Identification of additional cases will further clarify the significance of MLL rearrangements in mature B-ALL.

EBV-associated, extranodal NK-cell lymphoma, nasal type of the breast, after heart transplantation.

Post-transplantation lymphoproliferative disorders (PTLDs) are predominantly Epstein-Barr virus (EBV)-associated B-cell lymphoproliferations. PTLDs of T-cell lineage are rare, mostly reported after renal transplantation and show less frequent association with EBV. NK-cell lymphomas after transplantation (NK-cell PTLDs) are very rare; only five cases are reported so far in the English literature, all developed after renal transplantation. We describe a case of EBV-associated, extranodal NK-cell lymphoma of nasal type, involving the breast in a cardiac allograft recipient 5 years after transplantation. The neoplastic cells are positive for CD2, cytoplasmic CD3, CD7, CD43, CD56, TIA-1 and p53; and negative for surface CD3 and CD57. Analysis of T-cell receptor beta and gamma genes fails to show clonal rearrangement. EBV studies show clonal episomal integration of EBV and latency II pattern (EBER-1+, LMP-1+, EBNA-1+, EBNA-2-). In conclusion, NK-cell PTLDs are rare complications that arise relatively late after solid organ transplantation, show strong association with EBV, and can follow an aggressive clinical course. To the best of our knowledge, we present the first reported case of NK-cell PTLD after cardiac transplantation and the unifying clinical and diagnostic features of NK-cell PTLDs occurring after solid organ transplantation.