The Pax5 gene encodes the B-cell-specific activator protein which is a key regulator in development and differentiation of B-cell. We studied the expression of Pax5 in hematologic malignancies to evaluate the diagnostic utility as a B cell marker. Materials included 70 B cell lymphomas, 26 T cell lymphomas, 53 acute leukemias, and 6 multiple myelomas (MMs). Representative areas from the paraffinembedded tissues were selected for tissue microarray, and the expressions of Pax5 was immunohistochemically evaluated. Pax5 was strongly expressed in most of the B cell lymphomas; 44 of 47 diffuse large B cell lymphomas (93.6%), 15 of 16 marginal zone B cell lymphomas (93.8%), all 3 mantle cell lymphomas, 2 follicular lymphomas, and 2 Burkitt's lymphomas (100%). However, Pax5 was expressed in only one of 26 T cell lymphomas. Among leukemias, it was expressed in 10 of the 14 B acute lymphocytic leukemias (ALLs) (72.4%), but also in 3 of the 6 T ALLs (50%), 13 of the 26 acute myelogenous leukemias (AMLs) (50%) and in all 3 ALL arising in chronic myelogenous leukemias and 4 mixed B ALL and AML. In MMs, Pax5 was negative in all cases. We concluded that Pax5 is very useful B cell marker in classification of lymphomas, but not of acute leukemias.
B-Lymphocytes/pathology/physiology ; DNA-Binding Proteins/genetics/*metabolism ; Human ; Leukemia/classification/*metabolism/pathology ; Lymphoma, Non-Hodgkin/classification/*metabolism/pathology ; Support, Non-U.S. Gov't ; Tonsil/cytology/metabolism/pathology ; Transcription Factors/genetics/*metabolism ; Tumor Markers, Biological/*metabolism

Burkitt Lymphoma ; metabolism ; pathology ; Cell Nucleus ; metabolism ; Gene Expression Regulation, Neoplastic ; Humans ; Leukemia, Lymphocytic, Chronic, B-Cell ; metabolism ; pathology ; Lymphoma, B-Cell ; classification ; metabolism ; pathology ; Lymphoma, Follicular ; metabolism ; pathology ; Lymphoma, Large B-Cell, Diffuse ; metabolism ; pathology ; Lymphoma, Mantle-Cell ; metabolism ; pathology ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; metabolism ; pathology ; SOXC Transcription Factors ; genetics ; metabolism

OBJECTIVETo study the clinical and pathologic features of 4 cases of the so-called blastic natural killer (NK)-cell lymphoma, with reference to the 2008 WHO classification of tumours of haematopoietic and lymphoid tissues.

METHODSThe clinical, pathologic and immunohistochemical findings (EliVision method) of 4 cases of blastic NK-cell lymphoma (previously diagnosed according to the 2001 WHO classification) were retrospectively analyzed and reclassified with a special reference to the 2008 WHO classification.

RESULTSThe 4 cases of hematologic malignancy studied were characterized by the presence of medium-sized blastic lymphoma cells, CD56 expression, and absence of lineage-specific B-cell, T-cell and myeloid cell markers. According to the 2001 WHO classification, they fell into the category of blastic NK-cell lymphoma. Three of the cases presented with primary cutaneous lesions and expression of CD56, CD4 and CD123. They are likely derived from the plasmacytoid dendritic cells rather than NK cells. They were then, according to the 2008 WHO classification, reclassified as the blastic plasmacytoid dendritic cell neoplasm. The remaining case showed lymph node involvement, positive for CD56 and CD4, negative for CD123, and not accompanied with the cutaneous lesions. This case was provisionally classified as a ambiguous lineage leukemia-NK cell lymphoblastic leukemia/lymphoma.

CONCLUSIONSThe so-called blastic NK-cell lymphomas in the 2001 WHO classification are rare and represent a heterogeneous group of lymphoproliferative disorders, with different clinical, pathologic and immunohistochemical features. It's suggested to have a precise category when applying the 2008 WHO classification to this kind of lesion.

Adult ; Aged ; Antigens, CD ; metabolism ; Antigens, Differentiation, Myelomonocytic ; metabolism ; CD56 Antigen ; metabolism ; Humans ; Interleukin-3 Receptor alpha Subunit ; metabolism ; Killer Cells, Natural ; pathology ; Middle Aged ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; classification ; metabolism ; pathology ; Retrospective Studies ; Skin Neoplasms ; classification ; metabolism ; pathology ; World Health Organization ; Young Adult

Diagnosis, Differential ; Female ; Humans ; Immunohistochemistry ; In Situ Hybridization, Fluorescence ; Leukemia, Myeloid, Chronic-Phase ; genetics ; Lymphoma ; classification ; diagnosis ; pathology ; Male ; Neoplasms ; genetics ; metabolism ; pathology ; Oncogene Proteins ; metabolism ; Prognosis ; Prostatic Neoplasms ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Translocation, Genetic ; Tumor Suppressor Proteins ; metabolism

OBJECTIVETo identify the immunohistochemical patterns of follicular dendritic cell (FDC) meshwork and Ki-67 labeling index in small B-cell lymphomas (SBLs) and their significance in differential diagnosis.

METHODSSixty-eight cases of SBLs were included collected from November 2008 to June 2012. The patterns of FDCs and Ki-67 expression were studied on paraffin sections by CD21, CD23 and Ki-67 immunohistochemistry. The characteristic staining patterns of FDCs and Ki-67 expression among different SBLs were analyzed statistically.

RESULTSThe age of SBL patients ranged from 28 to 85 years with a mean of 55.2 years. The male to female ratio was 1.2:1. Fifty-five cases involved only lymph nodes (80.9%), and the remaining cases involved multiple extra-nodal sites. Histological classification of the cases was made according to the 2008 WHO lymphoma classification criteria: 22 were low-grade follicular lymphomas (FLs, including grade 1 and grade 2), 19 marginal zone lymphomas (MZLs), 17 mantle cell lymphomas (MCLs), and 10 chronic lymphocytic leukemia/small lymphocytic lymphomas (CLL/SLLs). FDC meshwork limited to the central part of neoplastic follicles was characteristic for FL (90.9%, 20/22). The germinal center FDC meshwork was destroyed primarily at periphery in MZL (14/19). The absence or scattered FDC clusters were typical of SLL/ CLL. Irregular FDC was seen in 7/17 of MCL, while 7/17 MCL displayed FDC pattern similar to that of CLL/SLLs. The pattern of FDCs was a significantly diagnostic feature in distinguishing the four types of SBLs (P < 0.01). Ki-67 was also a statistically significant parameter (P < 0.05) with decreasing labeling index as the following: MCL, FL, SLL and MZL. Ki-67 showed scattered pattern in germinal centers with loss of polarity in FLs. MZL presented uniformly scattered positive pattern in interfollicullar areas. Ki-67 staining was uniform in MCL, but its labeling index varied from 5% to 90%. The Ki-67 index was higher in the morphological "proliferation centers" of all CLL/SLLs.

CONCLUSIONImmunohistochemical staining patterns of FDC meshworks and Ki-67 labeling index offer a significant discriminatory power in the differential diagnoses among SBLs.

Adult ; Aged ; Aged, 80 and over ; Antigens, CD20 ; metabolism ; Dendritic Cells, Follicular ; pathology ; Diagnosis, Differential ; Female ; Humans ; Immunohistochemistry ; Ki-67 Antigen ; metabolism ; Leukemia, Lymphocytic, Chronic, B-Cell ; metabolism ; pathology ; Lymphoma, B-Cell ; classification ; metabolism ; pathology ; Lymphoma, B-Cell, Marginal Zone ; metabolism ; pathology ; Lymphoma, Follicular ; metabolism ; pathology ; Lymphoma, Mantle-Cell ; metabolism ; pathology ; Lymphoma, Non-Hodgkin ; metabolism ; pathology ; Male ; Middle Aged ; Receptors, Complement 3d ; metabolism ; Receptors, IgE ; metabolism ; Retrospective Studies

BACKGROUND: Despite the diagnostic utility of immunophenotyping for myelodysplastic syndromes (MDS), it has not been widely performed, and reports on this are absent in Korea. We aimed to evaluate the immunophenotypic features of non-blastic granulocytes, monocytes, and blasts in patients with MDS and non-clonal disorders using routine flow cytometry (FCM). Moreover, we evaluated the phenotypic abnormalities of mature cells in leukemic patients. METHODS: Marrow aspirates from 60 patients, including 18 with MDS, 18 with leukemia, and 24 with non-clonal disorders (control group), were analyzed using FCM. Blasts, non-blast myeloid cells, and monocytes were gated based on CD45 expression and side scatter (SSC). The phenotypes were then compared among the 3 groups. RESULTS: Compared to non-clonal disorders, the granulocytic lineages of MDS showed decreased SSC (P=0.005), increased CD45 intensity (P=0.020), decreased CD10-positive granulocytes (P= 0.030), and a higher CD56-positive rate (P=0.005). It is noteworthy that similar results were obtained in the leukemia group, and these findings were not related to the phenotypes of the leukemic cells. Using blast and monocytic gating, useful parameters for generating a differential diagnosis were not found. CONCLUSIONS: Gating the granulocytic region is a relatively easy method for MDS immunophenotyping. Among the parameters studied, SSC, CD10, and CD56 were the most useful for differentiating MDS from non-clonal disorders. While immunophenotypic changes in MDS appear to be useful for differentiating MDS from non-clonal disorders, these changes were also noted in the mature cells of leukemic patients.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Antigens, CD45/metabolism ; Antigens, CD56/metabolism ; Bone Marrow Cells/cytology ; Cell Lineage ; Child ; Child, Preschool ; Diagnosis, Differential ; Female ; Flow Cytometry ; Granulocytes/*classification ; Humans ; *Immunophenotyping ; Leukemia/diagnosis/pathology ; Male ; Middle Aged ; Monocytes/*classification ; Myelodysplastic Syndromes/*diagnosis ; Neprilysin/metabolism ; Phenotype