Zenggang Pan

Expression of PKC-beta or cyclin D2 predicts for inferior survival in diffuse large B-cell lymphoma

We sought to determine whether identification of poor-risk subgroups of diffuse large B-cell lymphoma (DLBCL) using immunohistochemical stains would have practical utility with regard to prognosis and therapeutic decisions. Tissue microarray blocks were created using replicate samples of formalin-fixed, paraffin-embedded tissue from 200 cases of de novo DLBCL. The sections were stained with antibodies to proteins that are expressed by activated or proliferating B cells including MUM1, FOXP1, bcl-2, survivin, protein kinase C-beta (PKC-β), cyclin D2, cyclin D3, and Ki-67. In univariate analysis, tumor expression of cyclin D2 (P=0.025) or PKC-β (P=0.015) was associated with a worse overall survival, whereas none of the other markers was predictive of overall survival. Patients with DLBCL that expressed either cyclin D2 or PKC-β had a 5-year overall survival of only 30% as compared to 52% for those who were negative for both markers (P=0.0019). In multivariate analysis, the expression of cyclin D2 or PKC-β was an independent predictor of poor overall survival (P=0.035). Cyclin D2 and PKC-β expression will be useful in designing a ‘biological prognostic index’ for patients with DLBCL.

Two Newly Characterized Germinal Center B-Cell-Associated Genes, GCET1 and GCET2, Have Differential Expression in Normal and Neoplastic B Cells

A group of genes are highly expressed in normal germinal center (GC) B cells and GC B-cell-derived malignancies based on cDNA microarray analysis. Two new genes, GCET1 (germinal center B-cell expressed transcript 1) and GCET2, were cloned from selected expressed sequence tags (IMAGE clone 1334260 and 814622, respectively). GCET1 is located on chromosome 14q32 and has four splicing isoforms, of which the longest one is 1787 bp and encodes a 435-amino acid protein. GCET2 is located on 3q13.13, and the cloned fragment is 3270 bp, which encodes a protein of 178 amino acids. Blast search showed that GCET1 has a highly conserved serine proteinase inhibitor (SERPIN) domain and is located on a chromosomal locus containing seven other SERPIN family members. GCET2 is a likely homologue of the mouse gene M17, a GC-expressed transcript. Analysis of the GCET2 protein sequence indicated that it may be involved in signal transduction in the cytoplasm. Northern blot and real-time polymerase chain reaction analyses confirmed that GCET1 is highly restricted to normal GC B cells and GCB-cell-derived cell lines. Although GCET2 is also a useful marker for normal and neoplastic GC B cells, it has a wider range of expression including immature B and T cells. Real-time polymerase chain reaction assay showed that both GCET1 and GCET2 are preferentially expressed in follicular lymphoma and diffuse large B-cell lymphoma with GC B-cell differentiation, confirming previous microarray gene expression analysis, but neither one is entirely specific. Multiple markers are necessary to differentiate the GCB from the activated B-cell type of diffuse large B-cell lymphoma with a high degree of accuracy.

ALK-positive large b-cell lymphoma

Anaplastic lymphoma kinase–positive large B-cell lymphoma (ALK+ LBCL) is a rare, aggressive subtype of diffuse large B-cell lymphoma with characteristic ALK rearrangements. Diagnosis of ALK+ LBCL can be challenging because of its rarity, unique morphologic characteristics, and unusual immunophenotypic features, which significantly overlap with other hematologic and nonhematologic neoplasms. The purpose of this study is to further explore the clinicopathologic features of ALK+ LBCL to ensure the awareness and accurate diagnosis of this entity. We retrospectively reviewed the data from 26 cases in our institutions and additional 108 cases from the literature. ALK+ LBCL typically occurred in the lymph nodes of young and middle-aged, immunocompetent patients. The medium age was 35 years with a male to female ratio of 3.5:1. Vast majority of cases showed immunoblastic and/or plasmablastic morphology. All cases expressed ALK protein with a cytoplasmic granular pattern in most of them. Common B-cell markers (CD20, CD79a, and PAX5) were typically negative, but the tumor cells mostly expressed 2 B-cell transcriptional factors, BOB1 and OCT2. The 5-year overall survival (OS) was 34%, and the median survival was 1.83 years. In patients with stage III/IV disease, the 5-year OS was only 8%. Moreover, patients below 35 years of age had a significantly better OS than those aged 35 years or above.

Primary Langerhans cell histiocytosis of the vulva: Report of a case and brief review of the literature

Primary Langerhans cell histiocytosis (LCH) of the vulva is rare. Fifteen cases of primary cutaneous vulvar LCH have been reported in English literature. We report an additional case of LCH confined to the vulva. In this article, we describe the clinical presentation, histopathology and immunohistochemistry findings of vulvar LCH that are helpful to both gynecologists and pathologists in the diagnosis of this entity. We briefly discuss the pathogenesis of LCH. The debate whether LCH is a reactive or neoplastic entity is still ongoing.

Studies of a germinal centre B-cell expressed gene, GCET2, suggest its role as a membrane associated adapter protein

GCET2 (Germinal centre B‐cell expressed transcript 2; also named HGAL) is a newly cloned gene that has been shown to be a useful marker for germinal centre (GC) B cells and GC B‐cell derived malignancies, including follicular lymphomas and germinal centre B cell‐like diffuse large B‐cell lymphomas (GCB‐DLBCLs), and is a useful prognosticator for DLBCLs. We report here the biochemical and biological properties of GCET2, which may help to determine its role in the GC reaction. GCET2 is constitutively localised in the plasma membrane but is excluded from lipid rafts. GCET2 does not have a transmembrane domain, and its membrane localisation is mediated by myristoylation and palmitoylation. GCET2 has five conserved putative tyrosine phosphorylation sites, and it can be phosphorylated following pervanadate treatment in B cells. By serially mutating the five tyrosines, the third and fourth tyrosines were found to be essential for GCET2 phosphorylation. GCET2 was phosphorylated when co‐transfected into COS7 cells with protein tyrosine kinases (PTKs) LYN, LCK or SYK, and therefore it could be a substrate of these kinases in B cells. The third tyrosine site (107YENV) of GCET2 is a consensus GRB2 binding site, and GCET2 was found to associate with GRB2 through the third tyrosine following phosphorylation. Our data suggests that GCET2 may be an adaptor protein in GC B cells that transduces signals from GC B‐cell membrane to the cytosol via its association with GRB2.

Significant Variation of Immunohistochemical Marker Expression in Paired Primary and Metastatic Clear Cell Renal Cell Carcinomas

OBJECTIVES To compare the immunohistochemical expression of diagnostic markers in primary clear cell renal cell carcinomas (RCCs) and their matched metastases. METHODS Tissue microarrays were constructed from 15 pairs of primary and metastatic clear cell RCCs and then evaluated for the immunohistochemical expression of renal cell carcinoma antigen (RCCA), kidney-specific cadherin, carbonic anhydrase IX (CAIX), and paired box genes 2 (PAX2) and 8 (PAX8). RESULTS There was significantly higher overall marker expression in metastatic tumors compared to their matched primaries (P < .001). Individually, there was greater CAIX, PAX2, and PAX8 expression and lower RCCA expression in metastatic tumors. Most importantly, a significant proportion of originally RCCA-positive tumors lost such expression in metastases. CONCLUSIONS Metastatic RCCs have significantly higher expression of PAX2 and PAX8 compared to primary RCCs. RCCA is not very reliable in this diagnostic setting, both because of its lower overall sensitivity and loss of expression in metastatic RCCs.

Merkel cell carcinoma of lymph node with unknown primary has a significantly lower association with Merkel cell polyomavirus than its cutaneous counterpart

Rare cases of Merkel cell carcinoma have been encountered in lymph nodes with unknown extranodal primary, which exhibit similar morphologic and immunophenotypic features to those in primary cutaneous Merkel cell carcinomas. However, it is uncertain whether the nodal Merkel cell carcinoma is a primary tumor of the lymph node or represents a metastasis from an occult or regressed extranodal lesion. To establish an accurate diagnosis of the nodal Merkel cell carcinoma can be challenging because of significant morphologic mimics, including lymphoblastic lymphoma and metastatic small cell carcinoma. Moreover, there is no consensus for a diagnostic term, and many different terms have been used, which can be confusing and may not fully reflect the nature of nodal Merkel cell carcinoma. In this study, we investigated the detailed clinicopathologic features of 22 nodal Merkel cell carcinomas, with comparison to 763 primary cutaneous cases retrieved from the literature. Overall, the nodal and cutaneous Merkel cell carcinomas shared similar clinical presentations, morphologic spectrum, and immunophenotype; both were mostly seen in elderly male with a typical neuroendocrine morphology. Most of cases expressed CK20, synaptophysin, and chromogranin A; and PAX5 and TdT were also positive in majority of cases. However, nodal Merkel cell carcinomas had a significantly lower association with Merkel cell polyomavirus than cutaneous cases (31% vs 76%, P=0.001). Therefore, these two entities may arise from overlapping but not identical biological pathways. We also recommend the use of the diagnostic term ‘Merkel cell carcinoma of lymph node’ to replace many other names used.

PD-1 Blockade in Mediastinal Gray-Zone Lymphoma

Mediastinal gray-zone lymphoma is intermediate between classic Hodgkin’s lymphoma and primary mediastinal B-cell lymphoma. Three patients whose disease had become refractory to chemotherapy had impressive responses to PD-1 blockade.

Extranodal NK/T Cell Lymphoma, Nasal Type (ENKTL-NT): An Update on Epidemiology, Clinical Presentation, and Natural History in North American and European Cases

Purpose of ReviewExtranodal NK/T cell lymphoma, nasal type (ENKTL-NT) is an aggressive extranodal non-Hodgkin lymphoma most commonly occurring in East Asia and Latin America but with increasing incidence in the United States. Data on epidemiology, disease presentation, and outcome for European and North American (“Western”) cases are very limited. We review published landmark clinical studies on ENKTL-NT in the West and report in detail recent data, including our institutional experience.Recent FindingsWe highlight key observations in its epidemiology, natural history, and trends in clinical management. In the USA, ENKTL-NT is more common among Asian Pacific Islanders (API) and Hispanics compared to non-Hispanic whites. Published studies indicate less heterogeneity in clinical presentation in Western ENKTL-NT compared to Asian patients. While there is variation in age at diagnosis, presence of antecedent lymphoproliferative disorders, and outcomes among racial/ethnic groups, the universal association of ENKTL-NT with EBV and the poor response of this neoplasm to anthracycline-based therapy is consistent across all geographic areas.SummaryData on epidemiology, disease presentation, and clinical outcomes in mature T cell and NK cell (T/NK cell) neoplasms, including ENKTL-NT, in Europe and North America are very limited. As the classification and diagnostic characterization of the currently recognized T/NK cell lymphoma disease entities continue to evolve, gaps and inconsistencies in data reporting across different studies are being recognized. Despite these limitations, several studies from the USA suggest that the incidence of ENKTL-NT is higher in Asian Pacific Islanders (API) and non-white Hispanics and that outcomes may be worse in non-whites. However, the universal association of ENKTL-NT with Epstein-Barr virus (EBV) across all ethnic groups suggests a common pathogenesis. Given the overlap between the entities included in the category of T/NK cell neoplasms, there is a need to further define biological and clinical differences that may affect diagnosis, treatment, and outcome.

Fine needle aspiration cytology of histiocytic sarcoma with dendritic cell differentiation: A case of transdifferentiation from low-grade follicular lymphoma

Histiocytic sarcoma (HS) is a rare malignant tumor, and in extraordinary circumstances it can be transdifferentiated from a low‐grade B‐cell lymphoma. In our report, a 62‐year‐old female was initially diagnosed with a low‐grade follicular lymphoma, and 2 years later she presented with bilateral lung masses and lymphadenopathy. Fine needle aspiration (FNA) of the lung masses revealed solid nests of large pleomorphic epithelioid cells. By immunohistochemical studies, the tumor cells were positive for histiocytic markers (CD68 and CD163) and S100, supporting a diagnosis of HS with dendritic cell differentiation. Further fluorescence in situ hybridization (FISH) analyses detected IGH@/BCL2 rearrangement in both the previous follicular lymphoma and the current HS, which was highly suggestive of the clonal relationship between these two tumors. To the best of our knowledge, this is the first case of transformation of follicular lymphoma into HS diagnosed by FNA of lung masses. Diagn. Cytopathol. 2015;43:659–663.