Agata M. Bogusz

Plasmablastic lymphomas with MYC/IgH rearrangement: Report of three cases and review of the literature

We report detailed clinicopathologic features of 3 cases of plasmablastic lymphoma (PBL) with MYC/IgH rearrangement, representing one third of PBL cases diagnosed at our institution. This study brings the total number of reported cases in the literature to 6. All patients were HIV+ with very low CD4 counts at diagnosis. The involved locations were mediastinum, anus, and bone marrow. Tumors exhibited predominantly immunoblastic/plasmablastic morphologic features and had a plasma cell-like immunophenotype. Bright CD38 expression by flow cytometry had a tendency to be more common in these cases compared with PBL without MYC rearrangement. All cases were positive for Epstein-Barr virus-encoded RNA but lacked human herpesvirus-8 latent nuclear antigen. The 2 patients with follow-up died within 3 months. These findings show that PBL is often associated with MYC/IgH rearrangements and that this finding may portend an aggressive clinical course, suggesting that cytogenetic studies should be routinely applied in cases of PBL.

A novel N‐terminal hydrophobic motif mediates constitutive degradation of serum‐ and glucocorticoid‐induced kinase‐1 by the ubiquitin–proteasome pathway

Serum‐ and glucocorticoid‐induced protein kinase‐1 (SGK‐1) plays a critical role in regulation of the epithelial sodium channel, ENaC. SGK‐1 also shares significant catalytic domain homology with protein kinase B (PKB/AKT‐1) and is a downstream effector of antiapoptotic phosphoinositide 3‐kinase signaling. Steady‐state levels of an active SGK‐1 are tightly regulated by rapid transcriptional activation and post‐translational modification including phosphorylation. We show here that endogenous SGK‐1 protein is polyubiquitinated and rapidly degraded by the 26S proteasome. In contrast to other rapidly degraded kinases, neither the catalytic activity of SGK‐1 nor activation site phosphorylation was required for its ubiquitin modification and degradation. Instead, SGK‐1 degradation required a lysine‐less six‐amino‐acid (amino acids 19–24) hydrophobic motif (GMVAIL) within the N‐terminal domain. Deletion of amino acids 19–24 significantly increased the half‐life of SGK1 and prevented its ubiquitin modification. Interestingly, this minimal region was also required for the association of SGK‐1 with the endoplasmic reticulum. Ubiquitin modification and degradation of SGK‐1 were increasingly inhibited by the progressive mutation of six N‐terminal lysine residues surrounding the GMVAIL motif. Mutation of all six lysines to arginine did not disrupt the subcellular localization of SGK‐1 despite a significant decrease in ubiquitination, implying that this modification per se was not required for targeting to the endoplasmic reticulum. These results suggest that constitutive ubiquitin‐mediated degradation of SGK‐1 is an important mechanism regulating its biological activity.

Quantitative Immunofluorescence Reveals the Signature of Active B Cell Receptor Signaling in Diffuse Large B Cell Lymphoma

PURPOSE B-cell receptor (BCR)-mediated signaling is important in the pathogenesis of a subset of diffuse large B-cell lymphomas (DLBCL) and the BCR-associated kinases SYK and BTK have recently emerged as potential therapeutic targets. We sought to identify a signature of activated BCR signaling in DLBCL to aid the identification of tumors that may be most likely to respond to BCR-pathway inhibition. EXPERIMENTAL DESIGN We applied quantitative immunofluorescence (qIF) using antibodies to phosphorylated forms of proximal BCR signaling kinases LYN, SYK, and BTK and antibody to BCR-associated transcription factor FOXO1 on BCR-cross-linked formalin-fixed paraffin-embedded (FFPE) DLBCL cell lines as a model system and on two clinical cohorts of FFPE DLBCL specimens (n = 154). RESULTS A robust signature of active BCR signaling was identified and validated in BCR-cross-linked DLBCL cell lines and in 71/154 (46%) of the primary DLBCL patient specimens. Further analysis of the primary biopsy samples revealed increased nuclear exclusion of FOXO1 among DLBCL with qIF evidence of active BCR signaling compared with those without (P = 0.004). Nuclear exclusion of FOXO1 was also detected in a subset of DLBCL without evidence of proximal BCR signaling suggesting that alternative mechanisms for PI3K/AKT activation may mediate FOXO1 subcellular localization in these cases. CONCLUSION This study establishes the feasibility of detecting BCR activation in primary FFPE biopsy specimens of DLBCL. It lays a foundation for future dissection of signal transduction networks in DLBCL and provides a potential platform for evaluating individual tumors in patients receiving novel therapies targeting the BCR pathway.

Massive localized lymphedema with unusual presentations: report of 2 cases and review of the literature.

Massive localized lymphedema is a benign soft tissue lesion that usually presents as a large mass in morbidly obese adults. The diagnosis may be challenging as it can mimic other lesions, including well-differentiated liposarcoma. We report 2 cases of massive localized lymphedema with unusual presentation. The first case is a recurrent massive localized lymphedema in the right thigh of a 40-year-old morbidly obese woman. In addition to typical massive localized lymphedema features such as prominent edema and vascular proliferation in the adipose tissue, we observed prominent and abundant multinucleated stromal floret-like giant cells, arborizing network of capillaries, and areas of hyalinized collagen. Our second case is in a rare location (scrotum extending into penile soft tissue) in an overweight 55-year-old male. This lesion exhibits striking smooth muscle hyperplasia. Lack of staining by antibodies against murine double minute 2 protein and cyclin dependent kinase 4 and absence of high mobility group AT- hook 2 transcription factor rearrangement by fluorescence in situ hybridization support our diagnosis of massive localized lymphedema in both cases.

Full-Length Complementary DNA and the Derived Amino Acid Sequence of Horse Uteroglobin

Abstract After its original description as a steroid-dependent protein in the rabbit uterus, uteroglobin became one of the best characterized proteins. However, detailed knowledge of its physiological role remains an enigma. In this study we investigate how its structure is phylogenetically conserved in the horse compared to other mammalian species. Northern blot analysis showed that in horses, the main expression of uteroglobin appears in lung, uterus, and prostate tissues. Western blot analysis demonstrated that the dimeric form of uteroglobin is found predominantly in biological compartments. Using a RACE-PCR technique, we cloned and sequenced the full-length cDNA (473 base pairs) that encodes equine uteroglobin. The nucleotide sequence was shown to characterize the primary structure of this protein. This enabled us to add equine uteroglobin to a comparative amino acid alignment of 8 other uteroglobin molecules, and finally, to unravel 14 evolutionary completely conserved amino acids. We summarize these results with a computer-based 3-D model of horse uteroglobin, and discuss new concepts on the physiological role of uteroglobin, in particular as a specific binding protein.

Recurrent histiocytic necrotizing lymphadenitis with a long latency in a patient with autoimmunity: a case report and review of literature.

Kikuchi–Fujimoto disease (KFD), a histiocytic necrotizing lymphadenitis (HNL), characteristically presents as cervical lymphadenopathy in young Asian women. Most resolve spontaneously with rare recurrences described. We report a patient with biopsy-proven recurrence of KFD-like HNL after almost 8 years and analyze 65 additional published cases with recurrences. While those with recurrences similarly affect young (average age = 27 years), Asian (80%) women (76%), 73% had multiple sites of involvement and 32% of those tested had underlying autoimmune conditions. Our case is unusual with respect to the following: (a) Age: 50 years, the oldest among the reported patients with recurrences. (b) Race: African descent, with only 3 others reported with recurrent HNL. Of these 4 cases, 2 had underlying autoimmunity. (c) Underlying condition: Her clinical and laboratory features were best felt to represent Sjögren’s syndrome (SjS). Only 2 other cases of SjS-associated HNL have been reported; in 2 recently reported cases SjS developed subsequently.

Diffuse large B-cell lymphoma with concurrent high MYC and BCL2 expression shows evidence of active B-cell receptor signaling by quantitative immunofluorescence.

B-cell receptor (BCR)-mediated signaling plays an important role in the pathogenesis of a subset of diffuse large B-cell lymphoma (DLBCL), and novel agents targeting this pathway are now in clinical use. We have previously identified a signature of active BCR signaling on formalin-fixed paraffin-embedded specimens using quantitative immunofluorescence, allowing for identification of patients who might benefit from anti-BCR therapies. We sought to characterize the clinicopathologic significance of active BCR signaling in DLBCL by correlating measures of signaling intensity with clinical features and various tumor cell characteristics. High MYC and concurrent high MYC and BCL2 double-expression was positively correlated with individual markers of active BCR signaling and cases with MYC/BCL2 double-expression showed overall greater BCR activation compared to cases lacking double-expression. Our findings suggest that the BCR signaling pathway may be more active in MYC/BCL2 double-expressor DLBCL and may represent a rational therapeutic target in this aggressive DLBCL subgroup.

Genetic aberrations in small B-cell lymphomas and leukemias: molecular pathology, clinical relevance and therapeutic targets

Abstract Small B-cell lymphomas and leukemias (SBCLs) are a clinically, morphologically, immunophenotypically and genetically heterogeneous group of clonal lymphoid neoplasms, including entities such as chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), mantle cell lymphoma (MCL), follicular lymphoma (FL), lymphoplasmacytic lymphoma (LPL), marginal zone lymphoma (MZL) and hairy cell leukemia (HCL). The pathogenesis of some of these lymphoid malignancies is characterized by distinct translocations, for example t(11;14) in the majority of cases of MCL and t(14;18) in most cases of FL, whereas other entities are associated with a variety of recurrent but nonspecific numeric chromosomal abnormalities, as exemplified by del(13q14), del(11q22), and +12 in CLL, and yet others such as LPL and HCL that lack recurrent or specific cytogenetic aberrations. The recent surge in next generation sequencing (NGS) technology has shed more light on the genetic landscape of SBCLs through characterization of numerous driver mutations including SF3B1 and NOTCH1 in CLL, ATM and CCND1 in MCL, KMT2D and EPHA7 in FL, MYD88 (L265P) in LPL, KLF2 and NOTCH2 in splenic MZL (SMZL) and BRAF (V600E) in HCL. The identification of distinct genetic lesions not only provides greater insight into the molecular pathogenesis of these disorders but also identifies potential valuable biomarkers for prognostic stratification, as well as specific targets for directed therapy. This review discusses the well-established and recently identified molecular lesions underlying the pathogenesis of SBCLs, highlights their clinical relevance and summarizes novel targeted therapies.

Extreme Signet Ring Cell Change in a Large B-Cell Lymphoma of Follicular Origin

We report a large B-cell lymphoma of follicular origin with extreme signet ring cell differentiation. Initially classified as follicular lymphoma on a fine needle core biopsy, the presence of cohesive sheets of extrafollicular signet ring cells triggered an excisional biopsy for further characterization. The excised lymph node revealed focal follicular hyperplasia, follicular lymphoma, and a neoplasm composed of vague nodules and sheets of large atypical cells, all of which virtually exhibited large clear intracytoplasmic vacuoles with peripheral displacement of nuclei. The tumor cells were negative for mucin and lacked immunoreactivity with pancytokeratin, but were strongly immunoreactive with CD20, BCL-2, BCL-6, and CD10 antibodies. Electron microscopy studies revealed electron-lucent vacuoles with no particular internal structure. This case is unique in that extreme signet ring cell differentiation somewhat obscured the true cytological identity of the interfollicular lymphoma and suggested alternative diagnoses.

EBV-Negative Monomorphic B-Cell Posttransplant Lymphoproliferative Disorder with Marked Morphologic Pleomorphism and Pathogenic Mutations in ASXL1, BCOR, CDKN2A, NF1, and TP53

Posttransplant lymphoproliferative disorders (PTLDs) are a diverse group of lymphoid or plasmacytic proliferations frequently driven by Epstein-Barr virus (EBV). EBV-negative PTLDs appear to represent a distinct entity. This report describes an unusual case of a 33-year-old woman that developed a monomorphic EBV-negative PTLD consistent with diffuse large B-cell lymphoma (DLBCL) 13 years after heart-lung transplant. Histological examination revealed marked pleomorphism of the malignant cells including nodular areas reminiscent of classical Hodgkin lymphoma (cHL) with abundant large, bizarre Hodgkin-like cells. By immunostaining, the malignant cells were immunoreactive for CD45, CD20, CD79a, PAX5, BCL6, MUM1, and p53 and negative for CD15, CD30, latent membrane protein 1 (LMP1), and EBV-encoded RNA (EBER). Flow cytometry demonstrated lambda light chain restricted CD5 and CD10 negative B-cells. Fluorescence in situ hybridization studies (FISH) were negative for cMYC, BCL2, and BCL6 rearrangements but showed deletion of TP53 and monosomy of chromosome 17. Next-generation sequencing studies (NGS) revealed numerous genetic alterations including 6 pathogenic mutations in ASXL1, BCOR, CDKN2A, NF1, and TP53(x2) genes and 30 variants of unknown significance (VOUS) in ABL1, ASXL1, ATM, BCOR, BCORL1, BRNIP3, CDH2, CDKN2A, DNMT3A, ETV6, EZH2, FBXW7, KIT, NF1, RUNX1, SETPB1, SF1, SMC1A, STAG2, TET2, TP53, and U2AF2.