Kedar V. Inamdar

A novel recurrent NPM1-TYK2 gene fusion in cutaneous CD30-positive lymphoproliferative disorders

The spectrum of cutaneous CD30-positive lymphoproliferative disorders (LPDs) includes lymphomatoid papulosis and primary cutaneous anaplastic large cell lymphoma. Chromosomal translocations targeting tyrosine kinases in CD30-positive LPDs have not been described. Using whole-transcriptome sequencing, we identified a chimeric fusion involving NPM1 (5q35) and TYK2 (19p13) that encodes an NPM1-TYK2 protein containing the oligomerization domain of NPM1 and an intact catalytic domain in TYK2. Fluorescence in situ hybridization revealed NPM1-TYK2 fusions in 2 of 47 (4%) primary cases of CD30-positive LPDs and was absent in other mature T-cell neoplasms (n = 151). Functionally, NPM1-TYK2 induced constitutive TYK2, signal transducer and activator of transcription 1 (STAT1), STAT3, and STAT5 activation. Conversely, a kinase-defective NPM1-TYK2 mutant abrogated STAT1/3/5 signaling. Finally, short hairpin RNA-mediated silencing of TYK2 abrogated lymphoma cell growth. This is the first report of recurrent translocations involving TYK2, and it highlights the novel therapeutic opportunities in the treatment of CD30-positive LPDs with TYK2 translocations.

The Value of CD23 Expression as an Additional Marker in Distinguishing Mediastinal (Thymic) Large B-Cell Lymphoma From Hodgkin Lymphoma

Mediastinal diffuse large B-cell lymphoma (Med-DLBCL) is a subtype of DLBCL that has morphologic and clinical similarities and phenotypic overlaps with classical Hodgkin lymphoma (CHL) involving the mediastinum. CD23 is a marker that has been previously reported in Med-DLBCI and is proposed in the differential diagnosis of M-DLBCL and CHL. A panel of immunostains, including CD45, CD20, CD3, CD30, CD15, CD21, and CD23 as well as Eber was performed on Med-DLBCL and 20CHL. 23/27 Med-DLBCL (85%) were positive for CD23 (membranous) CD30 was negative in 6 and positive in 21 cases. 18 CHL cases were negative for CD23 and only 2 showed rare scattered Reed—Sternberg cells with weak cytoplasmic CD23 staining. CD23 showed a sensitivity of 85% and positive predictive value of 92%. In conclusion CD23 is a useful marker in distinguishing Med-DLBCL and CHL in mediastinal biopsies and may be helpful as an adjunct to histomorphology and other markers in the diagnosis and appropriate clinical management of these lesions.

Differential expression of aurora-A kinase in T-cell lymphomas

Aurora-A is a mitotic kinase implicated in oncogenesis and is known to be overexpressed in B-cell lymphomas and plasma cell myeloma. The expression of Aurora-A kinase (henceforth referred to as Aurora-A) in T-cell lymphomas is not well characterized. In this study, we assessed Aurora-A expression by immunohistochemical analysis in 100 lymphomas encompassing a variety of T-cell lymphomas as categorized in the World Health Organization classification. Aurora-A expression was highest in anaplastic large-cell lymphomas and variably expressed in other types of T-cell lymphomas. In addition, the pattern of Aurora-A expression was predominantly cytoplasmic in ALK-positive anaplastic large-cell lymphoma and was nuclear in ALK-negative anaplastic large-cell lymphoma and other T-cell lymphomas, suggesting altered biochemical mechanisms of Aurora-A nuclear transport in ALK-positive anaplastic large-cell lymphoma. Reverse transcriptase-PCR analysis showed that Aurora-A is more highly expressed in ALK-positive anaplastic large-cell lymphoma than in ALK-negative anaplastic large-cell lymphoma, and is relatively lower in peripheral T-cell lymphomas. Using western blot analysis and the DEL cell line (derived from ALK-positive anaplastic large-cell lymphoma), we showed that Aurora-A expression is decreased after treatment with either MYC or MEK inhibitors, consistent with the MYC and MAP kinase signaling pathways being involved in driving Aurora-A expression; the greatest decrease was observed after MYC inhibition. These findings provide insights into the possible importance of Aurora-A overexpression in anaplastic large-cell lymphoma pathogenesis, and also suggest that Aurora-A inhibition could be a potential therapeutic approach for patients with anaplastic large-cell lymphoma.

Blastic plasmacytoid dendritic cell neoplasm

Sixty-six-year-old female presented with left forearm soft tissue swelling for 2 months. An ultrasound of her left forearm showed a 6.5 cm 3 1 cm 3 3.6 cm soft tissue mass, which was also confirmed by magnetic resonance imaging (Panel A and B). A routine screening mammogram revealed a new 4 mm mass in her left breast. Subsequent left breast needle biopsy and left forearm fine needle aspiration favored an undifferentiated malignant neoplasm of hematolymphoid origin (Panel D) with positive CD4 (Panel E) and positive CD56 (Panel F) markers compatible with blastic plasmacytoid dendritic cell neoplasm (BPDCN). Positron emission tomography (PET) scan showed increased uptake in the left forearm (Panel C), left breast, bilateral pleura, liver, spleen, portocaval lymph nodes, and omental caking. A bone marrow biopsy was negative for malignancy, and shortly thereafter the patient underwent induction therapy with cytarabine and idarubicin. Following progression of metastatic disease on PET scan, the patient received reinduction chemotherapy with mitoxantrone, etoposide, and cytarabine. BPDCN is a rare malignancy formerly recognized as CD41/CD561 hematodermic neoplasm and is suggested to have derived from plasmacytoid dendritic cells. It typically presents in middle-aged or elderly patients with skin or soft tissue involvement and concurrent disseminating disease carrying poor prognosis. BPDCN expresses CD4, CD56, CD123 (interleukin-3 receptor alpha chain), and BDCA-2 (blood dendritic cell antigen 2), whereas expression of TCL1 is helpful when the tissue displays weak expression of aforementioned markers. Treatment involves multiagent chemotherapy followed by subsequent stem cell transplantation for best outcomes. Unfortunately, our patient showed dismal response to chemotherapy, and the originally intended stem cell transplantation could not be instituted due to poor performance status.

Cystic tumor of the atrioventricular node: an unexpected finding in an explanted heart

SUMMARY We report herein a unique case of cystic tumor of atrioventricular (AV) node (CTAVN), which, to our knowledge, is the first of its kind diagnosed in an explanted heart specimen and only the fourth diagnosed antemortem. Often, this rare tumor can only be diagnosed by careful gross examination and adequate sampling of AV node region. It is an important differential diagnosis in young patients with syncopal attacks and varying degrees of heart blocks. CONTEXT CTAVN is a rare, benign tumor. Most cases have been reported in young females (mean age, 38 years). Patients typically present with conduction abnormalities including complete heart block leading to sudden cardiac death. Most cases have been identified at autopsy; no cases to our knowledge have been reported in an explanted heart. DESIGN A 19 year-old female presented to the cardiac transplant clinic for evaluation of severe congestive heart failure felt to be secondary to postpartum cardiomyopathy. The patients history was significant for congenital heart block requiring placement of a permanent pacemaker at 12 years of age. At the time of this presentation, electrocardiogram revealed second-degree AV block, and two-dimensional echocardiogram showed lipomatous hypertrophy of the interatrial septum. Seven months later, orthotopic cardiac transplantation was performed. RESULTS On gross examination, the explanted heart weighed 500 g and had biventricular dilatation. Histologic sections of left and right ventricle revealed myocyte hypertrophy and interstitial fibrosis consistent with dilated cardiomyopathy. Sections from the AV node showed a lesion with morphological features of CTAVN. It was composed of cysts of varying sizes lined by transitional, cuboidal and squamous epithelium. Some cysts were filled with proteinaceous debris that were periodic acid Schiff-positive and diastase resistant. CONCLUSIONS CTAVN occurs exclusively in the area of the AV node, tricuspid valve, and inferior atrial septum. These lesions are now believed to be endodermal in origin, although mesothelial origin was earlier proposed. We report herein a case of CTAVN, the first of its kind diagnosed in an explanted heart specimen and only the fourth diagnosed antemortem.

Peripheral T-cell lymphomas of follicular helper T-cell type frequently display an aberrant CD3 −/dim CD4 + population by flow cytometry: an important clue to the diagnosis of a Hodgkin lymphoma mimic

Nodal follicular helper T-cell-derived lymphoproliferations (specifically the less common peripheral T-cell lymphomas of follicular type) exhibit a spectrum of histologic features that may mimic reactive hyperplasia or Hodgkin lymphoma. Even though angioimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma of follicular type share a common biologic origin from follicular helper T-cells and their morphology has been well characterized, flow cytometry of peripheral T-cell lymphomas of follicular type has not been widely discussed as a tool for identifying this reactive hyperplasia/Hodgkin lymphoma mimic. We identified 10 peripheral T-cell lymphomas of follicular type with available flow cytometry data from five different institutions, including two cases with peripheral blood evaluation. For comparison, we examined flow cytometry data for 8 classical Hodgkin lymphomas (including 1 lymphocyte-rich classical Hodgkin lymphoma), 15 nodular lymphocyte predominant Hodgkin lymphomas, 15 angioimmunoblastic T-cell lymphomas, and 26 reactive nodes. Lymph node histology and flow cytometry data were reviewed, specifically for the presence of a CD3−/dimCD4+ aberrant T-cell population (described in angioimmunoblastic T-cell lymphomas), besides other T-cell aberrancies. Nine of 10 (90%) peripheral T-cell lymphomas of follicular type showed a CD3−/dimCD4+ T-cell population constituting 29.3% (range 7.9–62%) of all lymphocytes. Five of 10 (50%) had nodular lymphocyte predominant Hodgkin lymphoma or lymphocyte-rich classical Hodgkin lymphoma-like morphology with scattered Hodgkin-like cells that expressed CD20, CD30, CD15, and MUM1. Three cases had a nodular growth pattern and three others exhibited a perifollicular growth pattern without Hodgkin-like cells. Epstein–Barr virus was positive in 1 of 10 cases (10%). PCR analysis showed clonal T-cell receptor gamma gene rearrangement in all 10 peripheral T-cell lymphomas of follicular type. By flow cytometry, 11 of 15 (73.3%) angioimmunoblastic T-cell lymphomas showed the CD3−/dimCD4+ population (mean: 19.5%, range: 3–71.8%). Using a threshold of 3% for CD3−/dimCD4+ T cells, all 15 nodular lymphocyte predominant Hodgkin lymphoma controls and 8 classical Hodgkin lymphomas were negative (Mann–Whitney P=0.01, F-PTCL vs Hodgkin lymphomas), as were 25 of 26 reactive lymph nodes. The high frequency of CD3−/dimCD4+ aberrant T cells is similar in angioimmunoblastic T-cell lymphomas and peripheral T-cell lymphomas of follicular type, and is a useful feature in distinguishing peripheral T-cell lymphomas of follicular type from morphologic mimics such as reactive hyperplasia or Hodgkin lymphoma.

Post-transplant CD4+ non-cytotoxic γδ T cell lymphoma with lymph node involvement

Gamma delta T cells represent a minor subset of the normal lymphocyte component of the human immune system, largely inhabiting mucosal surfaces. Gamma delta T cell lymphomas (γδ TCLs) are thought to be derived from these cells and are rare, extremely aggressive lymphomas that typically exhibit a cytotoxic phenotype and often present in extranodal sites, most commonly as cutaneous or hepatosplenic subtypes. The immunophenotype usually lacks both CD4 and CD8 expression, but occasional cases express CD8. CD4 expression in γδ TCLs is exceedingly rare. The few reported cases tend to show a non-cytotoxic phenotype with preferential involvement of the lymph nodes. Cases showing cutaneous presentation or with an immunosuppressive clinical history, while relatively common among typical γδ TCLs, are even rarer among this unusual CD4+ subset. While this very small group appears to have an equally dismal prognosis to other types of γδ TCL, little else is known as to how they may differ biologically and whether they should be treated as a separate entity. We report a unique case of CD4-positive gamma delta T cell lymphoma with skin and systemic lymph node involvement in the post-transplant setting.

Trends in Bone Marrow Sampling and Core Biopsy Specimen Adequacy in the United States and CanadaA Multicenter Study

Objectives To assess bone marrow (BM) sampling in academic medical centers. Methods Data from 6,374 BM samples obtained in 32 centers in 2001 and 2011, including core length (CL), were analyzed. Results BM included a biopsy (BMB; 93%) specimen, aspirate (BMA; 92%) specimen, or both (83%). The median (SD) CL was 12 (8.5) mm, and evaluable marrow was 9 (7.6) mm. Tissue contraction due to processing was 15%. BMB specimens were longer in adults younger than 60 years, men, and bilateral, staging, and baseline samples. Only 4% of BMB and 2% of BMB/BMA samples were deemed inadequate for diagnosis. BM for plasma cell dyscrasias, nonphysician operators, and ancillary studies usage increased, while bilateral sampling decreased over the decade. BM-related quality assurance programs are infrequent. Conclusions CL is shorter than recommended and varies with patient age and sex, clinical circumstances, and center experience. While pathologists render diagnoses on most cases irrespective of CL, BMB yield improvement is desirable.

Polo-like-kinase 1 (PLK-1) and c-myc inhibition with the dual kinase-bromodomain inhibitor volasertib in aggressive lymphomas

Survival following anthracycline-based chemotherapy remains poor among patients with most T-cell lymphoproliferative disorders. This may be attributed, at least in part, to cell-autonomous mechanisms of chemotherapy resistance observed in these lymphomas, including the loss of important tumor suppressors and the activation of signaling cascades that culminate in the expression and activation of transcription factors promoting cell growth and survival. Therefore, the identification of novel therapeutic targets is needed. In an effort to identify novel tumor dependencies, we performed a loss-of-function screen targeting ≈500 kinases and identified polo-like kinase 1 (PLK-1). This kinase has been implicated in the molecular cross-talk with important oncogenes, including c-Myc, which is itself an attractive therapeutic target in subsets of T-cell lymphomas and in high-grade (“double hit”) diffuse large B-cell lymphomas. We demonstrate that PLK-1 expression is prevalent among these aggressive lymphomas and associated with c-myc expression. Importantly, PLK-1 inhibtion with the PLK-1 inhibitor volasertib significantly reduced downstream c-myc phosphorylation and impaired BRD4 binding to the c-myc gene, thus inhibiting c-myc transcription. Therefore, volasertib led to a nearly complete loss of c-myc expression in cell lines and tumor xenografts, induced apoptosis, and thus warrants further investigation in these aggressive lymphomas.

Plasma cell myeloma mimicking classical Hodgkin lymphoma in the bone marrow

further evaluation, and revealed focal areas with bizarre anaplastic cells (Fig. 1), many of which resembled Reed Sternberg cells. There was also some granulomatous inflammation in the background. By immunohistochemistry, these A 49-year-old woman presented with anemia, thrombocytopenia and back pain. Imaging revealed multiple paraspinal soft tissue masses as well as a destructive bone lesion in the pelvis. This bone marrow biopsy was performed for