Role of immunoglobulin heavy and light chain gene rearrangement analysis in differentiating between benign and malignant bone marrow B-cell lymphoid aggregates.

Lymphoid aggregates are found in a minority of bone marrow biopsy and aspirate specimens, and when present, the distinction between benign and malignant aggregates can represent a diagnostic challenge. Morphologic and immunophenotypic evaluation of the aggregates can aid in that distinction but in a few cases, detection of immunoglobulin heavy chain (IGH) and kappa light chain (IGK) gene rearrangements may be needed to rule in or out a malignant disease process. We studied the role of testing for IGH/IGK rearrangements in the distinction between benign and malignant B cell-predominant lymphoid aggregates. Only a few studies have addressed this issue and most lacked an adequate number of cases for establishing statistical significance. Our study retrospectively evaluated 120 bone marrow aspirate and biopsy specimens, 79 cases originally diagnosed with benign lymphoid aggregates [4,5], and 41 demonstrating a B-cell lymphoma with malignant aggregates. Immunohistochemical stains were performed on all cases in our study and flow cytometry results were available in the vast majority of cases (98%). All patients included in our study but 9 had at least 2 years of clinical follow-up information. Of the malignant lymphoma cases, IGH/IGK rearrangements were demonstrated by polymerase chain reaction in 60% of the cases. Moreover, clonal rearrangements were identified in 15% of the cases with benign aggregates. After at least 2 years of follow-up, only one case with a positive clonality study occurring in the setting of morphologically benign-appearing bone marrow lymphoid aggregates experienced a relapse of non-Hodgkin lymphoma. Molecular analysis of the IGH and IGK genes may have utility in confirming the presence of malignancy in bone marrow aspirates and biopsy specimens. False-negative results, however, are possible due to testing limitations and sampling issues. Moreover, patients with conditions such as autoimmune disorders or infectious diseases are shown to also develop clonal B-cell lymphoid aggregates. As a result, we recommend a thorough morphological examination, informative immunohistochemical staining, accurate flow cytometric analysis, and current IGH/IGK rearrangement testing when evaluating bone marrow specimens containing B cell-predominant lymphoid aggregates, with the knowledge that molecular clonality results should be carefully interpreted in the context of morphological and immunophenotypic findings to prevent misdiagnosis.

Rare case of leptomeningeal small lymphocytic lymphoma with TP53 mutation detected by deep next-generation sequencing.

Involvement of the central nervous system (CNS) is an exceedingly rare presentation of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), with no consensus on the optimal therapy. Here we describe a 71-year-old man with a skull-base leptomeningeal mass consistent with SLL on biopsy. Malignant cells were observed in the cerebrospinal fluid (CSF), but not in the peripheral blood, bone marrow, or other extramedullary sites. Molecular analysis of the patient's disease by next generation sequencing (NGS) detected no pathogenic mutations in 111 genes, with the exception of two low allele frequency variants identified during deep NGS analysis of TP53. The patient was treated with six cycles of high-dose methotrexate and systemic/intrathecal rituximab followed by venetoclax monotherapy, with complete resolution of CSF disease and radiographic decrease in size of the skull base lesion.

Infection prevention strategies are highly protective in COVID-19 units while main risks to healthcare professionals come from coworkers and the community.

BACKGROUND: Early evaluations of healthcare professional (HCP) COVID-19 risk occurred during insufficient personal protective equipment and disproportionate testing, contributing to perceptions of high patient-care related HCP risk. We evaluated HCP COVID-19 seropositivity after accounting for community factors and coworker outbreaks. METHODS: Prior to universal masking, we conducted a single-center retrospective cohort plus cross-sectional study. All HCP (1) seen by Occupational Health for COVID-like symptoms (regardless of test result) or assigned to (2) dedicated COVID-19 units, (3) units with a COVID-19 HCP outbreak, or (4) control units from 01/01/2020 to 04/15/2020 were offered serologic testing by an FDA-authorized assay plus a research assay against 67 respiratory viruses, including 11 SARS-CoV-2 antigens. Multivariable models assessed the association of demographics, job role, comorbidities, care of a COVID-19 patient, and geocoded socioeconomic status with positive serology. RESULTS: Of 654 participants, 87 (13.3%) were seropositive; among these 60.8% (N = 52) had never cared for a COVID-19 patient. Being male (OR 1.79, CI 1.05-3.04, p = 0.03), working in a unit with a HCP-outbreak unit (OR 2.21, CI 1.28-3.81, p < 0.01), living in a community with low owner-occupied housing (OR = 1.63, CI = 1.00-2.64, p = 0.05), and ethnically Latino (OR 2.10, CI 1.12-3.96, p = 0.02) were positively-associated with COVID-19 seropositivity, while working in dedicated COVID-19 units was negatively-associated (OR 0.53, CI = 0.30-0.94, p = 0.03). The research assay identified 25 additional seropositive individuals (78 [12%] vs. 53 [8%], p < 0.01). CONCLUSIONS: Prior to universal masking, HCP COVID-19 risk was dominated by workplace and community exposures while working in a dedicated COVID-19 unit was protective, suggesting that infection prevention protocols prevent patient-to-HCP transmission. Prior to universal masking, HCP COVID-19 risk was dominated by workplace and community exposures while working in a dedicated COVID-19 unit was protective, suggesting that infection prevention protocols prevent patient-to-HCP transmission.

Aggressive CD5-Positive Primary Bone Marrow Diffuse Large B-Cell Lymphoma with Leukemic Presentation.

Primary bone marrow diffuse large B-cell lymphoma is an exceedingly rare form of non-Hodgkin lymphoma. It may demonstrate a leukemic presentation, and a proportion of cases have CD5 expression. The prognostic implications of this CD5-positivity remain unknown. Here, we present a 78-year-old man who presented with circulating peripheral blood lymphoma cells and a hypercellular marrow involved by diffuse large B-cell lymphoma, germinal center B-cell subtype. The patient responded favorably to six cycles of etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab (EPOCH-R) and intrathecal methotrexate. He unfortunately relapsed in several enlarged inguinal lymph nodes and succumbed to the lymphoma approximately one year after diagnosis, demonstrating the particularly aggressive clinical course of his disease.

EBV-Associated Lymphoproliferative Disorders: Update in Classification.

Although about 90% of the world's population is infected by EBV only a small subset of the related infections result in neoplastic transformation. EBV is a versatile oncogenic agent involved in a multitude of hematopoietic, epithelial, and mesenchymal neoplasms, but the precise role of EBV in the pathogenesis of many of the associated lymphoid/histiocytic proliferations remains hypothetical or not completely understood. Additional studies and use of evolving technologies such as high-throughput next-generation sequencing may help address this knowledge gap and may lead to enhanced diagnostic assessment and the development of potential therapeutic interventions.

Crucial role for pathology residents in laboratory self-inspection, a single Institute's experience.

BACKGROUND: Training in patient safety, quality, and management is a key component of Graduate Medical Education (GME) training in all specialties. However, residency programs, especially Pathology programs, often find it challenging to create strong learning opportunities in these areas. OBJECTIVES: Focused quality assurance (QA) projects are one approach to teach and engage trainees in these key areas. Residents have been historically involved in different QA projects in our department but mainly in small secondary roles. Leading a large QA project that can enhance residents' management skills and improve clinical operations in our laboratory was the main objective of our project. DESCRIPTION: A new process for laboratory self-inspection led by residents was implemented that simulates the exact process of a formal outside College of American Pathologists (CAP) inspection. We aim to prove that resident-led QA activities not only have profound educational benefit but can also result in significant performance and operational improvement. RESULTS: For this paper, we focus on the Histology laboratory since the ramifications from the self-inspection process during a three year period were profound leading to change in management, workflow changes, and notable improvement in staff morale. CONCLUSION: The self-inspection process exposed the residents to operational issues and corrective actions that provided them the opportunity to take a more active role in laboratory management and helped prepare them for post-graduation challenges. It also helped the department identify and rectify many operational issues, confirmed by the enumeration of CAP deficiencies and significant improvement of staff morale.

Epstein-Barr virus incidental expression in bone marrow cells: a study of 230 consecutive bone marrow biopsy samples.

Epstein-Barr virus (EBV) is associated with many neoplastic hematologic conditions, but scattered EBV-positive cells can be detected in lymph nodes of healthy individuals and they usually represent latently infected lymphocytes. The incidence of EBV detection in normal bone marrow samples has not been studied and is largely unknown. The lack of knowledge regarding the true incidence of encountering bystander latent EBV-positive cells in the bone marrow may potentially lead to a diagnostic dilemma when assessing a staging bone marrow for a patient with an EBV-positive B or T/NK-cell lymphoma. The aim of our study was to investigate the rate of detection of EBV expression in bone marrow samples and correlate any positive findings with various clinical parameters including patient's age, sex, clinical history, immune status, and any neoplastic transformation if follow-up data are available. We retrospectively studied 230 consecutive bone marrow biopsies performed in 2013 and found 5 cases (2.17%) with scattered EBV-positive cells by in situ hybridization. The observed scattered EBV-positive cells are largely small in size and likely represent bystander, latently infected cells. The rate of detection of EBV-positive cells in the bone marrow appears to be slightly higher in immunodeficient individuals (3%) than in immunocompetent patients (1%).

Prolymphocytic transformation of lymphoplasmacytic lymphoma: an extremely unusual event.

Although rare cases of prolymphocytic transformation from splenic B-cell lymphomas and follicular lymphoma have been reported, prolymphocytic transformation from lymphoplasmacytic lymphoma has not been previously reported. We report a case of 76-year-old-male patient with a history of Waldenström macroglobulinemia diagnosed in 2010 and treated with infusion chemotherapy. He was in clinical remission for 5 years. In 2016, he presented with diffuse lymphadenopathy, and a head and neck lymph node biopsy showed lymphoplasmacytic lymphoma. MYD88 mutation was detected by polymerase chain reaction. A subsequent bone marrow biopsy showed B-cell lymphoma with increased prolymphocytes. Peripheral blood showed numerous circulating prolymphocytes. MYD88 was detected by polymerase chain reaction in the bone marrow. Cerebrospinal fluid was positive for lymphoma cells with prolymphocytic morphology. An IgM κ paraprotein was noted by immunofixation performed on the patient's serum, urine, and cerebrospinal fluid. The patient was resistant to chemotherapy, developed multiorgan failure, and died shortly thereafter.

Epstein - Barr virus association with plasma cell neoplasms.

AIMS: Epstein-Barr virus (EBV) expression has been reported in several hematopoietic and non-hematopoietic disorders but its expression in plasma cell neoplasms has been largely limited to immunodeficiency-related cases such as in the setting of post-organ transplantation or human immunodeficiency virus (HIV) infection. The aim of this study is to evaluate the association of EBV with plasma cell neoplasms, mainly in immunocompetent patients. METHODS AND RESULTS: We retrospectively studied 147 cases of patients with different plasma cell neoplasms (109 plasma cell myelomas, 22 plasmacytomas, and 16 monoclonal gammopathy cases). Six patients were immunocompromised. EBV was positive in 6 cases; 3 immunocompromised (2 patients with HIV infection and 1 patient was post-renal transplant) and 3 immunocompetent patients with plasmacytoma and variable plasmablastic features. CONCLUSIONS: Our data shows that EBV was negative in all plasma cell myeloma cases in immunocompetent patients and has an overall low association with the different plasma cell neoplasms in the immunocompetent setting. When expressed, it is usually associated with variable plasmablastic features.

Epstein-Barr virus (EBV)-associated lymphoid proliferations, a 2018 update.

Epstein-Barr virus (EBV) has been linked to many human neoplasms including hematopoietic, epithelial, and mesenchymal tumors. Since our original review of EBV-associated lymphoproliferative disorders in 2007, many advances and developments have been reported. In this review, we will examine the recent advances in EBV-associated lymphoid/histiocytic proliferations, dividing them into reactive, B cell, T/NK cell, immunodeficiency-related, and histiocytic/dendritic cell proliferations.

Differentiating benign from malignant bone marrow B-cell lymphoid aggregates: a statistical analysis of distinguishing features.

CONTEXT: Lymphoid aggregates are seen in a minority of bone marrow biopsy specimens, and when present, their neoplastic nature is often apparent by morphologic evaluation. However, the distinction between benign and malignant aggregates can be a diagnostic challenge when there are multiple aggregates with no documented history of lymphoma. OBJECTIVE: To aid in the distinction between benign and malignant B-cell lymphoid aggregates. DESIGN: Previously, we described specific distribution patterns for B and T lymphocytes within bone marrow aggregates. To statistically analyze the significance of these patterns as well as previously reported criteria, we examined 128 bone marrow specimens with benign aggregates and 78 specimens with documented malignant B-cell aggregates and calculated specific odds ratios (ORs) and 95% confidence intervals (CIs) to aid in differentiating between benign and malignant B-cell aggregates. RESULTS: Aggregates with infiltrative edges (OR, 80.54; 95% CI, 31.76-204.21), a B-cell pattern (OR, 30.08; 95% CI, 13.28-68.10), paratrabecular location (OR, 10.17; 95% CI, 3.96-26.12), size greater than 600 µm (OR, 6.83: 95% CI, 3.61-12.93), or cytologic atypia correlated with malignancy. CONCLUSIONS: When taken collectively, the presence of more than 2 of these characteristic features was strongly predictive of malignancy.

Thyroid-like follicular carcinoma of the kidney in a young patient with history of pediatric acute lymphoblastic leukemia.

Thyroid-like follicular carcinoma of the kidney (TLFCK) is a rare histological variant of renal cell carcinoma not currently included in the World Health Organization classification of renal tumors. Only 24 previous cases of TLFCK have been reported to date. We report a case of TLFCK in a 19-year-old woman with history of pediatric acute lymphoblastic leukemia. This patient is the youngest with TLFCK to be reported to date and the first with history of lymphoblastic leukemia. The development of TLFCK in a young patient with history of lymphoblastic leukemia is interesting and suggests that genes involved in leukemogenesis may also be important for TLFCK pathogenesis. Recognition of TLFCK is important to distinguish it from other conditions that show thyroid-like features, as a misdiagnosis can result in adverse patient care.

Human herpesvirus 8-unrelated primary effusion lymphoma-like lymphoma: report of a rare case and review of 54 cases in the literature.

OBJECTIVES: To report a patient with primary effusion lymphoma who was negative for human herpesvirus-8 (HHV-8), human immunodeficiency virus, Epstein-Barr virus, hepatitis C virus, and hepatitis B virus, as well as review 54 reported cases of HHV-8-unrelated primary effusion lymphoma (PEL)-like lymphoma in the literature to clarify the nature of this entity. METHODS: The patients' characteristics, clinical presentation, pathogenesis, morphologic-immunophenotypic features, clinical management, and prognosis were studied. RESULTS: HHV-8-negative PEL-like lymphomas often occur in immunocompetent and elderly patients, are sometimes associated with chronic inflammation-related fluid overload, are mostly large B-cell or large B-cell with plasmacytic differentiation type, and are associated with a better prognosis. CONCLUSIONS: In various aspects, HHV-8-unrelated PEL-like lymphoma is a different entity from HHV-8-related PEL. Immunophenotype, morphology, and c-myc/8q24 status should be included for differential diagnosis. A test for c-myc or 8q24 abnormalities should be recommended for subdividing HHV-8-unrelated PEL-like lymphoma, which may have benefits in patient management.

Follicular dendritic cells: origin, function, and different disease-associated patterns.

Follicular dendritic cells (FDCs) are a specialized type of antigen-presenting dendritic cells that are largely restricted to lymphoid follicles. They form dense three-dimensional meshwork patterns within benign follicles, which maintain the follicular architecture. The FDC function is to bind and retain antigens by linking to complement and immune complexes and then present these antigens to germinal center B cells that start the secondary immune response. FDCs aid in the rescue of bound B cells from apoptosis, and induce the differentiation of B cells into long-term memory B cell clones or plasma cells. We will discuss the different patterns of the FDC meshwork observed in different types of reactive and neoplastic disorders, which may be due to underlying different roles that FDCs may play in these disorders and whether changes in the architecture of the FDC meshwork can be useful in routine diagnostic practice or have a prognostic value.

Benign lymphoid aggregates in the bone marrow: distribution patterns of B and T lymphocytes.

Benign lymphoid aggregates are seen in only a minority of bone marrow specimens, but their distinction from non-Hodgkin lymphoma, particularly B-cell lymphomas, can represent a diagnostic challenge. Although criteria have been proposed to help distinguish between benign and malignant aggregates, a detailed description of the distribution patterns of B and T lymphocytes within benign lymphoid aggregates has not been investigated. One hundred thirty-seven cases of bone marrow specimens containing benign aggregates were studied with a panel of immunostains. A subset of these cases was also examined for immunoglobulin gene rearrangements by polymerase chain reaction. The aggregates were categorized based on size, location (paratrabecular or random), presence of infiltrating edges, and distribution of lymphoid cell populations. In addition, we examined 40 cases of bone marrow biopsies with documented malignant lymphoid aggregates for comparison purposes. We report that the distribution of B and T lymphocytes within lymphoid aggregates may serve as a useful criterion to aid in the separation between benign and malignant aggregates. When aggregates exhibit a predominance of T cells, consist of a central core of T cells surrounded by a rim of B cells, or have a mixed distribution of B and T cells, they are more likely to be benign. On the other hand, an increased likelihood of malignancy occurs when aggregates exhibit a predominance of B cells or consist of a central core of B cells surrounded by a rim of T cells (excluding germinal center formation), and assessing other features worrisome of malignancy (large aggregate size, presence of infiltrative edges, cellular atypia, and paratrabecular location, among others) is warranted.

Extraosseous plasmacytoma with an aggressive course occurring solely in the CNS.

Extraosseous (extramedullary) plasmacytoma is a relatively indolent neoplasm that constitutes 3-5% of all plasma cell neoplasms. Rare cases have been reported to truly occur in the CNS and not as an extension from a nasal lesion. EBV expression in plasma cell neoplasms has been reported in very few cases that are mainly post-transplant or occurring in severely immunosuppressed patients. We report a case of extraosseous plasmacytoma with an aggressive course in an HIV-positive individual that occurred solely in the CNS, showing EBV expression by in situ hybridization, and presenting as an intraparenchymal mass as well as in the CSF.

Solitary plasmacytoma of the bone involving young individuals, is there a role for preceding trauma?

Solitary plasmacytoma of the bone (SPB) is a rare plasma cell neoplasm that usually presents as a lytic lesion mainly localized within the axial skeleton. The occurrence of SPB in young individuals is exceedingly rare but has been sporadically reported before. We report a case of SPB involving a 21 year-old male with a prior history of trauma at the same site. We also reviewed all previous cases of SPB in young individuals that were accessible to us to investigate the incidence of prior trauma in such cases and to investigate a potential role that trauma may play in the pathogenesis of such lesions.

Do indeterminate cells follow the footsteps of Langerhans cells and migrate from the skin to the lymph node?

Indeterminate cells are considered by many to be pre-Langerhans cells as they mimic Langerhans cells in certain morphologic and immunophenotypic aspects. Indeterminate cells express CD1a and S-100 but lack Langerin expression (Langerin is used as an immunohistochemical substitute for electron microscopy for the detection of Birbeck granules). Migration of Langerhans cells to the lymph nodes through the dermal lymphatics to present skin antigens to T lymphocytes has been well defined before; however, the migration and the identification of indeterminate cells in lymph node has not been investigated before. In our study, we attempt to investigate the presence of indeterminate cells in normal lymph nodes and in lymph nodes with dermatopathic lymphadenitis and analyze their possible coexistence with Langerhans cells. We examined 9 cases of normal skin, 7 cases of normal lymph nodes (both normal skin and normal lymph nodes are obtained from mastectomy specimens), and 5 cases of reactive lymph nodes with dermatopathic lymphadenitis, for the presence of indeterminate cells. A set panel of immunostains was used that included CD1a, S-100, Langerin, CD3, and CD20. Indeterminate cells were defined as CD1a+, S-100+, and Langerin-, whereas Langerhans cells were defined as CD1a+, S-100+, and Langerin+. Scattered indeterminate cells were identified in most lymph nodes with dermatopathic lymphadenitis, but only in those normal lymph nodes that showed paracortical hyperplasia or expansion, whereas Langerhans cells were identified in both.

Extranodal NK/T-cell lymphoma, nasal type extensively involving the bone marrow.

Extranodal NK/T-cell lymphoma, nasal type, is an aggressive EBV-associated lymphoma that mainly involves the nasal cavity but has also been reported to involve other extranodal sites without nasal involvement. In contrast to aggressive NK cell leukemia (a marrow-based aggressive leukemia of NK-cell origin); extensive bone marrow and blood involvement is extremely uncommon by nasal type NK/T lymphoma. We report a patient with extranodal NK/T-cell lymphoma, nasal type that developed extensive bone marrow involvement during the course of her disease with some overlapping features with aggressive NK-cell leukemia.

Indeterminate cell tumor: a rare dendritic neoplasm.

Indeterminate cell tumor (ICT) is a rare neoplastic dendritic cell disorder that has been poorly defined due to its rarity and poorly understood histogenesis and pathogenesis. It is characterized by a proliferation of dendritic cells, which mimic Langerhans cells immunophenotypically (positive for CD1a and S-100 protein), but lack Birbeck granules characteristic of Langerhans cells. The clinical, morphologic, immunophenotypic, and ultrastructural features of 5 ICT cases are reported in an attempt to further define ICT and to examine the postulated relationship between indeterminate cells and Langerhans cells. Four of 5 patients were females, and 4 of 5 were older than 68 years. Three of 5 patients had cutaneous lesions, whereas 2 presented with cervical lymph node involvement. Two patients had a possible association with lymphoma: first patient had a history of progressive follicular lymphoma that led to patient's demise and the second patient had unexplained systemic lymphadenopathy and died 1 week after the biopsy. All 5 ICT cases expressed CD1a and S-100 protein, but lacked Langerin expression and Birbeck granules ultrastructurally. Interestingly, a t(14;18) was detected by fluorescence in situ hybridization in the ICT cells of the patient with previous follicular lymphoma and a monoclonal kappa light chain gene rearrangement was detected by polymerase chain reaction in the patient with systemic lymphadenopathy. In both cases, there was no morphologic or immunophenotypic evidence of a concurrent B-cell lymphoma. In conclusion, ICT is a rare neoplasm that can occur de novo or in association with a B-cell lymphoma, possibly as a result of B-cell dedifferentiation caused by relatively unknown mechanisms. Finally, Langerin immunostaining may be used as a surrogate marker for the ultrastructural demonstration of Birbeck granules, the absence of which represents a strong diagnostic criterion for ICT.