Laboratory Features and Pathology of Cytokine Storm Syndromes.

The laboratory diagnosis of cytokine storm syndromes (CSSs), i.e., hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS), is often challenging. The laboratory features using routinely available tests lack specificity, whereas confirmatory testing is available in only few laboratories in the United States. The disease mechanisms are still largely unclear, particularly in adults. In this chapter, the pathogenesis of CSSs, their associated laboratory findings, and recommended diagnostic strategies are reviewed.

B-Cell Acute Lymphoblastic Leukemia with iAMP21 in a Patient with Constitutional Ring Chromosome 21.

Pediatric B-cell acute lymphoblastic leukemia (B-ALL) is associated with various specific cytogenetic and molecular markers that significantly influence treatment and prognosis. Intrachromosomal amplification of chromosome 21 (iAMP21) defines a rare distinct cytogenetic subgroup of childhood B-ALL, which is characterized by amplification of region 21q22.12 comprising the RUNX1 gene. Constitutional structural chromosomal abnormalities involving chromosome 21 confer an increased risk for B-ALL with iAMP21. Here, we report the development of B-ALL with iAMP21 in a 9-year-old child with a constitutional ring chromosome 21, r(21)c, uncovered after B-ALL diagnosis. Cytogenetic and microarray analysis of the post-therapy sample revealed an abnormal chromosome 21 lacking a satellite and having a deletion of the terminal 22q22.3 region, consistent with a constitutional ring chromosome 21, r(21)(p11.2q22). On a retrospective analysis, this ring chromosome was observed in the normal cells in the pre-treatment diagnostic specimen. Constitutional ring chromosome 21 may remain undetected in patients with mild or no neurodevelopmental phenotype, posing an unknown lifelong risk of developing B-ALL with iAMP21. Individuals with constitutional structural chromosome 21 rearrangements such as ring 21 require a close surveillance and long-term follow-up studies to establish their risk of B-ALL relapse and possibility of developing other malignancies. Germline analysis is recommended to all pediatric patients with iAMP21-related B-ALL to rule out structural chromosome 21 rearrangements and to elucidate molecular mechanisms of iAMP21 formation.

Conjunctival Lymphoma With Nasal Spread Through the Nasolacrimal Duct.

Conjunctival mucosa-associated lymphoid tissue lymphoma classically presents as a subconjunctival mass, most often in the fornix. The presence of conjunctival mucosa-associated lymphoid tissue lymphoma with spread down the nasolacrimal duct has only been reported once previously. The authors present a case of a 35-year-old woman with a right conjunctival mass in the inferior fornix along with sinus congestion and fullness. A biopsy of the conjunctival mass and the nasal turbinate revealed a conjunctival mucosa-associated lymphoid tissue lymphoma. Therefore, it is important to consider spread down the nasolacrimal duct in patients with conjunctival lymphoma also presenting with difficulty breathing or nasal congestion.

Human herpesvirus 8-related diseases: Histopathologic diagnosis and disease mechanisms.

The emergence of HIV/AIDS more than three decades ago led to an increased incidence of diseases caused by HHV8 co-infection, particularly Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman disease. Over time, the development of highly effective AIDS therapies has resulted in a decreased incidence of HHV8-associated entities, which are now more commonly found in patients with undiagnosed and/or untreated AIDS. Due to their rarity, some of these diseases may be difficult to recognize without appropriate clinical information. This article provides an overview of HHV8-related disorders, with a focus on their morphologic and phenotypic features, and includes a brief overview of laboratory methods used to detect HHV8. Disease mechanisms by which the HHV8 virion promotes tumorigenesis are also reviewed.

Immunophenotypic features by multiparameter flow cytometry can help distinguish low grade B-cell lymphomas with plasmacytic differentiation from plasma cell proliferative disorders with an unrelated clonal B-cell process.

Highly sensitive flow cytometry studies may incidentally identify B cell clones when used to assess plasma cell clonality in bone marrows. Clinical history, which can help differentiate related clones (low grade B cell lymphoma with plasmacytic differentiation/LBCL-PD) from unrelated ones (plasma cell proliferative disorder (PCPD) with an unrelated B cell clone), is often unavailable in referred specimens. We sought to identify morphologic or phenotypic features that would help predict the significance of these clones in the absence of history. We included only cases with identical light chain B and plasma cell clones, as determined by 6-color flow cytometry with additional DNA ploidy analysis, in which the relationship between clones could be established by review of medical records. There were 26 cases; 18 were related (14 were Waldenstrom macroglobulinemia) and eight were unrelated (seven multiple myeloma). Features seen exclusively in LBCL-PD include CD19+/CD45+ clonal plasma cell phenotype (66·7%, P = 0·0022) and morphologic features such as paratrabecular bone marrow involvement, increased mast cells, and plasma cells surrounding B-cell nodules. Aneuploidy was identified exclusively in PCPD cases (75%, P = 0·000028). We conclude that CD19+/CD45+ clonal plasma cell phenotype and aneuploidy are useful in distinguishing related clones (LBCL-PD) from unrelated clones (PCPD).

Bone marrow findings of the newly described TEMPI syndrome: when erythrocytosis and plasma cell dyscrasia coexist.

TEMPI syndrome (telangiectasias, elevated erythropoietin level and erythrocytosis, monoclonal gammopathy, perinephric fluid collections, and intrapulmonary shunting) is a recently described syndrome that, owing to erythrocytosis, may be confused with polycythemia vera. It is best classified as a type of plasma cell dyscrasia with paraneoplastic manifestations, similar to POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin abnormalities). To date, 11 patients have been identified. This is the first morphologic review of TEMPI syndrome bone marrow samples, in order to define pathologic features that may aid in the recognition of the syndrome and to identify post-therapy changes. Seven bone marrow aspirates and biopsies from three patients, including two post-treatment marrows, were examined. Patients were 36, 49, and 49 years old at time of diagnosis. In all cases, erythropoietin levels were extremely elevated at >5000 IU/l, the paraprotein was IgG kappa, JAK2 V617F was negative and vascular endothelial growth factor levels were normal. In one case, the increase in clonal plasma cells reached levels of smoldering myeloma (18%), but remaining marrows showed few monoclonal plasma cells (<5%). All pre-treatment biopsies showed erythroid hyperplasia, with mild nonspecific megakaryocytic, and erythroid cytologic atypia in one marrow. Prominent plasma cell vacuolization and reactive-appearing lymphoid aggregates were noted in one case. Findings of myeloproliferative neoplasms, including megakaryocyte clusters and fibrosis, were not identified. In conclusion, TEMPI syndrome should be considered when erythrocytosis and plasma cell dyscrasia coexist. The bone marrow findings, although nonspecific, differ significantly from polycythemia vera. Peculiar clinical and laboratorial findings of TEMPI, including elevated erythropoietin and normal vascular endothelial growth factor level, allow the diagnosis and distinction from POEMS syndrome. Significant decrease in erythropoietin level following treatment suggests a role of erythropoietin in monitoring therapeutic response.

Fibrin-Associated Large B-Cell Lymphoma (FA-LBCL) Involving Solid Organs as Necrotic Cystic Lesions-A Rare Entity with Potential Diagnostic Pitfalls: A Two-Case Series and Review of the Literature.

Fibrin-associated large B-cell lymphoma (FA-LBCL) is a rare subtype of Epstein-Barr virus (EBV)-associated lymphoma, recognized as an independent entity per the 5th edition of the WHO classification of hematolymphoid neoplasms. It is usually associated with longstanding chronic inflammation and arises within fibrinous material in confined anatomic spaces. We report the clinicopathologic manifestations of two patients of FA-LBCL involving the adrenal gland and kidney. Both tumors were diagnosed after presenting as cystic masses on imaging studies. These lymphomas were non-invasive, with microscopic aggregates of large B-lymphoma cells along/within cystic wall and admixed with fibrinous material and without prominent inflammation. By immunohistochemistry and in-situ hybridization, lymphoma cells were positive for CD45, PAX5, CD79a, MUM1, BCL2, PD-L1, and EBV/EBER (Epstein-Barr virus encoded small RNA) with a high proliferation index. Both patients remain in remission after management with complete surgical resection and additional chemo-immunotherapy in one patient. Considering its rarity, scant tumor cells, and varied clinical presentations, FA-LBCL may pose diagnostic challenges, especially when presenting as extensively necrotic cystic lesions, needing multidisciplinary collaboration in formulating management.

Clinicopathologic features of relapsed CD19(-) B-ALL in CD19-targeted immunotherapy: Biological insights into relapse and LILRB1 as a novel B-cell marker for CD19(-) B lymphoblasts.

INTRODUCTION: The mechanism of relapsed CD19(-) B-ALL after anti-CD19 immunotherapy (Kymriah [CART-19] and blinatumomab) is under active investigation. Our study aims to assess LILRB1 as a novel B-cell marker for detecting CD19(-) B-lymphoblasts and to analyze the clinicopathologic/genetic features of such disease to provide biological insight into relapse. METHODS: Six patients (3 males/3 females, median age of 14 years) with relapsed CD19(-) B-ALL were analyzed for cytogenetic/genetic profile and immunophenotype. RESULTS: CD19(-) B-ALL emerged after an interval of 5.8 months following anti-CD19 therapy. Five of six patients had B-cell aplasia, indicative of a persistent effect of CART or blinatumomab at relapse. Importantly, LILRB1 was variably expressed on CD19(-) and CD19(+) B lymphoblasts, strong on CD34(+) lymphoblasts and dim/partial on CD34(-) lymphoblasts. Three of six patients with paired B-ALL samples (pre- and post-anti-CD19 therapy) carried complex and different cytogenetic abnormalities, either as completely different or sharing a subset of cytogenetic abnormalities. CONCLUSION: LILRB1 can be used as a novel B-cell marker to identify CD19(-) B lymphoblasts. The emergence of CD19(-) B-ALL appears to be associated with complex cytogenetic evolutions. The mechanism of CD19(-) B-ALL relapse under anti-CD19 immune pressure remains to be explored by comprehensive molecular studies.

Comprehensive Next-Generation Sequencing Testing in a Patient with TEMPI Syndrome.

TEMPI syndrome is a new and poorly understood disease that is currently considered a type of plasma cell neoplasm with paraneoplastic manifestations. The TEMPI acronym defines the hallmarks of the syndrome: T for telangiectasia; E for erythrocytosis with elevated erythropoietin; M, monoclonal gammopathy; P, perinephric collections; and I, intrapulmonary shunting. Due to the marked erythrocytosis as the most common presenting feature, TEMPI is often misdiagnosed as polycythemia vera. However, unlike polycythemia vera, TEMPI is not associated with a JAK2 mutation. The pathogenesis of TEMPI syndrome is unknown, although a few hypothetical disease mechanisms have been previously discussed. Here we present a new case of TEMPI syndrome, discuss results of a next-generation sequencing (NGS) panel covering 1,425 known cancer-related genes, and review the current literature with focus on an update of the genetics of TEMPI syndrome. This is the first report of TEMPI that includes results of comprehensive NGS testing.

PCNEO, a New Proficiency Testing Program for Flow Cytometric Analysis of Plasma Cell Neoplasms From the College of American Pathologists Diagnostic Immunology and Flow Cytometry Committee.

CONTEXT.­: In 2018 the College of American Pathologists Diagnostic Immunology and Flow Cytometry Committee designed and implemented a new plasma cell neoplasia flow cytometry proficiency testing program-PCNEO-to allow clinical flow cytometry laboratories to monitor and assess their performance compared with a peer group. OBJECTIVE.­: To report the results from the first 4 years of the PCNEO program. DESIGN.­: Program participants were sent 2 sets of challenges per year, each including 1 wet challenge and 2 dry challenges, with associated clinical and laboratory findings. The wet challenges were composed of myeloma cell line specimens (with or without dilution in preserved whole blood) for flow cytometric analysis. The dry (paper) challenges were composed of clinical case summaries and images of flow cytometric test results from various flow cytometry laboratories of committee members. RESULTS.­: A total of 116 to 145 laboratories from 17 countries enrolled in the proficiency testing program. For the wet challenges, almost all participants (97%-100%; cumulative, 98.2%) correctly identified the presence of neoplastic plasma cell populations based on flow cytometric analysis of undiluted myeloma cell lines. Slightly fewer participants (89.0%-97.4%; cumulative, 95.2%) correctly identified the presence of neoplastic plasma cell populations based on flow cytometric analysis of diluted myeloma cell lines (10% or 50% dilutions into peripheral blood) intended to better represent a typical clinical sample. There was generally agreement among 80% or more of participants for positive or negative staining for CD38, CD138, CD19, CD20, and surface and cytoplasmic κ and λ light chains. Similarly, 84% to 100% of participants were able to correctly identify the presence of neoplastic plasma cell populations in paper challenges, including the presence of small, neoplastic plasma cell populations (0.01%-5.0% clonal plasma cells), or the presence of nonneoplastic plasma cell populations (correctly identified by 91%-96% of participants). CONCLUSIONS.­: Participant performance in the new proficiency testing program was excellent overall, with the vast majority of participants able to perform flow cytometric analysis and identify neoplastic plasma cell populations, and to identify small plasma cell clones or expanded populations of reactive plasma cells in dry challenge flow cytometry results. This program will allow laboratories to verify the accuracy of their testing program and test interpretations for the assessment of patients suspected of having a plasma cell neoplasm.

A Combined Biomarker of Bright CD38 and MYC ≥55% Is Highly Predictive of Double-/Triple-Hit High-Grade B-Cell Lymphoma.

OBJECTIVES: Diagnosis of high-grade B-cell lymphoma with MYC and BCL2 or BCL6 rearrangements (double-/triple-hit lymphoma [DTHL]) appears to mandate fluorescence in situ hybridization (FISH) testing for all large B-cell lymphoma (LBCL). Given the low incidence of DTHL, we aimed to identify flow cytometry (FC) and immunohistochemistry (IHC) features of DTHL that could be used to develop an optimal screening strategy. This combined FC-IHC approach has not yet been studied. METHODS: We compared features of 40 cases of DTHL and 39 cases of diffuse LBCL (DLBCL) without MYC rearrangement. RESULTS: Bright CD38 expression (CD38bright) by FC, high MYC expression (≥55%), and double-expressor phenotype by IHC were significantly associated with DTHL. The biomarker combining FC and IHC, CD38bright and/or MYC ≥55%, was superior to FC and IHC markers alone in predicting DTHL. Restricting FISH testing to approximately 25% of LBCL based on CD38brightand/or MYC ≥55% would detect approximately 95% of DTHL-BCL2 and approximately 75% of DHL-BCL6. CONCLUSIONS: Our study demonstrated that the novel biomarker of CD38bright and/or MYC ≥55% is highly predictive of DTHL. Awareness of the advantages and limitations of this screening strategy would facilitate development of a rational diagnostic workflow to provide high-quality patient care.

Reactive Lymphadenopathies.

Lymphadenitis in the pediatric population frequently is benign and self-limited, often caused by infections. In children with refractory symptoms, lymph node biopsy may be indicated to rule out malignancy or obtain material for culture. Acute bacterial infections typically show a suppurative pattern of necrosis with abscess formation. Viral infections are associated with nonspecific follicular and/or paracortical hyperplasia. Granulomatous inflammation is associated with bacterial, mycobacterial, and fungal infections. Toxoplasma lymphadenitis displays follicular hyperplasia, monocytoid B-cell hyperplasia, and clusters of epithelioid histiocytes. Autoimmune and noninfectious inflammatory disorders are included in differential diagnosis of lymphadenitis. Infectious mononucleosis and Kikuchi-Fujimoto lymphadenitis may mimic Hodgkin and non-Hodgkin lymphomas.

PD1/PD-L1 Expressions in Plasmablastic Lymphoma with Clinicopathological Correlation.

The activation of the programmed cell death one (PD1)/PD1 ligand (PD-L1) immune checkpoint pathway is a mechanism of immune evasion characterized by the upregulation of PD-L1 expression by tumor cells and by the tumor microenvironment. This activation leads to the inhibition of PD1-positive T cells and to a decrease in the anti-tumor immune response. Plasmablastic lymphoma (PBL) is an aggressive type of large B-cell lymphoma with limited studies on the frequency of PD1 and PD-L1 expressions and their clinical impact. As PBL is associated with immune suppression in immunocompromised individuals, we hypothesize that the PD1/PD-L1 axis may be relevant in this type of lymphoma. Our study demonstrates a subset of PBL cases with a higher PD-L1 expression by tumor cells [nPD-L1high, in 4 of 21 (19%) cases] and by tumor microenvironment [macrophages/stromal cells, sPD-L1high, in 9 of 21 (43%) cases]. While nPD-L1 expression showed no significant correlation with PD1 expression on tumor-infiltrating lymphocytes, or other clinicopathological parameters, it positively correlated with sPD-L1 expression. Moreover, patients with nPD-L1high had a tendency towards a shorter overall survival (median 9.3 vs. 25.5 months in nPD-L1low patients). In conclusion, our study provides a rationale to identify, by immunohistochemistry, a subset of nPD-L1high patients who may benefit from clinical trials of PD1/PD-L1 checkpoint blockade. Further studies on large cohorts are needed to investigate prognostic and predictive biomarkers for the PD1/PD-L1 pathway in PBL patients.

Primary peripheral T-cell central nervous system lymphoma.

BACKGROUND: Primary peripheral T-cell central nervous system lymphoma (PCNSL) is a rare, aggressive tumor that arises in the craniospinal axis and has an increased risk in individuals who are immunocompromised. This lesion often mimics other benign and malignant processes on radiographic imaging, leading to misdiagnosis and delays in treatment. We present a case of a patient with a history of Sjögren's syndrome and progressive neurologic symptoms who underwent craniotomy for diagnosis. CASE DESCRIPTION: A 61-year-old woman with a history of Sjögren's syndrome, progressive aphasia, left facial droop, and right-sided paresthesias for 4 months presented for evaluation and management. An enhancing, infiltrative lesion in the left frontal lobe with underlying vasogenic edema was appreciated and suggestive of a primary or metastatic neoplasm. The patient underwent an open biopsy for further evaluation of the lesion. Extensive histopathologic evaluation revealed a diagnosis of T-cell PCNSL. The patient was started on induction methotrexate and temozolomide followed by consolidative radiotherapy. CONCLUSION: Autoimmune conditions are a risk factor for T-cell PCNSL development. T-cell PCNSL has radiographic and gross histologic features that are consistent with a broad differential, including gliomas and inflammatory processes. Prompt diagnosis and extensive histopathological evaluation is essential to ensure appropriate treatment.

Participation in the College of American Pathologists Laboratory Accreditation Program Decreases Variability in B-Lymphoblastic Leukemia and Plasma Cell Myeloma Flow Cytometric Minimal Residual Disease Testing: A Follow-up Survey.

CONTEXT.­: Minimal residual disease (MRD) testing by flow cytometry is ubiquitous in hematolymphoid neoplasm monitoring, especially B-lymphoblastic leukemia (B-ALL), for which it provides predictive information and guides management. Major heterogeneity was identified in 2014. Subsequently, new Flow Cytometry Checklist items required documentation of the sensitivity determination method and required lower level of detection (LLOD) inclusion in final reports. This study assesses Laboratory Accreditation Program (LAP) participation and new checklist items' impact on flow cytometry MRD testing. OBJECTIVES.­: To survey flow cytometry laboratories about MRD testing for B-ALL and plasma cell myeloma. In particular, enumerate the laboratories performing MRD testing, the proportion performing assays with very low LLODs, and implementation of new checklist items. DESIGN.­: Supplemental questions were distributed in the 2017-A mailing to 548 flow cytometry laboratories subscribed to the College of American Pathologists FL3 Proficiency Testing Survey (Flow Cytometry-Immunophenotypic Characterization of Leukemia/Lymphoma). RESULTS.­: The percentage of laboratories performing MRD studies has significantly decreased since 2014. Wide ranges of LLOD and collection event numbers were reported for B-ALL and plasma cell myeloma. Most laboratories determine LLOD by using dilutional studies and include it in final reports; a higher proportion of LAP participants used these practices than nonparticipants. CONCLUSIONS.­: Several MRD testing aspects vary among laboratories receiving FL3 Proficiency Testing materials. After the survey in 2014, new checklist items were implemented. As compared to 2014, fewer laboratories are performing MRD studies. While LLOD remains heterogeneous, a high proportion of LAP subscribers follow the new checklist requirements and, overall, target LLOD recommendations from disease-specific working groups are met.

Plasmablastic Lymphomas: Characterization of Tumor Microenvironment Using CD163 and PD-1 Immunohistochemistry.

This study aims to characterize the tumor microenvironment of plasmablastic lymphoma (PBL) in regard to the quantities of CD163(+) tumor associated macrophages (TAM) and PD1(+) tumor infiltrating lymphocytes (TIL). This article also reviews the existing knowledge of the role of PD-1/PD-L1 pathway in the tumor microenvironment of hematopoietic neoplasms, discusses potential mechanisms to explain our findings, and outlines areas for future studies. We performed CD163 and PD1 immunohistochemical studies in 11 cases classified as plasmablastic lymphoma, and recorded the percentages of positive TAMs and TILs. Based on previous studies, cut off values of ≥30% and >5% were used to classify the cases into high TAMs and TILs, respectively. We determined that the majority of cases (8 of 11, or 73%) had high percentage of TAMs, while only a minority had high percentage of TILs (3 of 11, or 27%). Our data shows a trend towards a negative correlation between TAMs and TILs (p=0.08), and a predominance of the pattern TAMhigh/TILlow (7 of 11, or 63%) compared to other patterns. The microenvironment of plasma-blastic lymphoma tends to show high percentage of TAMs (≥30%) combined with low percentage of TILs (≤5%). Additional studies are needed to determine the clinical significance of TILs and the influence of EBV and HIV infections on numbers of TILs in PBL. As high microenvironment TAMs have been associated with high microenvironment PD-L1 in other hematopoietic malignancies, our data supports the need for future studies on the expression of PD-L1 in PBL.

Pulmonary Nodular Lymphoid Hyperplasia.

Pulmonary nodular lymphoid hyperplasia is an uncommon reactive lymphoproliferative disorder that presents as an asymptomatic lung mass. The histopathologic diagnosis of pulmonary nodular lymphoid hyperplasia may be challenging because of its morphologic overlap with other diseases, such as extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue and immunoglobulin G4-related sclerosing disease. Despite the similarities, there are distinctive morphologic and phenotypic features that allow for the correct diagnosis in the majority of cases. This review aims to discuss the clinicopathologic features of pulmonary nodular lymphoid hyperplasia and contrast them with its histopathologic mimickers.

Langerhans Cell Histiocytosis of the Nasal Mucosa.

This case report describes a female patient in her early 40s with left-sided cervical lymphadenopathy, facial swelling, nasal congestion, and a left nasal mass.