Immunophenotyping of chronic B-cell neoplasms: flow cytometry versus immunohistochemistry

Posterior Uveitis in Ocular-Involving Chronic Lymphocytic Leukemia and the Utility of Negative MYD88 L265P Testing in the Diagnosis

Introduction

The aim of this study was to investigate if a negative test result for MYD88 L265P mutation, associated with vitreoretinal lymphoma (VRL) and primary CNS lymphoma, in liquid biopsies from intraocular fluids can be a useful adjuvant test to diagnose chronic lymphocytic leukemia in clinically challenging cases.

Case Presentations

We selected patients with a past medical history or examinations findings suspicious for intraocular lymphoma. We evaluated both vitreous and aqueous humor-derived (AHD) MYD88 L265P mutation from patients that had suspected intraocular lymphoma that warranted a liquid biopsy procedure. Gold-standard cytopathology, flow cytometry, and gene rearrangement studies were also performed. All 4 patients had negative AHD MYD88 L265P mutation testing. Gold-standard testing (cytology) either showed paucicellular specimens (1/4) or specimens with high background inflammation (3/4). One case showed a rare B-cell clonal population (CD5+, Kappa-restricted by flow cytometry), but this was not sufficient to make any definitive diagnosis. All patients were subsequently initiated on systemic therapy and had improvement in their disease burden.

Conclusions

Negative AHD MYD88 L265P mutation testing can serve as an adjuvant molecular test to diagnose difficult cases of intraocular CLL.

Sudden death due to leukostasis in a subject with undiagnosed chronic lymphocytic leukemia

Sudden death due to leukostasis and lymphocyte thrombi in patients with chronic hematologic malignancies is rare. Leukostasis is characterized by highly elevated leukemic cell count and decreased tissue perfusion symptoms, leading to severe complications and even death. Chronic lymphocytic leukemia (CLL) is a chronic lymphoproliferative disorder that shows a highly heterogeneous clinical course, ranging from indolent form to very aggressive disease. Due to its low metabolic and mitotic rate, there is a lower incidence of clinically significant leukostasis in patients with CLL. Two main theories have been proposed in the development of leukostasis: (1) increased blood viscosity due to large leukemic cell populations; (2) high metabolic activity and cytokine production by leukemic cells. Both mechanisms lead to local hypoxic damage.We present a case of a 70-year-old man who died suddenly in the absence of symptoms. Autopsy and histology examinations revealed findings consistent with CLL and diffuse leukostasis involving the major organs' vessels.In the presence of gross and/or microscopic findings suggesting a potential hematologic malignancy, undiagnosed or relapsing hematologic malignancies should be considered in the differential diagnosis of sudden deaths.

Pulsed focused ultrasound can improve the anti-cancer effects of immune checkpoint inhibitors in murine pancreatic cancer

Pulsed high-intensity focused ultrasound (pHIFU) uses acoustic pressure to physically disrupt tumours. The aim of this study was to investigate whether pHIFU can be used in combination with immune checkpoint inhibitors (ICIs) to enhance survival of tumour-bearing animals. Murine orthotopic pancreatic KPC tumours were exposed both to a grid of pHIFU lesions (peak negative pressure = 17 MPa, frequency = 1.5 MHz, duty cycle = 1%, 1 pulse s-1, duration = 25 s) and to anti-CTLA-4/anti-PD-1 antibodies. Acoustic cavitation was detected using a weakly focused passive sensor. Tumour dimensions were measured with B-mode ultrasound before treatment and with callipers post-mortem. Immune cell subtypes were quantified with immunohistochemistry and flow cytometry. pHIFU treatment of pancreatic tumours resulted in detectable acoustic cavitation and increased infiltration of CD8+ T cells in the tumours of pHIFU and pHIFU + ICI-treated subjects compared with sham-exposed subjects. Survival of subjects treated with pHIFU + ICI was extended relative to both control untreated subjects and those treated with either pHIFU or ICI alone. Subjects treated with pHIFU + ICI had increased levels of CD8+IFNγ+ T cells, increased ratios of CD8+IFNγ+ to CD3+CD4+FoxP3+ and CD11b+Ly6G+ cells, and decreased CD11chigh cells in their tumours compared with controls. These results provide evidence that pHIFU combined with ICI may have potential for use in pancreatic cancer therapy.

Optimal panel of immunohistochemistry for the diagnosis of B-cell non-Hodgkin lymphoma using bone marrow biopsy: a tertiary care center study

Background

Morphological diagnosis of non-Hodgkin lymphoma (NHL) is usually based on lymph node biopsy. Bone marrow biopsy (BMB) is important for staging, and morphology alone can be challenging for subtyping. Immunohistochemistry (IHC) allows a more precise diagnosis and characterization of NHL using monoclonal antibodies. However, there is a need for a minimal panel that can provide maximum information at an affordable cost.

Methods

All newly diagnosed cases of B-cell NHL with bone marrow infiltration between 2017 and 2019 were included. BMB was the primary procedure for diagnosing B-cell NHL. Subtyping of lymphomas was performed by immunophenotyping using a panel of monoclonal antibodies on IHC. The primary diagnostic panel of antibodies for B-cell NHL included CD19, CD20, CD79, CD5, CD23, CD10, Kappa, and Lambda. The extended panel of antibodies for further subtyping included CD30, CD45, CD56, Cyclin D1, BCL2, and BCL6.

Results

All cases of B-cell NHL were classified into the chronic lymphocytic leukemia (CLL) and non-CLL groups based on morphology and primary IHC panel. In the CLL group, the most significant findings were CD5 expression, CD23 expression, dim CD79 expression, and weak surface immunoglobulin (Ig) positivity. In the non-CLL group, they were CD5 expression, positive or negative CD23 expression, strong CD79 expression, and strong surface Ig expression. An extended panel was used for further subtyping of non-CLL cases, which comprised CD10, Cyclin D1, BCL2, and BCL6.

Conclusion

We propose a two-tier approach for immunophenotypic analysis of newly diagnosed B-cell NHL cases with a minimum primary panel including CD5, CD23, CD79, Kappa, and Lambda for differentiation into CLL/non-CLL group and Kappa and Lambda for clonality assessment. An extended panel may be used wherever required for further subtyping of non-CLL.

Antibody-drug conjugates for previously treated aggressive lymphomas: focus on polatuzumab vedotin

INTRODUCTION

Antibody-drug conjugates (ADCs) are immunoconjugates and comprise a monoclonal antibody that is chemically attached to a cytotoxic drug (or payload) via a stable chemical linker. Since the approval of the first ADC in 2000, there are now nine different approved agents and over 100 ADCs in the drug-development pipeline.

AREAS COVERED

This review briefly describes the ADCs approved for treatment of lymphoma and their distinguishing factors in terms of target, linker and payload. The clinical implications of the use of ADCs are also considered. Here, we focus on polatuzumab vedotin, an ADC targeted to CD79b, which is approved for the treatment of patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) who have received at least one (EU approval) or two (US approval) prior therapies and are not eligible for bone marrow transplantation. The characteristics of polatuzumab vedotin are discussed and clinical data are presented. The future of polatuzumab vedotin clinical development, and ADCs in general, are also considered.

EXPERT OPINION

ADCs represent a significant advance in the treatment of lymphoma. Polatuzumab vedotin has shown clinical efficacy and a tolerable safety profile in both first-line and R/R DLBCL; future studies are planned to further investigate this ADC.

Immunophenotyping of Murine Precursor B-Cell Leukemia/Lymphoma: A Comparison of Immunohistochemistry and Flow Cytometry

In humans and in mouse models, precursor B-cell lymphoblastic leukemia (B-ALL)/lymphoblastic lymphoma (B-LBL) can be classified as either the pro-B or pre-B subtype. This is based on the expression of antigens associated with the pro-B and pre-B stages of B-cell development. Antigenic markers can be detected by flow cytometry or immunohistochemistry (IHC), but no comparison of results from these techniques has been reported for murine B-ALL/LBL. In our analysis of 30 cases induced by chemical or viral mutagenesis on a WT or Pax5+/- background, 18 (60%) were diagnosed as pro-B by both flow cytometry and IHC. Discordant results were found for 12 (40%); 6 were designated pro-B by IHC and pre-B by flow cytometry and the reverse for the remaining 6 cases. Discordance occurred because different markers were used to define the pro-B-to-pre-B transition by IHC vs flow cytometry. IHC expression of cytoplasmic IgM (μIgM) defined the pre-B stage, whereas the common practice of using CD25 as a surrogate marker in flow cytometry was employed here. These results show that CD25 and μIgM are not always concurrently expressed in B-ALL/LBL, in contrast to normal B-cell development. Therefore, when subtyping B-ALL/LBL in mice, an IHC panel of B220, PAX5, TdT, c-Kit/CD117, CD43, IgM, and ΚLC should be considered. For flow cytometry, cytoplasmic IgM may be an appropriate marker in conjunction with the surface markers B220, CD19, CD43, c-Kit/CD117, BP-1, and CD25.

Pathologic Findings in Bronchopulmonary Leukemic Infiltrates in Patients With Chronic Lymphocytic Leukemia

INTRODUCTION

Chronic lymphocytic leukemia (CLL) is the most common lymphoproliferative disorder worldwide. Although thoracic complications are frequent in CLL, only limited data exists regarding these complications. Pleural, parenchymal, and airway disease may occur owing to CLL itself, treatment-related adverse events, typical or opportunistic infections, or from preexisting comorbidities. The etiology of parenchymal infiltrates is often attributed to pneumonia and can be difficult to properly identify without a diagnostic procedure.

PATIENTS AND METHODS

We conducted a retrospective chart review of patients admitted from 2000 through 2016 with a diagnosis of CLL and abnormal radiography that underwent a bronchoscopy with biopsy, surgical lung biopsy, or transthoracic biopsies for nonresolving infiltrates after a course of antibiotics. We described the incidence of bronchopulmonary leukemic infiltrates (BPLI), describe other diagnosis achieved by the biopsy, and also describe the pathologic findings associated with BPLI in these patients.

RESULTS

There were 111 procedures performed on 98 patients that yielded a diagnosis in 82 patients. In 16 patients, no histologic or pathologic diagnosis was identified after the biopsy. BPLI was diagnosed in 32 (39%) cases. In 27 (85%) of 32 cases, the biopsies returned with only BPLI owing to CLL (without inflammation), whereas 5 (15%) of 32 cases showed concomitant acute or chronic inflammation.

CONCLUSION

Direct infiltration by leukemic cells may cause pulmonary symptoms and signs indistinguishable from infection. Biopsy is necessary to establish a definitive diagnosis, and physicians caring for these patients, including pathologists, should be aware of the clinicopathologic picture of BPLI to render an informative diagnosis.

Normal hematopoiesis and hematologic malignancies: role of canonical Wnt signaling pathway and stromal microenvironment

Wnts are a family of evolutionary-conserved secreted signaling molecules critically involved in a variety of developmental processes and in cell fate determination. A growing body of evidence suggests that Wnt signaling plays a crucial role in the influence of bone marrow stromal microenvironment on the balance between hematopoietic stem cell self-renewal and differentiation. Emerging clinical and experimental evidence also indicates Wnt signaling involvement in the disruption of the latter balance in hematologic malignancies, where the stromal microenvironment favors the homing of cancer cells to the bone marrow, as well as leukemia stem cell development and chemoresistance. In the present review, we summarize and discuss the role of the canonical Wnt signaling pathway in normal hematopoiesis and hematologic malignancies, with regard to recent findings on the stromal microenvironment involvement in these process and diseases.