p53 immunohistochemistry as an ancillary tool for rapid assessment of residual disease in TP53-mutated acute myeloid leukemia and myelodysplastic syndromes.

OBJECTIVES: Measurable residual disease flow cytometry (MRD-FC) and molecular studies are the most sensitive methods for detecting residual malignant populations after therapy for TP53-mutated acute myeloid leukemia and myelodysplastic neoplasms (TP53+ AML/MDS). However, their sensitivity is limited in suboptimal aspirates or when the immunophenotype of the neoplastic blasts overlaps with erythroids or normal maturing myeloid cells. In this study, we set out to determine if p53 immunohistochemistry (IHC) correlates with MRD-FC and next-generation sequencing (NGS) in the posttherapy setting and to determine the utility of p53 IHC to detect residual disease in the setting of negative or equivocal MRD-FC. METHODS: We retrospectively identified 28 pre- and posttherapy bone marrow biopsy specimens from 9 patients with TP53+ AML/MDS and a p53 overexpressor phenotype by IHC (strong 3+ staining at initial diagnosis). Next-generation sequencing and/or MRD-FC results were collected for each specimen. RESULTS: Using a threshold of more than ten 2-3+ cells in any one 400× field, p53 IHC detected residual disease with a sensitivity of 94% and a specificity of 89%. The threshold used in this study showed a high degree of concordance among 6 blinded pathologists (Fleiss κ = 0.97). CONCLUSIONS: Our study suggests that p53 IHC can be used as a rapid tool (within 24 hours) to aid in the detection of residual disease that may complement MRD-FC or NGS in cases in which the flow cytometry immunophenotype is equivocal and/or the bone marrow aspirate is suboptimal.

Epstein-Barr virus-associated post-transplant lymphoproliferative disorders in pediatric transplantation: A prospective multicenter study in the United States.

BACKGROUND: Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative disorders (PTLD) is the most common malignancy in children after transplant; however, difficulties for early detection may worsen the prognosis. METHODS: The prospective, multicenter, study enrolled 944 children (≤21 years of age). Of these, 872 received liver, heart, kidney, intestinal, or multivisceral transplants in seven US centers between 2014 and 2019 (NCT02182986). In total, 34 pediatric EBV+ PTLD (3.9%) were identified by biopsy. Variables included sex, age, race, ethnicity, transplanted organ, EBV viral load, pre-transplant EBV serology, immunosuppression, response to chemotherapy and rituximab, and histopathological diagnosis. RESULTS: The uni-/multivariable competing risk analyses revealed the combination of EBV-seropositive donor and EBV-naïve recipient (D+R-) was a significant risk factor for PTLD development (sub-hazard ratio: 2.79 [1.34-5.78], p = .006) and EBV DNAemia (2.65 [1.72-4.09], p < .001). Patients with D+R- were significantly more associated with monomorphic/polymorphic PTLD than those with the other combinations (p = .02). Patients with monomorphic/polymorphic PTLD (n = 21) had significantly more EBV DNAemia than non-PTLD patients (p < .001) and an earlier clinical presentation of PTLD than patients with hyperplasias (p < .001), within 6-month post-transplant. Among non-liver transplant recipients, monomorphic/polymorphic PTLD were significantly more frequent than hyperplasias in patients ≥5 years of age at transplant (p = .01). CONCLUSIONS: D+R- is a risk factor for PTLD and EBV DNAemia and associated with the incidence of monomorphic/polymorphic PTLD. Intensive follow-up of EBV viral load within 6-month post-transplant, especially for patients with D+R- and/or non-liver transplant recipients ≥5 years of age at transplant, may help detect monomorphic/polymorphic PTLD early in pediatric transplant.

The clinical, molecular, and prognostic features of the 2022 WHO and ICC classification systems for myelodysplastic neoplasms.

Myelodysplastic neoplasms (MDS) are clonal disorders of bone marrow failure exhibiting a variable risk of progression to acute myeloid leukemia. MDS exhibit certain prognostic genetic or cytogenetic abnormalities, an observation that has led to both the pathologic reclassification of MDS in the 2022 World Health Organization (WHO) and International Consensus Classification (ICC) systems, as well as to an updated prognostic schema, the Molecular International Prognostic Scoring System (IPSS-M). This single-institution study characterized the molecular patterns and clinical outcomes associated with the 2022 WHO and ICC classification schemas to assess their clinical utility. Strikingly, with the exception of one individual, all 210 patients in our cohort were classified into analogous categories by the two pathologic/diagnostic schemas. Most patients (70%) were classified morphologically while the remaining 30% had genetically classified disease by both criteria. Prognostic risk, as assessed by the IPSS-M score was highest in patients with MDS with biallelic/multi-hit TP53 mutations and lowest in pts with MDS-SF3B1. Median leukemia-free survival (LFS) was shortest for those with MDS with biallelic/multi-hit TP53 (0.7 years) and longest for those with MDS with low blasts (LFS not reached). These data demonstrate the clear ability of the 2022 WHO and ICC classifications to organize MDS patients into distinct prognostic risk groups and further show that both classification systems share more similarities than differences. Incorporation of the IPSS-M and IPSS-R features provide additive prognostic and survival components to both the WHO and ICC classifications, which together enhance their utility for evaluating and treating MDS patients.

Mutations in latent membrane protein 1 of Epstein-Barr virus are associated with increased risk of posttransplant lymphoproliferative disorder in children.

Epstein-Barr virus (EBV)-positive posttransplant lymphoproliferative disorder (PTLD) results in significant morbidity and mortality in pediatric transplant recipients. Identifying individuals at an increased risk of EBV-positive PTLD could influence clinical management of immunosuppression and other therapies, improving posttransplant outcomes. A 7-center prospective, observational clinical trial of 872 pediatric transplant recipients evaluated the presence of mutations at positions 212 and 366 of EBV latent membrane protein 1 (LMP1) as an indicator of risk of EBV-positive PTLD (clinical trials: NCT02182986). DNA was isolated from peripheral blood of EBV-positive PTLD case patients and matched controls (1:2 nested case:control), and the cytoplasmic tail of LMP1 was sequenced. Thirty-four participants reached the primary endpoint of biopsy-proven EBV-positive PTLD. DNA was sequenced from 32 PTLD case patients and 62 matched controls. Both LMP1 mutations were present in 31 of 32 PTLD cases (96.9%) and in 45 of 62 matched controls (72.6%) (P = .005; OR = 11.7; 95% confidence interval, 1.5, 92.6). The presence of both G212S and S366T carries a nearly 12-fold increased risk of development of EBV-positive PTLD. Conversely, transplant recipients without both LMP1 mutations carry a very low risk of PTLD. Analysis of mutations at positions 212 and 366 of LMP1 can be informative in stratifying patients for risk of EBV-positive PTLD.

Rapid Deployment of Whole Slide Imaging for Primary Diagnosis in Surgical Pathology at Stanford Medicine: Responding to Challenges of the COVID-19 Pandemic.

CONTEXT.­: Stanford Pathology began stepwise subspecialty implementation of whole slide imaging (WSI) in 2018 soon after the first US Food and Drug Administration approval. In 2020, during the COVID-19 pandemic, the Centers for Medicare & Medicaid Services waived the requirement for pathologists to perform diagnostic tests in Clinical Laboratory Improvement Amendments (CLIA)-licensed facilities. This encouraged rapid implementation of WSI across all surgical pathology subspecialties. OBJECTIVE.­: To present our experience with validation and implementation of WSI at a large academic medical center encompassing a caseload of more than 50 000 cases per year. DESIGN.­: Validation was performed independently for 3 subspecialty services with a diagnostic concordance threshold above 95%. Analysis of user experience, staffing, infrastructure, and information technology was performed after department-wide expansion. RESULTS.­: Diagnostic concordance was achieved in 96% of neuropathology cases, 100% of gynecologic pathology cases, and 98% of immunohistochemistry cases. After full implementation, 8 high-capacity scanners were operational, with whole slide images generated on greater than 2000 slides per weekday, accounting for approximately 80% of histologic slides at Stanford Medicine. Multiple modifications in workflow and information technology were needed to improve performance. Within months of full implementation, most attending pathologists and trainees had adopted WSI for primary diagnosis. CONCLUSIONS.­: WSI across all surgical subspecialities is achievable at scale at an academic medical center; however, adoption required flexibility to adjust workflows and develop tailored solutions. WSI at scale supported the health and safety of medical staff while facilitating high-quality patient care and education during COVID-19 restrictions.

Lupus erythematosus cells in a bone marrow aspirate.

A teenage girl presented with fevers of unknown origin and pancytopenia. Complete blood count showed anemia (hemoglobin, 9.0 g/dL), neutropenia (1.7 × 109/L), and thrombocytopenia (66 × 109/L). The bone marrow was hypocellular with left shifted hematopoiesis and myeloid hypoplasia. Aspirate smears were notable for a prominent population of neutrophils with crescentic nuclei that engulfed blue amorphous material (Fig. 1 panels A and B, Wright-Giemsa, magnification × 1000). The trephine biopsy showed similar cells with crescentic nuclei and eosinophilic material (Fig. 1 panels C and D, hematoxylin and eosin × 400). Flow cytometry was negative for an abnormal population. EBV by in situ hybridization and parvovirus immunohistochemistry were negative. Subsequent serologic testing was positive for ANA (1:1280), low C3/C4, anti-dsDNA, anti-SM and anti-B2GP1. A kidney biopsy demonstrated findings consistent with class III lupus nephritis.

Host microRNAs are decreased in pediatric solid-organ transplant recipients during EBV+ Post-transplant Lymphoproliferative Disorder.

Post-transplant lymphoproliferative disorder (PTLD) is a serious complication of solid organ transplantation. Predisposing factors include primary Epstein-Barr virus (EBV) infection, reactivation of EBV in recipient B cells, and decreased T cell immunity due to immunosuppression. In our previous studies EBV infection was demonstrated to markedly alter the expression of host B cell microRNA (miR). Specifically, miR-194 expression was uniquely suppressed in EBV+ B cell lines from PTLD patients and the 3'untranslated region of IL-10 was determined to be targeted by miR-194. Although EBV has been shown to regulate host miR expression in B cell lymphoma cell lines, the expression of miRs in the circulation of patients with EBV-associated PTLD has not been studied. The objective of this study was to determine if changes in miR expression are associated with EBV+ PTLD. In this study, we have shown that miR-194 is significantly decreased in EBV+PTLD tumors and that additional miRs, including miRs-17, 19 and 106a are also reduced in EBV+PTLD as compared to EBV-PTLD. We quantitated the levels of miRs-17, 19, 106a, 155, and 194 in the plasma and extracellular vesicles (EV; 50-70 nm as determined by nanoparticle tracking analysis) from pediatric recipients of solid organ transplants with EBV+ PTLD+ that were matched 1:2 with EBV+ PTLD- pediatric transplant recipients as part of the NIH-sponsored Clinical Trials in Organ Transplantation in Children, (CTOTC-06) study. Levels of miRs-17, 19, 106a, and 194 were reduced in the plasma and extracellular vesicles (EV) of EBV+ PTLD+ group compared to matched controls, with miRs-17 (p = 0.034; plasma), miRs-19 (p = 0.029; EV) and miR-106a (p = 0.007; plasma and EV) being significantly reduced. Similar levels of miR-155 were detected in the plasma and EV of all pediatric SOT recipients. Importantly, ~90% of the cell-free miR were contained within the EV supporting that EBV+ PTLD tumor miR are detected in the circulation and suggesting that EVs, containing miRs, may have the potential to target and regulate cells of the immune system. Further development of diagnostic, mechanistic and potential therapeutic uses of the miRs in PTLD is warranted.

Histiocytic Sarcoma With CCND1 Gene Rearrangement Clonally Related and Transdifferentiated From Mantle Cell Lymphoma.

OBJECTIVES: Histiocytic neoplasms demonstrate shared gene translocations and clonal immunoglobulin gene rearrangements in cases of associated B-cell lymphomas. However, the evolution of these related disease processes remains largely uncertain, especially in the setting of a prior mantle cell lymphoma. METHODS: We describe a unique case of a histiocytic sarcoma that transdifferentiated from blastoid mantle cell lymphoma after extensive therapy. Cytogenic and molecular studies were performed and provided evidence for clonal progression. RESULTS: We present the first reported case of a patient with blastoid mantle cell lymphoma harboring a CCND1 rearrangement that progressed despite multiple therapeutic regimens and ultimately transdifferentiated into histiocytic sarcoma. The histiocytic sarcoma demonstrated a CCND1 rearrangement and targeted next-generation sequencing showed a pathogenic variant in NRAS, a gene involved in the RAS/MAPK pathway, known to play a role in the pathogenesis of histiocytic sarcomas. TP53, NOTCH2, CREBBP, and NFKBIE variants were also identified, which are often seen in B-cell lymphomas, while rarely described in histiocytic sarcoma. CONCLUSIONS: To our knowledge, this is the first report to provide evidence for clonal evolution of histiocytic sarcoma from blastoid mantle cell lymphoma based on cytogenic and molecular findings. The patient's protracted therapeutic course may have acted as an evolutionary driver promoting this transdifferentiation process.

Human Germinal Center-associated Lymphoma (HGAL) Is a Reliable Marker of Normal and Neoplastic Follicular Helper T Cells Including Angioimmunoblastic T-Cell Lymphoma.

The diagnosis of angioimmunoblastic T-cell lymphoma (AITL) is complex and requires the demonstration of a T-follicular helper (TFH) phenotype. Immunophenotypic markers that detect the TFH phenotype are highly variable, thereby necessitating the use of 3 to 5 TFH markers to substantiate a TFH phenotype. We tested the utility of germinal center markers human germinal center-associated lymphoma (HGAL) and LIM-domain only 2 (LMO2) in detecting a TFH phenotype. We compared their staining to that of 6 TFH markers in current use, PD-1, ICOS, CXCL13, SAP, CD10, and BCL6, in a cohort of 23 AITL. Our results show that although both markers can detect a TFH phenotype, HGAL was superior to LMO2 in the percent of cells stained and the intensity of staining, 2 variables used to generate H-scores. Using H-scores as the metric, HGAL was most comparable to BCL6 among the currently used TFH markers and was more sensitive than CXCL13, SAP, CD10, and LMO2. PD-1 and ICOS emerged as the most robust of the 8 markers tested in this study in detecting a TFH phenotype. We conclude that HGAL is a reliable marker of TFH cells and can aid in the diagnosis of lymphomas of TFH derivation, particularly in the recognition of early patterns of AITL.

Angioimmunoblastic T-cell lymphoma diagnosed from pleural fluid by integration of morphologic, immunophenotypic, and molecular findings.

An 88-year-old man with end-stage renal disease on hemodialysis presented with shortness of breath and was found to have lower extremity edema and bilateral pleural effusions on a chest X-ray. A therapeutic and diagnostic thoracentesis was performed, and cytologic examination revealed atypical mononuclear cells. Based on this, flow cytometry was performed on the pleural fluid, along with immunostains on the cellblock and a next-generation sequencing (NGS) panel. A definitive diagnosis of angioimmunoblastic T-cell lymphoma (AITL) was made based on demonstrating an atypical T follicular helper cell population expressing CD10, BCL6, CXCL13, CD200, CD57, and PD1, and detection of pathogenic variants in RHOA, IDH2, and TET2. This case represents the first reported case where a primary diagnosis of AITL was made on a body fluid specimen and highlights how immunophenotyping and NGS can provide a definitive diagnosis of AITL on a cytologic specimen.

Reactive Eosinophil Proliferations in Tissue and the Lymphocytic Variant of Hypereosinophilic Syndrome.

OBJECTIVES: The 2019 Society for Hematopathology and European Association for Haematopathology Workshop reviewed the spectrum of neoplastic, nonneoplastic, and borderline entities associated with reactive eosinophilia in tissue. METHODS: The workshop panel reviewed 46 cases covered in 2 workshop sessions. RESULTS: The 46 cases were presented with their consensus diagnoses during the workshop. Reactive eosinophilia in lymph nodes and other tissues may be accompanied by or be distinct from peripheral blood eosinophilia. Reactive etiologies included inflammatory disorders such as Kimura disease and IgG4-related disease, which may show overlapping pathologic features and reactions to infectious agents and hypersensitivity (covered in a separate review). Hodgkin, T-cell, and B-cell lymphomas and histiocytic neoplasms can result in reactive eosinophilia. The spectrum of these diseases is discussed and illustrated through representative cases. CONCLUSIONS: Reactive eosinophilia in lymph nodes and tissues may be related to both nonneoplastic and neoplastic lymphoid proliferations and histiocytic and nonhematolymphoid processes. Understanding the differential diagnosis of reactive eosinophilia and the potential for overlapping clinical and pathologic findings is critical in reaching the correct diagnosis so that patients can be treated appropriately.

What's in a band? The function of the color and banding pattern of the Banded Swallowtail.

Butterflies have evolved a diversity of color patterns, but the ecological functions for most of these patterns are still poorly understood. The Banded Swallowtail butterfly, Papilio demolion demolion, is a mostly black butterfly with a greenish-blue band that traverses the wings. The function of this wing pattern remains unknown. Here, we examined the morphology of black and green-blue colored scales, and how the color and banding pattern affects predation risk in the wild. The protective benefits of the transversal band and of its green-blue color were tested via the use of paper model replicas of the Banded Swallowtail with variations in band shape and band color in a full factorial design. A variant model where the continuous transversal green-blue band was shifted and made discontinuous tested the protective benefit of the transversal band, while grayscale variants of the wildtype and distorted band models assessed the protective benefit of the green-blue color. Paper models of the variants and the wildtype were placed simultaneously in the field with live baits. Wildtype models were the least preyed upon compared with all other variants, while gray models with distorted bands suffered the greatest predation. The color and the continuous band of the Banded Swallowtail hence confer antipredator qualities. We propose that the shape of the band hinders detection of the butterfly's true shape through coincident disruptive coloration; while the green color of the band prevents detection of the butterfly from its background via differential blending. Differential blending is aided by the green-blue color being due to pigments rather than via structural coloration. Both green and black scales have identical structures, and the scales follow the Bauplan of pigmented scales documented in other Papilio butterflies.

Myeloid Cell Nuclear Differentiation Antigen (MNDA) Positivity in Primary Follicles: Potential Pitfall in the Differential Diagnosis With Marginal Zone Lymphoma.

Myeloid cell nuclear differentiation antigen (MNDA) is an immunohistochemical marker that is used to distinguish marginal zone lymphomas (MZLs) from other small B-cell lymphomas. An index case that showed MNDA staining in primary follicles prompted the current study to evaluate whether MNDA expression is widespread in primary follicles and to address whether it poses a potential diagnostic pitfall. Of the 15 cases with primary follicles identified by a search of the laboratory information system, 7 had positive MNDA staining. In all cases, there was weak nuclear staining similar to what is typical of MNDA staining in MZLs. All cases showed intense nuclear signal in myeloid lineage cells such as neutrophils, which served as positive internal controls. The histologic and cytologic features of primary follicles and MZLs showed overlapping features, particularly in small biopsies. Our results indicate that weak nuclear MNDA staining can act as a potential pitfall in the evaluation of small B-cell lymphomas. Correlation with other immunohistochemical markers that are useful in the workup of small B-cell lymphomas, as well as those that outline immunoarchitectural features of lymphoid follicles, is suggested when both entities are part of the differential diagnosis. Our results underscore the need for caution in the interpretation of weak nuclear MNDA staining in the evaluation of small B-cell lymphomas.

Implementation of Epic Beaker Clinical Pathology at Stanford University Medical Center.

OBJECTIVES: To provide an account of implementation of the Epic Beaker 2014 clinical pathology module at Stanford University Medical Center and highlight strengths and weaknesses of the system. METHODS: Based on a formal selection process, Stanford selected Epic Beaker to replace Sunquest as the clinical laboratory information system (LIS). The rationale included integration between the LIS and already installed Epic electronic medical record (EMR), reduction in the number of systems and interfaces, and positive patient identification (PPID). The build was significantly customized and included a first of its kind Epic-to-Epic interface. This was due to the clinical laboratory serving two hospitals (pediatric and adult) with independent instances of Epic. RESULTS: Test turnaround times showed improvement from historical baselines, mostly because of the implementation of PPID. PPID also resulted in significant reduction in mislabeled specimens. CONCLUSIONS: Epic 2014 Beaker clinical pathology is a viable LIS with adequate functionality for a large academic center. Strengths include PPID and integration with the EMR. Integration provides laboratory users with ready access to the patient's relevant clinical history to assist releasing of results and gives physician and nurse providers sophisticated add-on ordering and specimen collection workflows. Areas that could use further development include specimen aliquoting, quality control reporting, and maintenance tools.

Primary lymphoma of bone in the pediatric and young adult population.

Primary lymphoma of bone (PLB) accounts for 3% to 7% of primary neoplasms of bone and must be distinguished from more common bone tumors in the pediatric population such as osteosarcoma, Ewing sarcoma, and other small round blue cell tumors. In this study, pathology databases from 4 institutions were queried for PLB in individuals 1 to 21 years old. A total of 54 cases of PLB were identified, including 41 diffuse large B-cell lymphomas (DLBCL, 76%), 8 B-lymphoblastic lymphomas (BLL, 15%), 3 anaplastic large cell lymphomas (ALCL, 6%), and 2 low-grade follicular lymphomas (4%). The male/female ratio was 1.8:1 and median age was 16 years (range, 2-21). Patients with DLBCL were significantly older (P<.001), and patients with ALCL and BLL were significantly younger (P=.050 and P=.008, respectively) when compared with the other patients. Due to necrosis, crush artifact, and/or insufficient material, 30% of cases required multiple biopsies for diagnosis. The femur, tibia, pelvic bones, humerus, and vertebrae were most commonly involved. DLBCL patients had significantly more solitary bone involvement (P=.001), whereas BLL had significantly more polyostotic involvement (P<.001). Of the 37 patients with outcome data, all had no evidence of disease on last follow-up. This largest pediatric series of PLB identifies DLBCL as the most frequent subtype and documents rarer occurrences of BLL, ALCL, and follicular lymphomas. The differential diagnosis of bone neoplasms in pediatric patients, including those with necrosis, should include PLB.