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.

Artificial Intelligence for Clinical Flow Cytometry.

In this review, the authors discuss the fundamental principles of machine learning. They explore recent studies and approaches in implementing machine learning into flow cytometry workflows. These applications are promising but not without their shortcomings. Explainability may be the biggest barrier to adoption, as they contain "black boxes" in which a complex network of mathematical processes learns features of data that are not translatable into real language. The authors discuss the current limitations of machine learning models and the possibility that, without a multiinstitutional development process, these applications could have poor generalizability. They also discuss widespread deployment of augmented decision-making.

TYMS promotes genomic instability and tumor progression in Ink4a/Arf null background.

We previously showed that elevated TYMS exhibits oncogenic properties and promotes tumorigenesis after a long latency, suggesting cooperation with sequential somatic mutations. Here we report the cooperation of ectopic expression of human TYMS with loss of Ink4a/Arf, one of the most commonly mutated somatic events in human cancer. Using an hTS/Ink4a/Arf -/- genetically engineered mouse model we showed that deregulated TYMS expression in Ink4a/Arf null background accelerates tumorigenesis and metastasis. In addition, tumors from TYMS-expressing mice were associated with a phenotype of genomic instability including enhanced double strand DNA damage, aneuploidy and loss of G1/S checkpoint. Downregulation of TYMS in vitro decreased cell proliferation and sensitized tumor cells to antimetabolite chemotherapy. In addition, depletion of TYMS in vivo by TYMS shRNA reduced tumor incidence, delayed tumor progression and prolonged survival in hTS/Ink4a/Arf -/- mice. Our data shows that activation of TYMS in Ink4a/Arf null background enhances uncontrolled cell proliferation and tumor growth, supporting the development of new agents and strategies targeting TYMS to delay tumorigenesis and prolong survival.

First-in-class multifunctional TYMS nonclassical antifolate inhibitor with potent in vivo activity that prolongs survival.

Although thymidylate synthase (TYMS) inhibitors have served as components of chemotherapy regimens, the currently available inhibitors induce TYMS overexpression or alter folate transport/metabolism feedback pathways that tumor cells exploit for drug resistance, limiting overall benefit. Here we report a small molecule TYMS inhibitor that i) exhibited enhanced antitumor activity as compared with current fluoropyrimidines and antifolates without inducing TYMS overexpression, ii) is structurally distinct from classical antifolates, iii) extended survival in both pancreatic xenograft tumor models and an hTS/Ink4a/Arf null genetically engineered mouse tumor model, and iv) is well tolerated with equal efficacy using either intraperitoneal or oral administration. Mechanistically, we verify the compound is a multifunctional nonclassical antifolate, and using a series of analogs, we identify structural features allowing direct TYMS inhibition while maintaining the ability to inhibit dihydrofolate reductase. Collectively, this work identifies nonclassical antifolate inhibitors that optimize inhibition of thymidylate biosynthesis with a favorable safety profile, highlighting the potential for enhanced cancer therapy.

Pericardial Effusion: A Novel Presentation of Aplastic Anemia.

Pericardial effusion is defined as the accumulation of fluid between the visceral and parietal pericardium. The underlying etiology varies as any pathology that causes pericarditis or involves the pericardium can cause effusion. In practice, the majority of pericarditis cases are idiopathic, although these are assumed to be secondary to occult viral infection or inflammatory phenomena. Malignancy, particularly the metastatic spread of noncardiac primary tumors, has been implicated as a differential in the diagnosis of pericardial effusion. Though commonly seen in solid malignancies, effusion has been reported in hematologic malignancies such as myelodysplastic syndrome (MDS), acute leukemia, and lymphoma. Nonetheless, pericardial effusions associated with hematologic conditions are extremely rare with only one case report published describing pericardial effusion secondary to immune thrombocytopenia (ITP). We herein report the first documented case, to our knowledge, of pericardial effusion as an initial clinical manifestation of aplastic anemia in a middle-aged male presenting with pancytopenia.

Pathology Education Powered by Virtual and Digital Transformation: Now and the Future.

CONTEXT.­: Myriad forces are changing teaching and learning strategies throughout all stages and types of pathology education. Pathology educators and learners face the challenge of adapting to and adopting new methods and tools. The digital pathology transformation and the associated educational ecosystem are major factors in this setting of change. OBJECTIVE.­: To identify and collect resources, tools, and examples of educational innovations involving digital pathology that are valuable to pathology learners and teachers at each phase of professional development. DATA SOURCES.­: Sources were a literature review and the personal experience of authors and educators. CONCLUSIONS.­: High-quality digital pathology tools and resources have permeated all the major niches within anatomic pathology and are increasingly well applied to clinical pathology for learners at all levels. Coupled with other virtual tools, the training landscape in pathology is highly enriched and much more accessible than in the past. Digital pathology is well suited to the demands of peer-to-peer education, such as in the introduction of new testing, grading, or other standardized practices. We found that digital pathology was well adapted to apply our current understanding of optimal teaching strategies and was effective at the undergraduate, graduate, postgraduate, and peer-to-peer levels. We curated and tabulated many existing resources within some segments of pathology. We identified several best practices for each training or educational stage based on current materials and proposed high-priority areas for potential future development.

Wrong Tissue in Block.

OBJECTIVES: Maintaining specimen identity during surgical pathology tissue processing is critical. Epic Beaker Laboratory Information System requires sequential scanning of specimen label and grossed blocks (block confirmation) to ensure specimen identity. We report our institution's experience with wrong tissue in block (WTIB) grossing errors before and after adopting block confirmation. METHODS: During the first 18 months of Beaker implementation, block confirmation was not required. We then mandated block confirmation for a 3-month period. To ensure compliance, we then built a "hard stop" feature that prevents scanning any unconfirmed blocks onto a packing list. We reviewed WTIB incidents pre- and postimplementation of these solutions. RESULTS: Before using block confirmation, we had WTIB incidents involving 17 (0.043%) of 38,848 cases. When we mandated block confirmation use, we had WTIB involving 2 (0.043%) of 4,646 cases. After implementing the hard stop feature, we had WTIB incidents involving 2 (0.005%) of 42,411 cases. Overall, there was an 88.4% (0.043% vs 0.005%; P < .001) reduction in WTIB incidents using block confirmation with a hard stop. CONCLUSIONS: Beaker is a customizable platform that can be tailored to a laboratory's workflow. By using barcoding, implementing custom-built features, and improving workflow protocols, we significantly reduced WTIB errors.

Maternal Hematologic Neoplasms during Pregnancy: Histologic Findings in the Placenta.

Placental metastasis of maternal neoplasms is well documented in solid tumors, unlike hematologic neoplasms. We reviewed placental findings from deliveries complicated by maternal hematologic neoplasms exploring the prevalence and patterns of placental transmission and insufficiency. In the 8-yr study period, 11 cases were analyzed. Acute myeloid leukemia was the most common diagnosis (4/11, 36%). Seven cases (63%) showed no evidence of placental spread of neoplasm, while four cases (36%) showed placental spread, restricted to the maternal compartment. Maternal vascular malperfusion was documented in 8/11 (72%) cases. Neonatal follow up was available in 10 cases, all children were alive and well.

Bronchoalveolar lavage fluid review in acute promyelocytic leukemia differentiation syndrome.

The patient was a 62-year-old Caucasian man with blood smear and flow cytometry concerning for acute promyelocytic leukemia with FISH ultimately confirming PML-RARA translocation. He had a 30-year history of employment at a nuclear power plant. He presented with diffuse intravascular coagulation, hyperleukocytosis, and quickly developed acute respiratory distress syndrome. On day four of ATRA + Hydrea, a bronchoalveolar lavage was performed and was non-bloody. On microscopic fluid review, abnormal immature cells with bilobed nuclear contours were identified, similar in morphology to those seen on the diagnostic blood smear review, amidst background alveolar-type macrophages. Subsequent flow cytometric analysis showed these cells to be abnormal promyelocytes; however, they differed from the blood flow cytometry study performed prior to initiation of ATRA by showing maturational immunophenotypic changes. While the leukemic promyelocytes on bronchoalveolar lavage were morphologically immature, these immunophenotypic changes somewhat recapitulated those seen in normal granulocyte maturation and were thus suggestive of so-called differentiation syndrome. Unfortunately, the patient passed away during induction chemotherapy due to complications from diffuse intravascular coagulation and differentiation syndrome. Important pathobiological information can be gathered from fluid review and concomitant flow cytometric analysis.

Informatics driven quality improvement in the modern histology lab.

Laboratory Information Systems (LIS) and data visualization techniques have untapped potential in anatomic pathology laboratories. Pre-built functionalities of LIS do not address all the needs of a modern histology laboratory. For instance, "Go live" is not the end of LIS customization, but just the beginning. After closely evaluating various histology lab workflows, we implemented several custom data analytics dashboards and additional LIS functionalities to monitor and address weaknesses. Herein, we present our experience in LIS and data-tracking solutions that improved trainee education, slide logistics, staffing/instrumentation lobbying, and task tracking. The latter was addressed through the creation of a novel "status board" akin to those seen in inpatient wards. These use-cases can benefit other histology laboratories.

Progressive hypoventilation due to mixed CD8+ and CD4+ lymphocytic polymyositis following tremelimumab - durvalumab treatment.

BACKGROUND: The combination of CTLA-4 and PD-L1 inhibitors has a manageable adverse effect profile, although rare immune-related adverse events (irAE) can occur. CASE PRESENTATION: We describe an autoimmune polymyositis following a partial response to combination tremelimumab and durvalumab for the treatment of recurrent lung adenocarcinoma. Radiography revealed significant reduction in all metastases; however, the patient developed progressive neuromuscular hypoventilation due to lymphocytic destruction of the diaphragmatic musculature. Serologic testing revealed a low level of de novo circulating antibodies against striated muscle fiber. Immunohistochemistry revealed type II muscle fiber atrophy with a mixed CD8+ and CD4+ lymphocyte infiltrate, indicative of inflammatory myopathy. CONCLUSIONS: This case supports the hypothesis that muscle tissue is a target for lymphocytic infiltration in immune checkpoint inhibitor-associated polymyositis. Further insights into the autoimmune mechanism of PM will hopefully contribute to the prevention and treatment of this phenomenon.

A practical approach to diagnose soft tissue myeloid sarcoma preceding or coinciding with acute myeloid leukemia.

Myeloid sarcoma involving soft tissue is rare and may present a pathologic diagnostic challenge, particularly when it precedes or coincides with hematological malignancies. Furthermore, it may mimic non-Hodgkin lymphoma, poorly differentiated carcinoma, melanoma, or round blue cell tumors, which is a potential diagnostic pitfall. In addition to a retrospective review of myeloid sarcoma (MS) cases seen at our institution, we describe differential diagnoses, diagnostic pitfalls, and practical approaches to diagnosing soft tissue MS preceding or coinciding with acute myeloid leukemia. Our institutional retrospective review (1999-2011) of MSs identified 12 cases of MS in which there was no known blood or bone marrow involvement at diagnosis. A panel of immunohistochemical stains and/or flow cytometry was reviewed; marker selection was subject to the pathologist's discretion. These tumors were consistently positive for CD117 (9/9), CD43 (7/7), myeloperoxidase (8/10), CD68 (4/5), and CD34 (5/9) by flow cytometry and/or immunohistochemistry. We also described a referral case, which had classic MS morphology and a myelomonocytic immunophenotype including positivity for CD45, lysozyme, and CD117 with supporting molecular information. Based on our institution's experience and review of the literature, we recommend that when the index of suspicion for MS is high, an immunohistochemical stain and/or flow cytometry panel should include CD43, lysozyme, CD117, CD68, CD33, Human Leukocyte Antigen DR (HLA-DR), and myeloperoxidase, in addition to thorough review of the patient's history, cytogenetic studies, and proper discussion with the clinician.

Rhabdomyomatous differentiation in Wilms tumor pulmonary metastases: a case report and literature review.

While sparsely reported in the literature, Wilms tumor may differentiate into more mature mesenchymal tissue types, such as skeletal muscle, following chemotherapy. The frequency of this event is unknown. Chemotherapy and radiation may induce cytodifferentiation of Wilms tumor cells or select for the survival of less mitotically active cells. In follow-up biopsies, the presence of rhabdomyomatous differentiation can confound the histologic diagnosis. Furthermore, these differentiated tumors appear to be more resistant to chemotherapy, thus biopsy and positron emission tomography scans following chemotherapy and radiation may prevent unnecessary treatment. We report an unusual case of Wilms tumor in a 21- year-old man with rhabdomyomatous differentiation of pulmonary metastases after chemotherapy, which presented a challenge during frozen section diagnosis.