A multimodal genomics approach to diagnostic evaluation of pediatric hematologic malignancies.

Detection of somatic genetic drivers is important for risk stratification and treatment selection in pediatric leukemias; however, newly recognized genetic markers may not be detected by routine karyotyping and fluorescence in situ hybridization (FISH). To identify the combination of assays that provides the highest detection rate for clinically significant molecular abnormalities, we tested 160 B- lymphoblastic leukemia (B-ALL) by karyotyping, FISH, chromosomal microarray analysis (CMA) and the custom next-generation sequencing (NGS) panel, OncoKidsⓇ. In addition, we tested 40 myeloid malignancies with karyotyping, chromosomal microarray analysis (CMA), and OncoKidsⓇ; 36/40 myeloid malignancies were also tested with FISH. In B-ALL, individual testing methods had the following diagnostic yields for the key genetic drivers: karyotype 34%; basic FISH panel 45%; FISH panel with IGH and CRLF2 probes 65%; CMA 48%; OncoKidsⓇ 39%. CMA and OncoKidsⓇ testing allowed detection of key genetic drivers in 42% of the samples that remained unknown upon testing by conventional methods. In myeloid malignancies, OncoKidsⓇ had the highest yield for detection of both primary and secondary DNA mutations and RNA fusions. Our data highlights the complementarity between CMA and NGS and conventional cytogenetics/FISH in pediatric leukemia diagnostics. Due to rapid turn-around-time, FISH may be useful as an initial screening method in B-ALL. Our data also suggests NGS testing with a comprehensive panel, despite a longer turnaround time, is a good alternative to karyotyping and FISH in pediatric AML due to its superior detection rate.

Bone Marrow Findings of Immune-Mediated Pure Red Cell Aplasia Following Anti-Programmed Cell Death Receptor-1 Therapy: A Report of Two Cases and Review of Literature.

Immune checkpoint inhibitors have recently emerged as important and effective advanced cancer treatment options. Programmed cell death receptor-1 (PD-1) antagonists such as pembrolizumab and nivolumab have been approved by the US Food and Drug Administration for treatment of many advanced cancers. As anti-PD-1 checkpoint inhibitor use has been increasing, previously unreported rare side effects emerge. These checkpoint inhibitors upregulate humoral and cellular immune responses to tumor antigens. Consequently, they can be associated with immune-related adverse events including hematological-related reactions such as autoimmune hemolytic anemia, immune thrombocytopenia, neutropenia and pancytopenia. However, pure red cell aplasia (PRCA) induced by anti-PD-1 checkpoint inhibitors is rarely reported in the literature. We herein report cases of two patients who developed PRCA during treatment with anti-PD-1 checkpoint inhibitors. In both cases, a peripheral blood smear examination demonstrated reticulocytopenia. Bone marrow biopsies revealed severe erythroid hypoplasia with maturation arrest at the proerythroblast stage, relative granulocytic hyperplasia and lymphocytosis. Flow cytometry and immunohistochemistry revealed that the lymphocytes were predominantly CD8+ T cells. T lymphocytosis, especially in one of the two patients, mimicked a T-cell lymphoproliferative disorder; lack of clonality indicated a reactive process. Our findings, in addition to data presented in the literature, suggest that T cells play a critical role in the pathogenesis of immune-related PRCA. PRCA is an under-recognized immune-mediated adverse event that does not manifest during the clinical trial phase. It is a potentially life-threatening complication, which should be considered in the differential diagnosis of anemia in patients treated with anti-PD-1 checkpoint inhibitors.

Trends in Bone Marrow Sampling and Core Biopsy Specimen Adequacy in the United States and Canada: A Multicenter Study.

OBJECTIVES: To assess bone marrow (BM) sampling in academic medical centers. METHODS: Data from 6,374 BM samples obtained in 32 centers in 2001 and 2011, including core length (CL), were analyzed. RESULTS: BM included a biopsy (BMB; 93%) specimen, aspirate (BMA; 92%) specimen, or both (83%). The median (SD) CL was 12 (8.5) mm, and evaluable marrow was 9 (7.6) mm. Tissue contraction due to processing was 15%. BMB specimens were longer in adults younger than 60 years, men, and bilateral, staging, and baseline samples. Only 4% of BMB and 2% of BMB/BMA samples were deemed inadequate for diagnosis. BM for plasma cell dyscrasias, nonphysician operators, and ancillary studies usage increased, while bilateral sampling decreased over the decade. BM-related quality assurance programs are infrequent. CONCLUSIONS: CL is shorter than recommended and varies with patient age and sex, clinical circumstances, and center experience. While pathologists render diagnoses on most cases irrespective of CL, BMB yield improvement is desirable.

Preleukemic phase of chronic myelogenous leukemia: morphologic and immunohistochemical characterization of 7 cases.

Patients with chronic myelogenous leukemia (CML) present typically with an elevated white blood cell count (WBC) and cytogenetic or molecular genetic evidence of t(9;22)/BCR-ABL1 fusion gene. Rarely, CML patients may present with a normal or mildly elevated WBC and are asymptomatic, and we describe 7 patients in this study. The WBC in these patients ranged from 3.6 to 14.3 K/mm(3) with 50% to 73% granulocytes and 0% blasts. In all patients, t(9;22)(q34;q11.2) was detected by conventional cytogenetics, and BCR-ABL1 fusion was shown, supporting the diagnosis of preleukemic CML (pre-CML). We compared these patients with a group of 5 cases of CML in chronic phase (CML-CP) and 5 bone marrow specimens with a leukemoid reaction (n=5). Reticulin, CD34, and CD61 immunostains were performed on all bone marrow biopsy specimens. Peripheral blood absolute basophilia (≥200/mm(3)) was noted in only 4 of 7 pre-CML cases, whereas it was present in all CML-CP cases and absent in leukemoid reaction cases. The mean ±SD of microvascular density of pre-CML cases (10.0 ± 4.3 vessels/200× field) was twice that of leukemoid reaction cases (5.0 ± 1.0) (P=.02; Student t test) but similar to that of CML-CP cases (12.5 ± 3.6). Microvessels in pre-CML, highlighted by CD34, were tortuous with abnormal branching, although to a lesser extent than those found in CML-CP. Microvessels in leukemoid reaction were generally straight. The percentage of small, hypolobated megakaryocytes, highlighted by CD61 in pre-CML, was 40%, 3 times that found in leukemoid reaction cases (13%) but less than that of CML-CP cases (86%). We conclude that pre-CML should be suspected in patients with a normal to mildly elevated WBC and absolute basophilia. Bone marrow examination can usually distinguish pre-CML from a leukemoid reaction based on the percentage of small, hypolobated megakaryocytes; microvascular density; and morphologic features.

Angiosarcoma of small bowel presenting with obstruction: novel observations on a rare diagnostic entity with unique clinical presentation.

We present a case of angiosarcoma in small bowel, presenting with partial small bowel obstruction in a 79-year-old man with no history of radiation, chemotherapy, toxin exposure, or previous operative intervention. Angiosarcoma of small bowel is a rare entity which may present with nausea, abdominal pain, recurrent bleeding, and usually a history of prior radiation or exposure to specific toxins (polyvinyl chloride). Angiosarcoma of small bowel tends to spread rapidly and has a poor prognosis. We review the surgical and oncologic challenges. We report unique macroscopic findings of raised hyperemic margins, which are suggestive of a vasogenic lesion and the histologic feature of a partially retiform pattern with dense basement membrane material in an otherwise poorly differentiated lesion.