College of American Pathologists/American College of Medical Genetics proficiency testing for constitutional cytogenomic microarray analysis.

PURPOSE: To evaluate the feasibility of administering a newly established proficiency test offered through the College of American Pathologists and the American College of Medical Genetics for genomic copy number assessment by microarray analysis, and to determine the reproducibility and concordance among laboratory results from this test. METHODS: Surveys were designed through the Cytogenetic Resource Committee of the two colleges to assess the ability of testing laboratories to process DNA samples provided and interpret results. Supplemental questions were asked with each Survey to determine laboratory practice trends. RESULTS: Twelve DNA specimens, representing 2 pilot and 10 Survey challenges, were distributed to as many as 74 different laboratories, yielding 493 individual responses. The mean consensus for matching result interpretations was 95.7%. Responses to supplemental questions indicate that the number of laboratories offering this testing is increasing, methods for analysis and evaluation are becoming standardized, and array platforms used are increasing in probe density. CONCLUSION: The College of American Pathologists/American College of Medical Genetics proficiency testing program for copy number assessment by cytogenomic microarray is a successful and efficient mechanism for assessing interlaboratory reproducibility. This will provide laboratories the opportunity to evaluate their performance and assure overall accuracy of patient results. The high level of concordance in laboratory responses across all testing platforms by multiple facilities highlights the robustness of this technology.

Conventional Cytogenetic Analysis of Hematologic Neoplasms: A 20-Year Review of Proficiency Test Results From the College of American Pathologists/American College of Medical Genetics and Genomics Cytogenetics Committee.

CONTEXT.­: One goal of the joint College of American Pathologists/American College of Medical Genetics and Genomics Cytogenetics Committee is to ensure the accurate detection and description of chromosomal abnormalities in both constitutional and neoplastic specimens, including hematologic neoplasms. OBJECTIVE.­: To report a 20-year performance summary (1999-2018) of conventional chromosome challenges focusing on hematologic neoplasms. DESIGN.­: A retrospective review was performed from 1999 through 2018 to identify karyotype challenges specifically addressing hematologic neoplasms. The overall performance of participants was examined to identify potential recurring errors of clinical significance. RESULTS.­: Of 288 total conventional chromosome challenges from 1999-2018, 87 (30.2%) were presented in the context of a hematologic neoplasm, based on the provided clinical history, specimen type, and/or chromosomal abnormalities. For these 87 hematologic neoplasm challenges, 91 individual cases were provided and graded on the basis of abnormality recognition and karyotype nomenclature (ISCN, International System for Human Cytogenomic [previously Cytogenetic] Nomenclature). Of the 91 cases, 89 (97.8%) and 87 (95.6%) exceeded the required 80% consensus for grading of abnormality recognition and correct karyotype nomenclature, respectively. The 2 cases (2 of 91; 2.2%) that failed to meet the 80% consensus for abnormality recognition had complex karyotypes. The 4 cases (4 of 91; 4.4%) that failed to meet the 80% consensus for correct karyotype nomenclature were the result of incorrect abnormality recognition (2 cases), missing brackets in the karyotype (1 case), and incorrect breakpoint designation (1 case). CONCLUSIONS.­: This 20-year review demonstrates clinical cytogenetics laboratories have been and continue to be highly proficient in the detection and description of chromosomal abnormalities associated with hematologic neoplasms.

Relapsed Acute Promyelocytic Leukemia Lacks "Classic" Leukemic Promyelocyte Morphology and Can Create Diagnostic Challenges.

OBJECTIVES: Although current therapies for acute promyelocytic leukemia (APL), such as all- trans retinoic acid and arsenic trioxide, usually result in remission, some patients relapse. Early recognition of relapse is critical for prompt intervention. In this study, we systematically reviewed morphologic, immunophenotypic, and cytogenetic findings in paired diagnostic and relapsed APL cases and describe and quantify the changes in blast morphology at relapse. METHODS: By electronic database search, we identified eight paired diagnostic and relapsed APL cases for which peripheral blood or bone marrow smears were available for review. For two cases, diagnostic material was available for relapse after hematopoietic cell transplantation. RESULTS: Neoplastic hypergranular or microgranular promyelocytes with indented or bivalve nuclei predominated at diagnosis in all patients. Most patients had undifferentiated blasts at relapse and/or hypergranular blast equivalents with round to oval nuclei. Classic acute promyelocytic leukemia cells with bivalve nuclei and bundles of cytoplasmic Auer rods were easily identifiable in fewer than half of cases at diagnosis and rare to absent in all relapsed cases. CONCLUSIONS: Morphologic features of relapsed APL overlap with other types of acute myeloid leukemia, creating diagnostic challenges, especially if no history is available when relapsing patients seek treatment for care.

Aplastic anemia and monosomy 7-associated dysmegakaryocytopoiesis.

Aplastic anemia (AA) is marrow failure due to an inadequate number of hematopoietic cells in the marrow. Prior reports have described a more aggressive clinical course in aplastic anemia with monosomy 7. We report 3 pediatric cases of AA with normal cytogenetics followed by acquisition of monosomy 7. Bone marrow biopsies were initially diagnostic of AA but later showed monosomy 7 and an increased number of megakaryocytes with small hypolobated nuclei. Immunohistochemical stains for CD61 highlighted the marked dysmegakaryocytopoiesis. The marrow blast percentage was increased in only 1 patient with 4.6% blasts. The 3 patients underwent bone marrow transplantation, and each has remained disease free for 7 to 18 months after transplantation. Pediatric patients with AA and normal cytogenetics may develop monosomy 7 with a myelodysplastic syndrome, unclassified. Patients with AA and monosomy 7 should be evaluated for dysmegakaryocytopoiesis.

Diagnostic significance of detecting dysgranulopoiesis in chronic myeloid leukemia.

We examined whether the detection of dysgranulopoiesis in blood or bone marrow would predict chronic myeloid leukemia (CML) in transformation in 31 cases that fulfilled World Health Organization criteria for disease transformation, including 14 in accelerated phase (AP), 10 in myeloid blast crisis (MBC), and 7 in lymphoid blast crisis (LBC). Dysgranulopoiesis was detected in 7 cases, 6 in AP and 1 in MBC, but not in LBC or chronic phase cases. In 3 AP cases, dysgranulopoiesis was identified 2 to 5 months before the morphologic diagnosis of transformation. Two AP cases showed no dysgranulopoiesis in previous blood or marrow smears. For 2 cases (1 AP and 1 MBC), no previous blood or marrow specimens were available. Cytogenetic information was available for 6 of 7 cases with and 22 of 24 cases without dysgranulopoiesis. All cases with dysgranulopoiesis had secondary chromosome abnormalities in addition to t(9;22). In 5 (83%) of 6 cases with dysgranulopoiesis, the secondary chromosome abnormalities included abnormalities of 17p. In contrast, none of the 22 cases of CML in AP or BC but without dysgranulopoiesis showed 17p abnormalities (P = .001). Our findings demonstrated that dysgranulopoiesis was associated strongly with chromosome 17p abnormalities and may indicate the onset of or impending disease transformation.

Early diagnosis of intravascular large B-cell lymphoma: clues from routine blood smear morphologic findings.

Intravascular large B-cell lymphoma (IVLBCL) is a mature B-cell neoplasm characterized by malignant lymphoid cells within the lumina of blood vessels and capillaries. Given its varied and nonspecific clinical manifestation, this aggressive disease is often not diagnosed until an advanced clinical stage or even at autopsy. This case highlights a patient presenting with autoimmune hemolytic anemia (AIHA) and fevers. Atypical circulating cells on a screening peripheral smear lead to flow cytometric studies highlighting an increase in large, light chain restricted CD20 positive cells. A diagnostic bone marrow biopsy was performed and trephine cores demonstrated predominantly intrasinusoidal lymphoma cells. In conjunction with additional immunophenotypic data, these studies strongly supported a diagnosis of IVLBCL. Judicious use of flow cytometry and morphology resulted in an early-stage diagnosis and likely contributed to the patient's current complete remission status following anti-CD20 therapy. Differential diagnoses for this presentation are discussed in light of serologic, immunophenotypic, histologic, and cytogenetic findings.

Follicular lymphoma transformed to "double-hit" B lymphoblastic lymphoma presenting in the peritoneal fluid.

Lymphomas showing both MYC/8q24 rearrangement and IGH@BCL2/t(14;18)(q32;q21), also referred to as "double-hit" or "dual-hit" lymphomas (DHL) are rare B-cell malignancies with a germinal center B-cell immunophenotype and heterogeneous cytologic and histologic features. Such lymphomas may arise de novo or through transformation of follicular lymphomas and are classified either as "B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma (BL)" (most commonly), DLBCL, or, rarely, as B-lymphoblastic lymphoma. We report a case of B-lymphobastic lymphoma arising through transformation of follicular lymphoma diagnosed on peritoneal fluid cytology, flow cytometry, and cytogenetic studies in a 53-year-old man who presented with abdominal pain, shortness of breath, night sweats, extensive lymphadenopathy, pleural effusion, and ascites. Cytologic examination of the ascitic fluid showed two distinct populations of neoplastic lymphoid cells, a predominant population of larger cells with fine powdery ("blastic") chromatin, visible to prominent nucleoli and occasional small cytoplasmic vacuoles and a less numerous population of smaller cells with centrocytic morphology. Flow cytometry also showed two distinct monotypic B-cell populations, both expressing CD10, and TdT-positivity was demonstrated immunohistochemically. Fluorescence in situ hybridization (FISH) demonstrated both MYC rearrangement and IGH/BCL2 gene fusion and cytogenetic analysis showed a complex karyotype including both t(14;18)(q32;q21) and t(8;22)(q24.1;q11.2). Since DHL pursue an aggressive clinical course, respond poorly to therapy, and have a poor outcome, it is important to suspect the diagnosis when encountering neoplastic lymphoid cells that are difficult to classify in effusion cytology specimens and to order the appropriate immunophenotyping and cytogenetic studies.

Ewing sarcoma and primitive neuroectodermal tumor of the esophagus: report of a case and review of literature.

This study presents a case of Ewing sarcoma and primitive neuroectodermal tumor arising in the esophagus of a 44-year-old woman who presented with progressive dysphagia. Imaging studies demonstrated a polypoid lesion in the esophagus. The tumor was characterized by corded and pseudopapillary architecture, cytologic monotony, and low proliferative activity. Immunohistochemical stains were positive for CD99, neuron-specific enolase, vimentin, cyclin D1, p53, and FLI1 gene product. Fluorescence in situ hybridization demonstrated a 22q12 translocation, associated with primitive neuroectodermal tumor in the tumor cells, whereas reverse transcription polymerase chain reaction conformed expression of Ewing sarcoma/FLI1 fusion transcript in the patient's bone marrow aspirate. Although this is a rare site for this type of tumor to occur, primitive neuroectodermal tumor should be considered in the differential diagnosis of mesenchymal tumors of the esophagus. Genetic analysis is crucial to establish the diagnosis and can be successfully performed on formalin-fixed, paraffin-embedded material and hematopoietic tissue.