C-MYC Amplification in Chronic Lymphocytic Leukemia: A Case Report and Review of the Literature.

OBJECTIVES: Chronic lymphocytic leukemia (CLL) is among the most common forms of leukemia diagnosed in the United States. It is associated with a variety of clinically significant genetic abnormalities, including cytogenetic abnormalities that are assessed routinely. Herein, we present a case of CLL for which molecular cytogenetic analysis revealed concomitant deletion of TP53 (17p13.1) in 87% of cells analyzed and amplification (3-20 signals) of C-MYC (8q24.1) in 47% of cells analyzed. Although rearrangements involving C-MYC are common in CLL, amplification is a rarer phenomenon that has not been investigated as thoroughly and may be overlooked during routine analysis. We review this case in the context of available literature on the plethora of genetic abnormalities involving C-MYC in CLL and their relevance to the pathogenesis of the disease. All in all, this case highlights the role of comprehensive, multidisciplinary genetic testing in the management of CLL.

Cytogenetic Findings in a Case of Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN).

OBJECTIVES: Blastic plasmacytoid dendritic cell neoplasm (BPDCN), previously known as natural killer (NK) cell leukemia/lymphoma, is categorized by the World Health Organization as a sole entity. Most often, BPDCN presents with features of both lymphoma and leukemia. The average age at diagnosis is 60 to 70 years and there are more men than women who are diagnosed with BPDCN. Herein we report a 67-year-old female with a recent peripheral blood morphology revealing a hematopoietic leukemia process. Flow cytometry revealed an atypical cell population without B-cell or T-cell lineage expression. It was positive for CD45 and CD123 and negative for CD34. The peripheral blood showed blastic plasmacytoid dendritic cell neoplasm, macrocytic anemia and moderate thrombocytopenia. Chromosome analysis showed an abnormal clone with i(7)(q10) and monosomies of chromosomes 13 and 15. She underwent a bone marrow biopsy. Bone marrow and peripheral blood showed a blastic plasmacytoid dendritic cell neoplasm (BPDCN), hypercellular marrow (estimated 95%) with 90.4% blasts (aspirate smear).

A Plasma Cell Myeloma Case with an Abnormal Clone with a t(8;22)(q24.1;q11.2) Within the Context of a Hyperdiploid Complex Karyotype.

OBJECTIVES: We report here a 74-year-old male who was seen for recurrent respiratory infections, fatigue, and weight loss in November 2016. Bone marrow biopsy showed 90% involvement by plasma cell myeloma (PCM) [90% plasma cells, 40% cellular bone marrow]. Cytogenetic analysis of the bone marrow showed a complex karyotype described as: 53,Y,add(X)(p22.1),del(1)(p13p22),+3,add(3)(p13),add(4)(p12),+6,del(6)(q13q25),t(8;22)(q24.1;q11.2),+9,+11,+15,+15,+21[7]/46,XY[13]. This particular pattern with deletion 1p, deletion 6q, and a t(8;22)(q24;q11.2) within the context of a complex karyotype is seen in PCM. Fluorescence in situ hybridization analysis on the CDC138 sample was positive for additional copies of CEP7 (centromere 7), CEP9 (centromere 9), CEP11 (centromere 11), and CEP15 (centromere 15), suggesting polysomy. FISH using the MYC Vysis break apart probe showed evidence of MYC rearrangement similar to the breakpoint site seen in Burkitt lymphoma with t(8;22)(q24;q11). FISH using the IGL break apart probe (Cytocell, Cambridge, UK) showed evidence of a 22q11.2 rearrangement. The signal pattern showed a residual green signal (BCR), a green signal on the derivative 8, and a red signal on the derivative 22, suggesting that the breakpoint at 22q11.2 in this patient was located downstream of the BCR region of the IGL gene. The variant Burkitt-type translocation, t(8;22)(q24;q11), is a very rare abnormality in PCM, and this case is one of only several reported to date. In these patients, MYC abnormalities appear late in the course of the disease and have an immature phenotype. A review of several cases in the literature suggests that this translocation leads the MYC gene under direct regulation of the enhancer of the partner gene, and in our case, the IGL or a nearby gene, thereby causing high level transcription of MYC. This abnormality is usually present within a complex karyotype and is associated with tumor progression and a poor prognosis.

FLT3 mutations at diagnosis and relapse in acute myeloid leukemia: cytogenetic and pathologic correlations, including cuplike blast morphology.

CONTEXT: Acquired mutations in the fms-like tyrosine kinase 3 gene (FLT3) adversely impact relapse risk after chemotherapy in patients with acute myeloid leukemia (AML). The FLT3 mutation status may differ at diagnosis and relapse, suggesting a potential role in chemoresistance, yet few reports have addressed the cytogenetic and pathologic correlates of FLT3 mutations in relapsed AML. OBJECTIVES: To determine FLT3 mutations at diagnosis and relapse in a cohort of adult patients with chemoresistant AML and to correlate mutation status with multiple variables. DESIGN: We retrospectively determined FLT3 internal tandem duplication (FLT3/ITD) and FLT3 tyrosine kinase domain mutations in 50 diagnosis/relapse pairs. We correlated FLT3 status with karyotype, World Health Organization 2008 subtype, white blood cell count, biopsy cellularity, blast percentage, and the presence of invaginated ("cuplike") blast nuclei. RESULTS: In 11 of 50 patients (22%) the FLT3 mutation status differed at relapse and diagnosis, with a trend toward gain of FLT3/ITD (n = 7) and loss of FLT3 tyrosine kinase domain (n = 5) mutations. FLT3-mutated AMLs correlated with the World Health Organization 2008 subtype, AML, not otherwise specified, hyperproliferative features at diagnosis and relapse, and cytogenetic evolution. FLT3-wild type AMLs correlated with the subtype AML with myelodysplasia-related changes and frequently had adverse presentation karyotypes. Cuplike blast morphology was associated with FLT3/ITD+ status and with high mutation levels. Four of 7 patients with relapse-only FLT3/ITD mutations exhibited cuplike blasts at relapse after being noncuplike at diagnosis. CONCLUSIONS: In addition to well-known correlates in pretreatment specimens, FLT3 mutation status has pathologic and cytogenetic significance at relapse. A shift to cuplike blast morphology at relapse may herald emergence of a previously undetected FLT3/ITD mutation.

HER2 assessment by immunohistochemical analysis and fluorescence in situ hybridization: comparison of HercepTest and PathVysion commercial assays.

We determined HER2 protein overexpression by immunohistochemical analysis and HER2 gene amplification by fluorescence in situ hybridization (FISH) in 215 formalin-fixed, paraffin-embedded breast tumors. Pathologist concordance for immunohistochemical scoring, and HER2 status concordance, as determined by immunohistochemistry and FISH, were high for immunohistochemical 3+, 1+, and 0 tumors but poor for 2+ tumors. Consensus immunohistochemical scores correlated with absolute and chromosome 17 (CEPI 7)-corrected HER2 gene copy number Among HER2-nonamplified tumors, the immunohistochemical score and mean absolute chromosome 17 (CEP17) copy number were weakly correlated. Seventeen tumors were HER2-amplified using absolute HER2 gene criteria but nonamplified when corrected for chromosome 17 polysomy (8 of these were immunohistochemical 2+). Assessment of benign epithelium within the immunohistochemical slides revealed either no staining or basolateral membrane staining, suggesting normal HER2 protein expression. Twenty tumors showing similar basolateral HER2 immunostaining were all low-moderate grade, tubule-forming, and HER2-nonamplified (17) or borderline amplified (3). Additional studies relating changes in HER2 gene content due to amplification or chromosome 17 polysomy and HER2 protein expression may be helpful to pathologists who interpret HER2 immnuohistochemical slides. Breast tumors scored at 2+ should be analyzed by FISH, preferably using a dual-probe FISH assay capable of distinguishing HER2 gene amplification from chromosome 17 polysomy.