Cryptogenic Pontine Abscess Treated With Stereotactic Aspiration: A Case Report.

Brainstem abscesses are localized collections of pus or infected material within the brainstem, which can cause inflammation, tissue damage, and compression of adjacent structures. This can lead to a variety of symptoms, including headache, fever, and focal neurological deficits, among many others. Brainstem abscesses are potentially life-threatening and considered to be rare, and pontine abscesses are even rarer. Both are often caused by the spread of infection from nearby structures like the middle ear, sinuses, and mastoid air cells, but they can also result from distant infectious sites that have spread to the bloodstream. Ambiguous clinical presentation can delay appropriate care and lead to poorer outcomes. We present a rare case of pontine abscess in a 54-year-old male with both undetermined causal origins and unclear infectious signs, namely, the lack of fever, fatigue, and chills. We will discuss the etiologies, diagnosis, and treatment of cryptogenic brainstem lesions in this case report.

Local memory allocation recruits memory ensembles across brain regions.

Memories are thought to be stored in ensembles of neurons across multiple brain regions. However, whether and how these ensembles are coordinated at the time of learning remains largely unknown. Here, we combined CREB-mediated memory allocation with transsynaptic retrograde tracing to demonstrate that the allocation of aversive memories to a group of neurons in one brain region directly affects the allocation of interconnected neurons in upstream brain regions in a behavioral- and brain region-specific manner in mice. Our analysis suggests that this cross-regional recruitment of presynaptic neurons is initiated by downstream memory neurons through a retrograde mechanism. Together with statistical modeling, our results indicate that in addition to the anterograde flow of information between brain regions, the establishment of interconnected, brain-wide memory traces relies on a retrograde mechanism that coordinates memory ensembles at the time of learning.

Molecular Cytogenetic Characterization of a Structural Abnormal Chromosome 16 in a Patient with Acute Myeloid Leukemia Leading to Inversion Chromosome 16 with Concomitant 3'CBFB Deletion.

OBJECTIVES: Acute myeloid leukemia (AML) presents as a heterogeneous blood cancer characterized by the proliferation of immature myeloid cells. We present the case of an 18-year-old female with AML whose symptoms include marked leukocytosis, anemia, as well as thrombocytopenia with spontaneous cerebellar and intracerebral bleeds. The bone marrow biopsy is hypercellular and is expunged by sheets of blast cells with dispersed chromatin, prominent nucleoli, highly irregular nuclei, and moderate cytoplasm. Chromosome analysis reveals an abnormal karyotype with a derivative trisomy 8 and a derivative chromosome 16. The karyotype is described as 47,XX,+der(8)add(8)(q24.3),der(16) inv(16)(p13.1q22)del(16)(q22)[21]/46,XX[1]. DNA FISH analysis reveals abnormalities for RUNX1T1 (8q21.3) and CBFB (16q22) genes. These findings align with that of conventional cytogenetics. The National Comprehensive Cancer Network guidelines for AML state that CBFB gene rearrangements indicate that the patient falls under the favorable risk category. However, AML with core binding factor molecular aberrations is a heterogeneous group and thus the interaction with further cytogenetic abnormalities may result in further pathogenesis. Clinical correlation was suggested.

Applications and Advancements of CRISPR/Cas9 Technology: An Update.

OBJECTIVES: The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system is an RNA-guided DNA targeting platform widely known for its application in genome editing. Originally derived from the bacterial and archaebacterial defense mechanism against phage infection, it has since been studied and utilized for its potential as a genetic engineering tool and as a therapeutic agent. The Cas9 protein in its standard form induces double-stranded breaks (DSBs) in the target dsDNA sequence; however, modifications of the Cas9 protein have allowed for single-stranded breaks (SSBs) and even epigenetic modifications of gene expression. In comparison with previous methods including RNA interference, Zinc Finger Nucleases, and TAL Effector Nucleases, CRISPR is cheaper, more easily customized, and has a higher fidelity to its target site with fewer off-target effects. Consequently, CRISPR has become a central gene editing technique in a broad variety of research settings, with great potential for applications in human health. In this review, we offer an overview of CRISPR's mechanism of action and recent advancements in the application of CRISPR, as well as discuss literature pertinent to CRISPR applications to human health including many exciting prospective treatments for serious pathologies.

A t(9;11)(p22;q23) Within the Context of a Complex Karyotype is Associated with a Poor Prognosis in a 19-Year-Old Patient with AML.

OBJECTIVES: A 19-year-old male with a history of irritable bowel syndrome presented with progressive fatigue, periorbital petechiae, and abdominal pain for 2-3 weeks. The peripheral blood smear showed leukocytosis and circulating blasts. Elevated PT, PTT, and FDP with normal fibrinogen were found in the DIC panel workup. Abdominal CT suggested splenomegaly. A bone marrow biopsy revealed sheets of monotonous agranular monoblasts nearly completely replaced the hematopoietic elements. Chromosome analysis depicted an abnormal male karyotype with a t(9;11)(p22;q23) in all metaphase cells examined. Four cells showed, in addition, two 8q isochromosomes. FISH analysis was utilized with the MYC (8q24.21) probe from Abbott and the KMT2A (11q23), those of which showed gain on MYC and evidence of KMT2A. These findings correlate with the concurrent conventional cytogenetic findings and were described as nuc ish(MYCx4~9)[182/200],(KMT2Ax2)(5'KMT2A sep 3'KMT2Ax1)[181/200]. Complex karyotypes are associated with poor prognosis. Although only a few pediatric cases exist in the literature, the presence of additional abnormalities put this finding as a poor prognostic marker in AML. Correlation with other clinical data was indicated.

FLT3 Gene Involvement in B-cell Acute Lymphoblastic Leukemia (B-ALL).

OBJECTIVES: The FMS-like tyrosine kinase 3 gene (FLT3) is a receptor tyrosine kinase expressed in early hematopoietic progenitors that play an important role in hematopoietic development. The signaling pathways that are stimulated by the FLT3 protein manage several crucial cellular processes including division, growth, and survival of cells, specifically of hematopoietic progenitor cells. Activating mutations of this gene have been highly discussed in myeloid malignancies, including myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). However, FLT3 mutations are also observed in around 5% of acute lymphoblastic leukemia (ALL) patients. These mutations were usually found to be one of the four types: internal tandem duplications, tyrosine kinase domain mutations, juxtamembrane insertion and deletion, and juxtamembrane point mutation. The presence of FLT3 mutations in pediatric B-ALL patient populations tend to be associated with relapse and poor prognosis. These mutations are also correlated with poor prognosis in adult B-ALL patients. Due to the rarity of FLT3 mutations in B-ALL patients, there have been many challenges in attempts to understand their role in pathogenesis. In this review, we will discuss the most recent literature and trends associated with FLT3 mutations in B-ALL patients in order to elucidate their cytogenetic, molecular, and clinical implications.

FISH is Still an Excellent Tool to Monitor High-Grade Lymphomas.

OBJECTIVES: A 61-year-old male patient whose core needle biopsies of tissue involved a malignant lymphoid infiltrate composed of intermediate to large cells positive for CD20, PAX5, CD10, BCL6, BCL2, and cMYC, and negative for MUM1. Mitotic activity was brisk with a correspondingly high index of proliferation by Ki67 (~95%) and the patient was diagnosed with a diffuse large B-cell lymphoma, germinal center phenotype. DNA FISH analysis was performed on the paraffin embedded tissue from the right external iliac lymph node using the LSI BCL6 (3q27) and MYC (8q24) dual color break apart probes from Cytocell and the LSI BCL2 (18q21) dual color break apart probe from Abbott. We found rearrangements of BCL6 in 95% of the cells examined, MYC rearrangements in 77% of the cells and BCL2 rearrangements in 95% of the nuclei. These findings allowed us to classify this case as a triple-hit lymphoma now called "high-grade B-cell lymphomas" with MYC, BCL2, and/or BCL6 rearrangements.

A t(8;14)(q24.1;q32) in Plasma Cell Myeloma: A Case Report and Literature Review.

OBJECTIVES: We report a 74-year-old male whose bone marrow morphology, flow cytometry, MRI and serum electrophoresis showed evidence of plasma cell myeloma. Chromosome analysis of the bone marrow showed an abnormal karyotype, described as 51~53,XY,+3,+5,t(8;14)(q24 .1;q32),+9,+11,+15,+19,+21[cp6]/46,XY[14]. The t(8;14)(q24.1;q32) is mainly seen in Burkitt lymphoma but it can also be seen in plasma cell myeloma usually with the context of a complex karyotype. Based on the Mitelman database the involvement of C-MYC is usually seen in late tumor progression in plasma cell myeloma as a secondary rearrangement, usually during clonal evolution and divergence and is associated with a significantly decreased survival. Our case pinpoints the involvement of MYC abnormalities in plasma cell myeloma as well as the importance of cytogenetics as a tool to manage and monitor plasma cell myeloma cases.

A Case of t(1;6)(p12;p11.1), Deletion 5q, and Ring 11 in a Patient with Myelodysplastic Syndrome with Excess Blasts Type 1.

OBJECTIVES: We present the case of a 56-year-old male with myelodysplastic syndrome (MDS) whose bone marrow immunophenotype showed lower positivity for CD45 and positivity for CD34; 8.66% of this population also expressed partial positives for MPO, CD16, CD117, CD36, CD33, and CD71, as well as positives for CD13, HLA-DR, and CD11b. No alterations in the pattern of maturation were seen in CD13 vs CD16 and CD13 vs CD11b. An analysis of a population of mature lymphocytes revealed CD45 high CD3+ in 87.5% of cells, CD45 high CD19+ in 7.6% of cells, and 4.9% NK cells. These results are consistent with a myelodysplastic syndrome with an excess of blasts type 1. Chromosome analysis of the bone marrow revealed an abnormal karyotype with a t(1;6)(p12;p11.1) as well as deletion 5q and a ring 11 in 12 of the 20 metaphase cells examined. The t(1;6)(p12;p11.1) has not been reported in association with any particular hematological malignancy and provides further insight into the range of cytogenetic abnormalities in MDS.

T-Cell Acute Lymphoblastic Leukemia: A Cytogenomic Update.

OBJECTIVES: T-cell acute lymphoblastic leukemia (T-ALL) is a pervasive hematologic malignancy that arises from developmental and genetic abnormalities manifested in lymphoblasts belonging to the T-cell lineage. Responsible for 10-15% of pediatric acute lymphoblastic leukemia (ALL) and 25% of adult ALL patients, T-ALL is characterized not only by cytomorphic features, but also by the aberrant expression of specific genes critical to T-cell development. Such changes in the genome ultimately result in mutational and developmental cascades that alter the chromosomal constitution, the process of which are used to organize T-ALL cases into different subgroups according to specific gene expression signatures. Clinically, comprehensive categorizations are important in risk stratification, assessment, and treatment protocols. Notable genetic subgroups include that of TAL, TLX1, TLX3, HOXA, MYB, ETP and NKX2. Current research also recognizes phenotypic and immunologic categories, such as ALK-positive ALCL, ALK-negative ALCL, BIA ALCL, AITL, and PTCL, NOS, which has revolutionized our understanding of T-cell lymphoma. Furthermore, it has been suggested that most T-ALL patients present with abnormal NOTCH1 genes in addition to mutations involving the JAK-STAT signaling pathway. These abnormalities are associated with the regulatory malfunction of T-cell development as well as that of their respective tumor suppressors and oncogenes. While recent studies have revealed characteristic defects in T-ALL, the interactions between oncogenes and their tumor suppressors with leukemia development are not well known as the signaling pathways involved behind each genetic lesion have yet to be fully explored. Studies involving FISH, RT-PCR, aCGH, and NGS offer novel perspectives to potentially learn more about the pathogenesis and cytogenetics of T-ALL, a field that demands further attention and research.

Transient Myeloproliferative Disorder: A Cytogenomic Update.

OBJECTIVES: Transient myeloproliferative disorder (TMD), now more commonly known as transient abnormal myelopoiesis (TAM), is a condition closely associated with Down syndrome. Ninety-five percent of Down syndrome cases occur as a result of chromosomal nondisjunction and are rarely due to mosaicism or translocation. TMD is found exclusively in neonates and is most commonly characterized by trisomy 21, somatic GATA1 mutation, and the increased presence of megakaryoblasts. TMD often does not manifest clinically, but patients may show hepatomegaly, splenomegaly and other symptoms. While TMD is almost always present with trisomy 21, there are not many other cytogenetic abnormalities associated with TMD, with a few rare cases such as monosomy 7 and trisomy 8. Recent studies have suggested liver hematopoietic progenitor cells as the candidate for TMD origin. Furthermore, GATA1 mutations associated with TMD are found to encode for a stop codon in the N-terminal activation region of gene sequences. It has been shown that those mutations can cause overproliferation of megakaryocytes, which can cooperate with Down syndrome cells, which have trisomy 21, in the progression of TMD into acute megakaryoblastic leukemia (AMKL). Since GATA1 mutations are present in all cases of myeloid leukemia of Down Syndrome, monitoring GATA1 in patients with trisomy 21 may assist with earlier diagnosis of TMD. Another likely cause of TMD is the amplification of the RUNX1 transcription factor gene located on chromosome 21. It has been shown that RUNX1 is associated with leukemias of myeloid lineage. While most cases of TMD will spontaneously resolve, some will evolve into acute myeloid leukemia (AML). In this review, we will discuss the cytogenetic, molecular genetics and clinical aspects of TMD.