ZMIZ1::ABL1 Fusion: An Uncommon Molecular Event With Clinical Implications in Pediatric Cancer.

CONTEXT.­: Pediatric B-cell acute lymphoblastic leukemia is genetically and phenotypically heterogeneous, with a genetic landscape including chromosomal translocations that disrupt ABL proto-oncogene 1, non-receptor tyrosine kinase (ABL1). OBJECTIVE.­: To characterize an uncommon chromosomal translocation in acute leukemia. DESIGN.­: Genetic testing, including karyotype and fluorescence in situ hybridization (FISH) analysis, was used to determine the underlying genetic aberration driving the disorder and to guide disease classification and risk stratification. More-detailed testing using RNA sequencing was performed, based on the results from these assays. Three-dimensional molecular modeling was used to visualize the impact of aberrant fused transcripts identified by transcriptome profiling. RESULTS.­: Karyotype analysis of the bone marrow demonstrated a complex karyotype with, most notably, a t(9;10)(q34.1;q22) translocation. ABL1 break-apart probe FISH findings supported ABL1 disruption. Bone marrow transcriptome analysis revealed mutant ZMIZ1::ABL1 (ZMIZ1, zinc finger MIZ-type containing 1) fusion transcripts as a consequence of t(9;10)(q34.1;q22). Three-dimensional modeling of the mutant ZMIZ1::ABL1 fusion protein confirmed an altered ABL1 protein structure compared to that of the wild type, suggesting a constitutively active conformation. CONCLUSIONS.­: The t(9;10) translocation resulting in ZMIZ1::ABL1 fusion transcripts is an uncommon form of BCR::ABL1-like (BCR, BCR activator of RhoGEF and GTPase) acute lymphoblastic leukemia. Although the karyotype was complex, identifying the t(9;10)(q34.1;q22) translocation, ABL1 disruption, and ZMIZ1::ABL1 transcript enabled effective ABL1-targeted treatment. Our data support the use of tyrosine kinase inhibitors to treat ZMIZ1::ABL1-derived B-cell acute lymphoblastic leukemia.

Improvement of diagnosis in children with Burkitt lymphoma in Kenya: feasibility study for the implementation of fluorescence in situ hybridisation testing for MYC and the MYC/IGH translocation.

Background: Indiana University (IU) initiated fluorescence in situ hybridisation (FISH) methodology for Burkitt Lymphoma (BL) to advance the accuracy and speed of diagnosis in the AMPATH Reference Laboratory at Moi Teaching and Referral Hospital (MTRH) in Eldoret, Kenya. Standard diagnostic testing for BL at MTRH includes morphology of the biopsy specimen or aspirate and limited immunohistochemistry panels. Methods: Tumour specimens from 19 children enrolled from 2016 to 2018 in a prospective study to improve the diagnosis and staging of children with suspected BL were evaluated. Touch preps from biopsy specimens or smears from fine needle aspiration were collected, stained with Giemsa and/or H&E and reviewed by pathologists to render a provisional diagnosis. Unstained slides were stored and later processed for FISH. Duplicate slides were split between two laboratories for analysis. Flow cytometry results were available for all specimens. Results from the newly established FISH laboratory in Eldoret, Kenya were cross-validated in Indianapolis, Indiana. Results: Concordance studies found 18 of 19 (95%) of specimens studied yielded analysable FISH results for one or both probe sets (MYC and MYC/IGH) in both locations. There was 94% (17/18) concordance of results between the two FISH laboratories. FISH results were 100% concordant for the 16 specimens with a histopathological diagnosis of BL and two of three non-BL cases (one case no result in IU FISH lab). FISH was similarly concordant with flow cytometry for specimens with positive flow results with the exception of a nasopharyngeal tumour with positive flow results for CD10 and CD20 but was negative by FISH. The modal turn-around time for FISH testing on retrospective study specimens performed in Kenya ranged between 24 and 72 hours. Conclusion: FISH testing was established, and a pilot study performed, to assess the feasibility of FISH as a diagnostic tool for the determination of BL in a Kenyan paediatric population. This study supports FISH in limited resource settings to improve the accuracy and speed of diagnosis of BL in Africa.

Signet-ring cell lymphoma: clinicopathologic, immunohistochemical, and fluorescence in situ hybridization studies of 7 cases.

CONTEXT: Signet-ring cell lymphoma (SRCL) is a rare morphologic variant of non-Hodgkin lymphoma. Although it was initially reported as a rare morphologic variant of follicular lymphoma (FL), SRCL has to date been described in most types of non-Hodgkin lymphoma, mostly as single-case reports. OBJECTIVE: To study SRCL systematically by immunohistochemical stains and fluorescent in situ hybridization analyses. DESIGN: Seven SRCL cases were stained for CD3, CD5, CD20, PAX-5, CD10, CD21, CD23, cyclin D1, BCL2, BCL6, Ki-67, and MUM-1, and were analyzed by fluorescent in situ hybridization for BCL2, BCL6, MYC, and MALT1 rearrangements. Clinical information and patient outcome were reviewed in all patients. RESULTS: The patients were 3 women and 3 men, ranging in age from 31 to 75 years (average 60.3 years). The lesions involved lymph nodes, tonsil, parotid gland, soft tissue, and breast. There were 4 FLs, 1 diffuse large B-cell lymphoma (DLBCL), 1 DLBCL with FL, and 1 DLBCL with marginal zone lymphoma. All cases had typical signet-ring cell morphology. They were positive for CD20 and BCL-2, and had low-to-intermediate Ki-67 proliferation index (10%-40%) except in the parotid DLBCL with FL (70%). BCL-6 was detected in all but 1 FL (6/7). Fluorescent in situ hybridization detected IGH/BCL2 translocation in 1 FL, increased BCL6 copy number in another FL, BCL6 rearrangement, and increased copy number of MYC and MALT1 in the DLBCL with marginal zone lymphoma. CONCLUSIONS: The FL with signet-ring cell morphology (1/5) tends to lack IGH/BCL2 translocation, and an extended immunohistochemical study is recommended for correct diagnosis and classification of SRCL.

Luminal subtypes predict improved survival following central nervous system metastasis in patients with surgically managed metastatic breast carcinoma.

CONTEXT: Metastatic breast cancer to the central nervous system (CNS) is second only to lung cancer metastasis to the CNS in frequency. Patients with triple-negative primary breast cancer and those with human epidermal growth factor receptor 2 (HER2)-positive primary breast cancer are at an increased risk for metastasis. Very little is known about predictive or prognostic variables once patients develop CNS metastases. Currently, therapeutic options are limited, with surgery generally offered primarily to those with solitary lesions. OBJECTIVES: To determine the influence of molecular subtypes of metastatic breast cancer on survival from the time of CNS metastasis and to aid in the prognostic stratification of these patients. DESIGN: We identified 59 cases of metastatic breast cancer to the CNS and analyzed them for various demographic and clinicopathologic parameters. Tumors were categorized into molecular subtypes using immunohistochemical methods: luminal A [estrogen receptor (ER⁺)/Ki67low], luminal B (ER⁺/Ki67 high), intrinsic HER2 (ER⁻/HER2⁺), and triple-negative. Survival after CNS metastasis for each group was plotted using a Kaplan-Meier curve, and multivariate analysis was performed. RESULTS: Patients with metastases from luminal tumors had a statistically significant survival advantage when compared with those of the triple-negative phenotype. Importantly, survival among patients with luminal A and luminal B tumors was not significantly different. Similarly, patient's age, histologic grade, and number of lesions did not contribute to determining outcomes. CONCLUSIONS: Estrogen receptor positivity (ie, luminal phenotype) of tumors appears to determine outcomes after development of metastases. In contrast, proliferation rate had little or no effect on the long-term survival. Understanding the biology of metastases can help stratify patients into prognostically meaningful categories and tailor treatment regimens for individual patients.

Fluorescence in situ hybridization (FISH) as an aid for the diagnosis of graft-versus-host disease in two multivisceral organ transplant patients.

We herein describe 2 cases of adult multivisceral transplant patients who developed graft-versus-host disease manifesting predominantly as lichenoid skin papules and plaques. The diagnosis was supported by histopathology but ultimately corroborated by the utilization of the fluorescence in situ hybridization (FISH) technique using X and Y chromosome probes on unstained biopsy slides. In both cases, FISH revealed a high percentage of donor-derived cells as part of the inflammatory infiltrate in the skin biopsy. This report adds to the previous publications showing the utility of FISH in corroborating the diagnosis of graft-versus-host disease in transplant patients with unmatched sex donor.

Glioblastoma occurring at the site of a previous medulloblastoma following a 5-year remission period.

We describe a case of a 14-year-old boy who developed a cerebellar and brainstem glioblastoma 5 years after treatment for a medulloblastoma. The patient first presented in 2003 with 9 months of vomiting and a 9-kg weight loss. A head MRI showed a heterogeneously enhancing posterior fossa mass with hydrocephalus. Gross total resection was performed and the tumor was consistent with a classic medulloblastoma. Postoperative chemotherapy and craniospinal radiation was administered. The patient remained tumor-free until 2008, at which time he presented with right-sided weakness and numbness, left eye pain, vomiting and weight loss. Imaging showed abnormalities within the posterior pons, medulla, inferior cerebellar peduncles, cerebellar hemispheres and cervicomedullary junction with expansion of the medulla and cervical spinal cord. Due to the location of the lesion, biopsy was felt to be too risky and was avoided. Despite receiving chemotherapy, his symptoms continued to worsen and he died 4 months later. Post mortem examination limited to the brain and spinal cord confirmed the radiographic extent of the tumor. Microscopic examination showed a highly cellular infiltrative glial neoplasm with extensive palisading necrosis. A diagnosis of glioblastoma was rendered. The question of whether the first and second tumors were related is of potential clinical and academic interest. The first tumor was synaptophysin-positive and GFAP-negative, consistent with medulloblastoma. The second tumor was synaptophysin-negative and focally GFAP-positive, consistent with glioblastoma. The glioblastoma displayed EGF receptor amplification, and interestingly, it also displayed MYCN amplification; both tumors showed low level PTEN deletion. The medulloblastoma displayed a signal pattern consistent with an isochromosome 17q, while the glioblastoma showed some cells with an isochromosome 17q signal pattern amid a background of cells with abundant chromosomal instability. The relationship between these two tumors, particularly with regard to various molecular events, is discussed.

Most primary central nervous system diffuse large B-cell lymphomas occurring in immunocompetent individuals belong to the nongerminal center subtype: a retrospective analysis of 31 cases.

Primary central nervous system lymphomas are rare neoplasms characterized by a dismal prognosis relative to other extranodal lymphomas. Approximately 98% of primary central nervous system lymphomas are of B-cell origin, and most belong to the diffuse large B-cell type. Recently, diffuse large B-cell lymphomas have been subcategorized into germinal center and nongerminal center types based on gene expression profiles and immunohistochemical expression of CD10, Bcl-6, and MUM1. Studies have shown that the overall survival rate of the germinal center group is better than that of the nongerminal center lymphomas. In this study, 31 cases of primary central nervous system lymphomas of the diffuse large B-cell type were retrieved, reviewed, and immunostained for CD10, Bcl-6, MUM1, and Ki-67. Subclassification was carried out as described earlier, where CD10 and/or Bcl-6 positivity and negativity for MUM1 were considered characteristic of germinal center subtype and the opposite expression of nongerminal center subtype. Furthermore, the proliferative activity was semiquantitatively assessed using percent positive cells staining with Ki-67. Of the 31 cases examined, 26 (84%) were found to belong to the nongerminal center type. The Ki-67 index in these 26 cases ranged from 30 to 90% (mean, 69%). Five cases were categorized as the germinal center subtype. They had an Ki-67 index between 70 and 90% (mean, 78%). Interestingly, none of our patients were known to be HIV positive. One patient had a 10-year history of orthotopic liver transplant. We also performed fluorescence in situ hybridization analysis on formalin-fixed material and found that 38% of the cases where tissue was available had abnormalities of MYC/IGH and/or IGH/BCL2. We conclude that most primary central nervous system diffuse large B-cell lymphomas are of the nongerminal center origin. Regardless of the germinal center status, all cases showed a high proliferative rate. A statistically significant difference in the overall survival between the two groups was not seen.

A case of de novo partial tetrasomy of distal 6p and review of the literature.

We report on a 3-year-old girl with bilateral eyelid colobomas, bulbous nose, blepharophimosis, blepharoptosis, sensorineural hearing loss, atrial septal defect, psychomotor retardation, and growth delay. Cytogenetic analysis showed additional material of unknown origin on the short arm of chromosome 8. Whole chromosome paint FISH identified the additional material to originate from chromosome 6. Subtelomeric metaphase FISH analysis detected a bright signal pattern for the 6p subtelomere probe on the derivative 8 as well as two short arm signals for the normal chromosomes 6. Interphase FISH with the 6p subtelomere probe demonstrated four 6p signals. Interestingly, metaphase FISH with a probe for the 8p subtelomere region demonstrated a signal for 8p just proximal to the translocated material. Comparative genomic hybridization studies confirmed tetrasomy of the 6p subtelomere region from 6p25.1 --> 6p25.3. Thus our patient represents the first reported case of "pure" partial tetrasomy 6p, meaning the tetrasomy was not associated with a significant deletion of chromosome arm 8p. We compare here this case with previously reported cases of partial trisomy 6p and the resulting phenotypes.