Cytogenetic characterization of Ewing tumors using fine needle aspiration samples. a 10-year experience and review of the literature

Follicular Dendritic Cell Sarcoma: Cytogenetics and pathological findings

Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm with a non-specific and insidious presentation further complicated by the difficult diagnostic and therapeutic assessment. It has a low to intermediate risk of recurrence and metastasis. Unlike other soft tissue sarcomas or histiocytic and dendritic cell neoplasms, cytogenetic studies are very limited in FDCS cases. Although no specific chromosomal marker has yet been established, complex aberrations and different ploidy types have been documented. We report the case of a 39-year-old woman with FDCS who presented to the Sultan Qaboos University Hospital in Muscat, Oman, in February 2013. Ultrastructural, immunophenotypical and histological findings are reported. In addition, karyotypic findings showed deletions of the chromosomes 1p, 3q, 6q, 7q, 8q and 11q. To the best of the authors' knowledge, these have not been reported previously in this tumour. Techniques such as spectral karyotyping may help to better characterise chromosomal abnormalities in this type of tumour.

A t(17;22)(q21;q12) with partial ETV4 deletion in a soft tissue Ewing sarcoma

Cytogenetic analysis of a lumbar soft tissue Ewing sarcoma (ES) in a 7-month-old female child showed a t(17;22)(q21;q12), a rare translocation leading to an EWSR1-ETV4 chimeric transcript. These findings were confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and fluorescence in situ hybridization (FISH) techniques. The breakpoints were characterized by direct sequencing of the chimeric fusion gene. Tumor genotyping using the Affymetrix Genome-Wide Human single nucleotide polymorphism (SNP) array 6.0 Genechip identified deletions of both chromosomal regions involved in the translocation, resulting in partial deletion of ETV4, but an uninvolved EWSR1 gene. The creation of a fusion between EWSR1 and an ETS family gene consecutive to a chromosomal translocation is characteristic of the Ewing family of tumors (EFT). This is the first report of a deletion involving the two breakpoints in an EWS-ETS translocation. To date, only two cases of t(17;22)(q21;q12) in Ewing sarcoma have been reported, with no associated deletion. Interestingly, both cases had also occurred in soft tissue tumors, which are less common than their bone-involving counterparts.

Detection of SYT and EWS gene rearrangements by dual-color break-apart CISH in liquid-based cytology samples of synovial sarcoma and Ewing sarcoma/primitive neuroectodermal tumor

To improve cytologic diagnostic accuracy for translocation-associated sarcomas, we explored dual-color break-apart (dc) chromogenic in situ hybridization (CISH) on liquid-based cytology (LBC) samples of 2 prototypic sarcomas: synovial sarcoma (SS) and Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET). LBC samples of 10 cases of SS and 9 cases of ES/PNET were subjected to dc-CISH using probes for the specifically rearranged genes in each tumor entity: SYT in SS and EWS in ES/PNET. Rearranged SYT was successfully detected in all SSs but not in any ES/PNETs. In contrast, EWS rearrangement was identified in all ES/PNETs but not in any SSs. These results were validated by dc-fluorescence in situ hybridization and reverse transcription-polymerase chain reaction. dc-CISH on LBC samples is a reliable modality to detect gene rearrangements in sarcomas. This system has a clear advantage over other methods, enabling simultaneous visualization of the genetic abnormality and well-preserved, nonoverlapping cytomorphologic features with clear background under bright-field microscope.

Abdominal undifferentiated small round cell tumor with unique translocation (X;19)(q13;q13.3)

We describe a male with a large abdominal mass, most likely originating from the liver, with capsule rupture and tumor dissemination into the abdominal cavity. Adherence of the tumor to the diaphragm and lower right colon also were noted. A comprehensive evaluation of the mass revealed no tumor-defining histopathologic, immunocytochemical, ultrastructural, cytogenetic, or translocation features. The malignant tumor was found to have a novel translocation (X;19)(q13;13.3), which has not been reported in small round cell tumors of childhood or adults. The final diagnosis rendered was an undifferentiated small round cell tumor of uncertain cell of origin.

Detection of chromosomal aberrations in renal tumors: a comparative study of conventional cytogenetics and virtual karyotyping with single-nucleotide polymorphism microarrays

CONTEXT

-Renal epithelial neoplasms have characteristic chromosomal imbalances, and we have shown previously that virtual karyotypes derived from single-nucleotide polymorphism microarrays can be performed on formalin-fixed, paraffin-embedded tissue.

OBJECTIVE

-To perform a direct comparison of virtual and conventional karyotypes to evaluate concordance of results.

DESIGN

-Twenty archival formalin-fixed, paraffin-embedded tumor samples with preexisting, conventional cytogenetic results were analyzed with Affymetrix 10K 2.0 or 250K Nsp single-nucleotide polymorphism microarrays.

RESULTS

-Nineteen samples yielded adequate virtual karyotypes for interpretation. Eight samples showed complete agreement between the 2 techniques, and 8 samples showed partial agreement. The disease-defining lesions (eg, loss of 3p for clear cell carcinoma) were identified in all 19 cases by virtual karyotypes and in 15 cases by conventional karyotypes. Virtual and conventional karyotypic findings were concordant in the identification of these disease-defining lesions in 86% (13 of 15) of cases. In 3 cases, virtual karyotypes identified lesions consistent with the morphologic diagnosis, whereas the conventional karyotypes were unsuccessful because of insufficient tumor representation or stromal overgrowth. Two cases with acquired uniparental disomy were identified by single-nucleotide polymorphism arrays, and 5 cases with translocations were identified by conventional karyotype.

CONCLUSIONS

-Our results show that both techniques are able to identify the characteristic chromosomal abnormality for renal tumor subtypes in most cases. Discrepancies can be explained by inherent limitations of each technique, inadequate tumor sampling, and tumor heterogeneity. We conclude that virtual karyotyping is a robust alternative to conventional cytogenetics for the evaluation of chromosomal anomalies in formalin-fixed, paraffin-embedded tissues from renal epithelial neoplasms.

Multiple chromosome abnormalities in the pleural fluid of a patient with recurrent Ewing sarcoma

The authors report a 5.5-year-old male patient with a right paraspinal tumor, diagnosed as metastatic Ewing sarcoma. The pleural fluid along with the bone marrow was sent to the authors' laboratory for karyotyping. Bone marrow cultures revealed a normal karyotype, whereas 48, XY, i(1)(q11), +10, t(11;22)(q24;q12) karyotype was found in the cells obtained from the pleural fluid cultures. Trisomy 1q is quite frequently observed in Ewing sarcoma patients, mostly as part of unbalanced translocations, along with the common t(11;22) translocation. This patient's findings were significant, as the complex karyotype in the pleural effusion cells was observed.

Cytologic diagnosis of Ewing sarcoma/peripheral neuroectodermal tumor with paired prospective molecular genetic analysis

BACKGROUND

Ewing sarcoma/peripheral neuroectodermal tumor (EWS/PNET), since its characterization immunophenotypically and cytogenetically, has emerged as one of most common sarcomas of childhood. Currently, it is recognized that EWS/PNET can occur in any number of extraosseous sites and is one of several distinctive tumor types with an EWS translocation. In the past, the pathologic diagnosis of EWS/PNET relied on an open biopsy with the application of various ancillary studies, ranging from periodic acid-Schiff stain to molecular testing, but the tumor increasingly is diagnosed on the basis of cytologic specimens alone.

METHODS

The authors report 3 cases of EWS/PNET in patients aged 11 years to 53 years. These 3 patients had tumors that involved the parotid gland, cervical soft tissue, and pelvis, and were diagnosed by cytologic evaluation of fine-needle aspiration (FNA) biopsy material alone. The FNA materials also were evaluated prospectively by fluorescence in situ hybridization and/or reverse transcriptase-polymerase chain reaction.

RESULTS

The results emphasized the diagnostic utility of FNA biopsy material for morphologic and molecular analysis without compromising conventional cytologic and immunocytochemical analysis, and that prospective molecular testing of FNA specimens has utility in routine practice although it is subject to many of the same limitations that impact molecular analysis when applied to conventional tissue biopsy specimens.

CONCLUSIONS

The current results demonstrated that molecular genetic techniques can provide clinically useful ancillary information for FNA specimens when cytologic features and/or immunophenotype are equivocal on the basis of limited sampling or secondary changes, such as hemorrhage and/or necrosis.

Trisomy 8 as the sole chromosomal aberration in acute myeloid leukemia and myelodysplastic syndromes

Trisomy 8 as the sole abnormality is the most common karyotypic finding in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), occurring in approximately 5% and 10% of the cytogenetically abnormal cases, respectively. However, despite the high frequency of +8, much remains to be elucidated as regards its epidemiology, etiology, clinical impact, association with other chromosomal abnormalities, cell of origin, and functional and pathogenetic consequences. Here, we summarize and review these various aspects of trisomy 8, focusing on AMLs and MDS harboring this abnormality as a single change.

Small Round Cell Tumors of Bone

Context.—Primary small round cell tumors of the bone are a heterogeneous group of malignant neoplasms presenting predominantly in children and adolescents. They include Ewing sarcoma/peripheral neuroectodermal tumor or Ewing family tumors, lymphoma, mesenchymal chondrosarcoma, and small cell osteosarcoma. Even though they share many morphological similarities, their unique biological and genetic characteristics have provided substantial insights into the pathology of these diverse neoplasms.

Objective.—To provide an overview of the clinical, radiologic, pathologic, and genetic characteristics of these tumors along with a pertinent review of the literature.

Data Sources.—A literature search using PubMed and Ovid MEDLINE was performed, and data were obtained from various articles pertaining to clinicopathologic, biological, and genetic findings in these tumors. Additionally, findings from rare cases have been included from author's subspecialty experience.

Conclusion.—The diagnosis of small round cell tumors can be made accurately by applying clinicopathologic criteria, as well as a panel of immunohistochemical and genetic studies in appropriate cases. Molecular genetic studies may provide further insight into the biology, histogenesis, and prognosis of these tumors.

The usefulness of cytogenetic analysis in fine needle aspirates for the histologic subtyping of sarcomas

Conventional cytogenetic analysis performed from open biopsy tissue samples may be a useful adjunct for the histologic subtyping of bone and soft tissue sarcomas. However, its diagnostic utility in fine needle aspiration biopsy (FNAB) specimens is unclear. We retrospectively reviewed 24 consecutive FNAB bone and soft tissue sarcoma specimens, procured from 1995 to 2003, in which aspirated material was obtained for cytogenetic analysis. The study sample included eight Ewing sarcomas, six synovial sarcomas, five rhabdomyosarcomas, two myxoid liposarcomas, and one each of myxoid chondrosarcoma, osteosarcoma, and atypical lipoma. Cytogenetic analysis confirmed the t(X;18) in all six synovial sarcomas and the t(11;22) in three Ewing sarcomas. The t(2;13) was strongly suggested in one alveolar rhabdomyosarcoma. For two of these cases (both of which were synovial sarcomas), cytogenetic analysis was necessary for definitive diagnosis. While the positive cytogenetic results were supportive in the remainder, all were initially and accurately subtyped based on cytomorphology and/or immunohistochemistry. Cytogenetic analysis was noncontributory (eg no growth) in 14 sarcoma cases, but excluding the case of atypical lipoma, this did not preclude the rendering of an accurate diagnosis. Cytogenetic analysis can be performed on FNAB specimens from bone and soft tissue sarcomas and may be a useful diagnostic aid in difficult cases. However, when cell block material is available for immunohistochemistry, the majority of such cases are successfully subtyped.

Cytogenetic characterization of Ewing tumors with high-ploidy

The formation of a high-ploidy is rare in Ewing tumor (ET) and is in contrast to some other childhood tumors such as neuroblastoma. In a series of 37 Ewing tumors analyzed by conventional cytogenetics, 4 of the 34 tumors with an abnormal clone (11.8%) demonstrated the presence of a high-ploidy clone, with a chromosome number that ranged from hypotriploid to pentaploid. All 4 contained a t(11;22)(q24;q12) and the karyotypes had further aberrations of the type that would be generally expected in ET. Numerical aberrations represented the majority of the karyotypic events identified and gain of chromosome 8 and loss of chromosomes 3, 10, 16, 19, and 22 occurred in at least 3 tumors. However, no single mechanism could be implicated to explain the karyotypic picture of the 4 cases. It is proposed that high-ploidy subgroups exist in ET and it would be potentially erroneous to group these and other cases together when determining their clinical implications.

Primary subcutaneous primitive neuroectodermal tumor with aggressive behavior and an unusual karyotype: case report

Primitive neuroectodermal tumor/Ewing sarcoma (PNET/ES) rarely occurs in the skin and subcutaneous tissues. We present a case of a 16-year-old girl with primary cutaneous and subcutaneous PNET/ES of the abdominal wall. Despite wide local excision and chemotherapy, she rapidly developed cranial bone and brain metastases, followed by lung and skeletal metastases, and died shortly thereafter. The recurrent tumor exhibited light microscopic features of a small, round, blue cell tumor with intracytoplasmic glycogen. Immunohistochemical analysis showed positivity for CD99, CD56, S100, and glial fibrillary acid protein, and ultrastructural features included cytoplasmic glycogen and focal complex interdigitating synaptic junction-like cytoplasmic folds. Cytogenetic analysis of the relapsed tumor showed a complex karyotype: 47,XX,i(1)(q10), der(4)t(4;19) (q33 approximately q35;q13.1), + 8,t(15;17)(q24;p11.2 approximately p12),der(19)t (19;20)(q13.1;p11.2),der(22)t(20;22)(q13;q13). Cytogenetic, interphase fluorescence in situ hybridization, and molecular genetic analyses failed to show t(11:22) (q24;q12) or abnormalities of chromosome region 22q12. The clinical behavior and atypical and complex cytogenetic abnormalities exhibited by the tumor in this patient are unusual and represent the most aggressive end of the clinical spectrum of cutaneous and subcutaneous PNET/ES.

Molecular genetics of pediatric soft tissue tumors: clinical application

The application of molecular genetics to pediatric soft tissue tumors has grown tremendously over the last decade. It has resulted in the identification of novel genes that have provided us with an increased understanding of oncogenesis. Furthermore, these findings have identified diagnostic and potentially prognostic factors for patient management. Molecular diagnostic techniques, such as reverse transcription PCR (RT-PCR) and fluorescence in situ hybridization (FISH), have become important tools for evaluating pediatric soft tissue tumors. By detecting characteristic fusion genes, these techniques have greatly increased the diagnostic accuracy of histopathological classification. One of the exciting promises of the development of these molecular techniques is their ability to detect micrometastasis and minimal residual disease. Monitoring of minimal residual disease in pediatric soft tissue tumors by quantitative RT-PCR may provide important prognostic information. Furthermore, the potential development of targeted therapy based on the understanding of the molecular pathology of a specific soft tissue tumor may complement existing treatments and improve disease outcome.

Chromosomal translocations and sarcomas

This review examines how the identification of tumor-specific translocations and fusion proteins has advanced the basic scientific and clinical understanding of sarcomas. Recent genetic advances, including the ASPL-TFE3 fusion of alveolar soft part sarcoma, the JAZF1-JJAZ1 fusion of endometrial stromal sarcoma, and HMGIC fusions in liposarcoma, are discussed. Next, the review addresses the ways in which molecular genetic data have influenced diagnostic and prognostic paradigms. For example, recent studies describe the detection of occult tumor cells and the identification of primary renal neoplasms that are genetically related to alveolar soft part sarcoma. In addition, the review discusses potential therapies based on the targeting of sarcoma-specific fusion proteins. These reports describe the potential use of Gleevec (STI571) for dermatofibrosarcoma protuberans and the use of tumor-specific fusion proteins as potential targets for immunotherapy. Finally, basic scientific findings are reviewed that elucidate, for example, the aberrant functions of SYT-SSX in chromatin remodeling and of EWS-FLI1 in transcription and mRNA splicing. These and other emerging models of tumorigenesis will help identify new therapeutic targets.