t(11;22) in three cases of peripheral neuroepithelioma

Limited Role of TP53 and TP53-Related Genes in Myxoid Liposarcoma

Aims

Circumstantial evidence suggests that genetic changes may lead to tumor progression within the myxoid liposarcoma tumors (MLTs) carrying non-random chromosomal translocation t(12;16).

Methods

To address this subject an immunophenotypic analysis, applying antibodies against proteins encoded by TP53, MDM2 and CDK4 genes, complemented by molecular analysis of eight suitable cases, was performed on 104 consecutive cases. Chromosomal translocations were assessed either by cytogenetic analysis or by RT-PCR in 9 suitable cases and chimeric transcripts were found in all cases but two pleomorphic liposarcomas.

Results

Based on immunophenotyping and tumor site, the case material consisted of three groups. The first one was made up of 92 non-retroperitoneal cases carrying a null p53, mdm2, cdk4 immunophenotype, which remained unchanged over the time of recurrences and along the gamut of histologic subtypes. The second group was represented by five p53+, mdm2-, cdk4- non-retroperitoneal cases, 4 of which were further analysed by PCR-SSCP for p53 mutation. The im-munophenotipic profile of these cases, complemented by the molecular findings, supported a role of TP53 in tumor progression in three high-grade MLTs. The third group, consisting of 7 retroperitoneal cases, showed a heterogeneous immunophenotype, sharing immunophenotypic and molecular features with the well-differentiated/evoluted (dedifferentiated) liposarcoma group.

Conclusions

TP53 mutations seem to play a role in tumor progression in a few cases of MLTs (2.8%) showing more aggressive histologic characteristics. The unexpected finding that a number of retroperitoneal LMTs display the immunophenotypic profile of the well differentiated/evoluted (dedifferentiated) liposarcomas, deserves further investigation.

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.

Wilms tumor in monozygous twins: clinical, pathological, cytogenetic and molecular case report

The concomitant occurrence of Wilms tumor (WT) was observed in two monozygotic twin sisters without evidence of congenital malformations. Twin 1 was diagnosed with a stage I WT at 11 months of age, whereas twin 2 developed a bilateral (stage V) WT at 13 months of age. In both cases pathologic examination showed a nonanaplastic stromal type WT, with marked rhabdomyomatous elements. Cytogenetic analyses performed on blood samples and on tumor specimens revealed no karyotypic abnormality. No alteration of the WT1 and POU6F2 genes was identified in constitutional and tumor DNA of both sisters, and no anomaly in WT1 expression was evidenced in the normal kidney of one of them. However, loss of heterozygosity on chromosome 11p, involving the alleles of maternal origin, was detected both in the single tumor of twin 1 and in the two distinct tumors of twin 2, thus suggesting a common etiology of the diseases. To the authors' knowledge, this is the first report describing at both the clinical and genetic level a couple of monozygotic twins concordant for WT development.

Relevance of cytogenetic and fluorescent in situ hybridization analyses in the clinical assessment of soft tissue sarcoma

Soft tissue sarcomas are a heterogeneous group of malignant tumors displaying a wide range of clinical presentations, morphological features, and biological behaviors. These characteristics and the recent development of differentiated treatment regimens for the different types of soft tissue sarcomas call for refined histological classification using additional ancillary approaches such as cytogenetic and molecular genetic analyses. We coupled classical cytogenetics and fluorescent in situ hybridization (FISH) on both metaphases and interphase nuclei to show the feasibility of this approach to characterize tumor type-specific chromosome rearrangements in soft tissue sarcomas of different histotype. In 35 cases analyzed, we detected the presence of specific chromosome rearrangements such as t(X;18) in synovial sarcoma (SS), t(12;16) in myxoid liposarcoma (MLS), t(11;22) in peripheral primitive neuroectodermal tumors (pPNET), t(2;13) in alveolar rhabdomyosarcoma (ARMS) and ring chromosomes in dermatofibrosarcoma protuberans (DFSP). In several cases, the presence of these cytogenetic rearrangements was of help for a differential diagnosis. The FISH analysis using painting probes not only confirmed the cytogenetic results but also allowed the identification of tumor-specific chromosome changes in those cases presenting low mitotic index or with poor quality chromosomes. Moreover, in the absence of analysable metaphases, FISH was successfully performed on interphase nuclei. Taken together, these results indicate both the diagnostic and clinical relevance of a molecular cytogenetic analysis in the study of soft tissue sarcomas.

Distinct mdm2/p53 expression patterns in liposarcoma subgroups: implications for different pathogenetic mechanisms

Recent findings have indicated that TP53 inactivation in sarcomas may result from mutation and/or deletion of the TP53 gene or, alternatively, from binding to the MDM2 gene products. To investigate further a possible role of the two genes in sarcomas, 24 large and deep-seated lipomas and 74 liposarcomas of various subtypes were analysed for mdm2 and p53 overexpression by immunocytochemistry. Nineteen cases of the same series were also molecularly analysed for both MDM2 gene amplification and TP53 mutations, and a further ten cases for non-random chromosomal abnormalities. In the retroperitoneal well-differentiated-dedifferentiated (WD-DD) group, 15/16 WD and 8/8 DD liposarcomas displayed the mdm2+/p53+ phenotype, consistent with MDM2 gene amplification in the absence of TP53 mutations. In the non-retroperitoneal WD-DD group, 5/11 WD liposarcomas also retained the mdm2+/p53+ phenotype whereas all DD liposarcomas showed an immunophenotype and, when assessed, a genotype consistent with mutant TP53. Null mdm2 immunophenotype, coupled with evidence of a specific chromosome translocation t(12;16), was constantly observed in both the usual and the cellular subtypes of myxoid liposarcoma, three cases of which also showed TP53 alterations at the genetic or protein level. Neither mdm2 nor p53 overexpression was observed in the lipomas. The results show the existence of three main pathogenetically distinct groups of liposarcoma. The first retroperitoneal WD-DD group, which represents a novel class of tumours within a single histological category of sarcoma, where MDM2-mediated inactivation of p53 could be related to the pathogenetic mechanism. The second is the non-retroperitoneal WD-DD group, where the TP53 mutations appear to correlate with the dedifferentiation process. The third is the myxoid group, which is characterized by its own unique cytogenetic profile and never shows any involvement of TP53 or MDM2 genes. As for diagnostic significance, the absence of mdm2 and p53 reactivity in lipomas seems to represent a useful marker for differential diagnosis from lipoma-like WD liposarcomas.

Chromosomal rearrangement t(11;22) in extraskeletal Ewing's sarcoma and primitive neuroectodermal tumour analysed by fluorescence in situ hybridization using paraffin-embedded tissue

The clonal chromosomal rearrangement t(11;22) has been reported by karyotypic analysis to be specific for Ewing's sarcoma of bone and soft tissue origin as well as primitive neuroectodermal tumour. In this report, immunohistological analysis of MIC 2 expression and fluorescence in situ hybridization (FISH) were performed using paraffin-embedded tissues. We examined t(11;22) in the nuclei isolated from two Ewing's sarcomas, four primitive neuroectodermal tumours, and three neuroblastomas, which served as negative controls by FISH with an alpha-satellite DNA probe for chromosome 11, a chromosome 22 marker probe, and whole chromosome painting probes for both chromosomes 11 and 22. Both cases of Ewing's sarcoma and the four primitive neuroectodermal tumour specimens were immunoreactive for MIC 2. Both Ewing's sarcomas and three of the four primitive neuroectodermal tumours contained the tumour-specific t(11;22), but the three neuroblastomas did not show this translocation. Based on the cytogenetic results and on the immunohistological investigation of MIC 2 expression, Ewing's sarcoma is suggested to be related closely to primitive neuroectodermal tumour. FISH is a useful aid in determining the tumour type of Ewing's sarcoma and putative related tumours.

Variant translocation t(6;10)(p21;q22) in pulmonary chondroid hamartoma

Banding cytogenetics and fluorescence in situ hybridization analysis of a pulmonary chondroid hamartoma (PHC) showed the presence of a t(6;10)(p21;q22). A cytogenetically identical translocation has previously been found in another case of PHC, suggesting that it could represent a variant form of the standard t(6;14)(p21;q24).

Involvement of chromosomes 17 and 22 in dermatofibrosarcoma protuberans

Literature on the cytogenetics of dermatofibrosarcoma protuberans (DFSP) is limited; only 10 cases with chromosome aberrations have been reported. They are karyotypically characterized by the presence of supernumerary ring(s), either as the sole cytogenetic abnormality or together with a few additional structural or numerical changes. We report the cytogenetic and fluorescence in situ hybridization (FISH) analysis of three new DFSP, one primary and two recurrent tumors. In two cases we found a supernumerary ring as the sole change, whereas the third had two copies of a marker chromosome and monosomy of chromosome 22. Sequences of chromosomes 17 and 22 were identified by FISH in the supernumerary rings and in the markers. The fluorescence pattern suggested that additional sequences were present in the two rings, but showed that the marker chromosomes were entirely painted by chromosome 17 and 22 probes. The findings indicate that juxtaposition and/or amplification of chromosome 17 and 22 sequences could be crucial in the pathogenesis of DFSP.

Cytogenetic abnormalities of small round cell tumours

Between 1987 and 1991, cytogenetic studies were carried out on small round cell tumours of 68 patients from the Northern Health Region of England. Clonal chromosome abnormalities were found in 30, comprising 15 neuroblastomas, 7 Ewing's tumours, 7 rhabdomyosarcomas, and 1 granular cell tumour. Characteristic rearrangements were found in five cases of Ewing's tumour [all with translocation t(11;22) (q24;q12)] and in four cases of rhabdomyosarcoma [all with evidence of translocation t(2;13) (q35-37;q14)]. In one case of Ewing's tumour and three of rhabdomyosarcoma, the cytogenetic findings were important in diagnosis. Within the neuroblastomas, examples were found of hyperdiploidy, 1p rearrangements, double minute chromosomes, and homogeneously staining regions, but too few cases were available for prognostic associations to be assessed. Our findings confirm the diagnostic importance of chromosome abnormalities in small round cell tumours and indicate that cytogenetic analysis should be an intrinsic part of the initial investigations of all patients with such tumours.

Cytogenetic characterisation of small round cell tumours using fine needle aspiration

Cytogenetic analysis of short term cultures of fine needle aspirates from two tumours, characterised cytologically as small round cell neoplasms, showed specific clonal chromosomal abnormalities. In both cases the cytogenetic finding of a t(11; 22) (q24; q12) helped determine their diagnosis as peripheral neuroectodermal tumours of the thoraco-pulmonary region (Askin's tumour). These findings suggest that cytogenetics can reliably distinguish neoplasms which present as undifferentiated small round cell tumours.

Two malignant peripheral primitive neuroepithelial tumor cell lines established from consecutive samples of one patient: characterization and cytogenetic analysis

A 6-year-old girl presented with a tumor of the right shoulder involving bone, adjacent soft tissue, and regional lymph nodes. The conventional histologic diagnosis was ambiguous, initially suggesting lymphoma. After relapse on lymphoma therapy, reevaluation with additional multiple diagnostic techniques performed on the biopsy tissue and on two cell lines derived from the biopsies established the diagnosis of a primitive neuroepithelial tumor of bone and soft tissue. This was strongly supported by 1) focal rosette formation by the tumor cells and positive immunostaining for neuron-specific enolase and synaptophysin, with absent staining for leukocyte common antigen; 2) at the ultrastructural level, formation of cellular processes containing microtubules, a paucity of neurosecretory granules, absence of synaptic junctions, formation of long "intermediate" junctions between cells, and, in culture, widespread development of rosettes; 3) marked surface positivity to W 6/32 and negativity to HSAN 1.2 antibodies; and 4) elevated expression of MYC and lack of overexpression of MYCN oncogenes. Numerical and structural abnormalities were present in the karyotype, but the expected t(11;22)(q24;q12) was not present in the tumor-involved marrow or in either of the established tumor cell lines, although there was an interstitial deletion of 11q involving breakpoints in q21 and q23.

Trisomy 8 in primary esthesioneuroblastoma

Esthesioneuroblastoma is a rare malignancy believed to be derived from neuroectodermal stem cells within the olfactory epithelium. We have obtained the karyotype of a primary esthesioneuroblastoma following brief (7-day) in vitro culture, and have determined that the only observable cytogenetic anomaly is the presence of an additional chromosome 8. Previously, the karyotypes of two cell lines established from metastatic esthesioneuroblastomas have been reported to contain the equivalent of three copies of chromosome 8, in addition to other chromosomal aberrations, including the reciprocal translocation, t(11;22)(q24;q12). Examination of the cytogenetic literature suggests that an extra copy of chromosome 8 is a common occurrence in undifferentiated small round cell tumors frequently observed to carry the t(11;22), including esthesioneuroblastoma, Ewing's sarcoma, peripheral neuroepithelioma, Askin's tumor, and rhabdomyosarcoma. These data, combined with our report of a small round cell tumor with the karyotype 47,XY, +8, indicate that trisomy 8 may be a common phenomenon in these tumors, and may also provide some sort of selective advantage to these tumor types.