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Biomedical subjects

I M Ambros

Publications and source records attributed to I M Ambros.

36 records · Page 2Linked to original sources
PubMed1996

Role of ploidy, chromosome 1p, and Schwann cells in the maturation of neuroblastoma.

BACKGROUND: Neuroblastoma is a heterogeneous disease, with manifestations ranging from spontaneous regression to lethal spread. Sometimes the tumor spontaneously differentiates toward a benign ganglioneuroma (maturing neuroblastoma). The prognosis is frequently related to ploidy, deletions in the short arm of chromosome 1, and amplifications of the N-myc oncogene. Maturing neuroblastomas consist of both neuronal cells and Schwann cells. We investigated the genetic composition of both cell types in maturing neuroblastomas, to determine the relation between genetic abnormalities and maturation. METHODS: We studied 20 maturing and mature neuroblastomas by in situ hybridization to count the chromosomes and evaluate possible deletions in the short arm of chromosome 1 in neuronal and Schwann cells. The DNA content of the cells was measured by flow cytometry. RESULTS: Neuroblastic and ganglionic cells showed aberrations in the number of chromosomes. In situ hybridization and flow cytometry demonstrated near-trip-loidy in 18 of 19 tumors and pentaploidy in the remaining tumor. The Schwann cells in all 20 neuroblastomas contained normal numbers of chromosomes. In 18 tumors studied, there were no chromosome 1 deletions in either type of cell. CONCLUSIONS: The Schwann cells in maturing neuroblastomas differ genetically from the neuronal cells. The normal number of chromosomes in Schwann cells and the abnormal number in neuroblastic ganglionic cells suggests that Schwann cells are a reactive population of normal cells that invade the neuroblastoma. Near-trip-loidy of neuroblastoma cells and intact chromosome 1 are presumably genetic prerequisites for spontaneous organoid maturation, because we found no diploidy or chromosome 1 depletions in the neuronal cells of spontaneously maturing neuroblastomas.

Child↗
PubMed1996

Connatal localized neuroblastoma. The case to delay treatment.

BACKGROUND: Spontaneous regression is well documented for a subset of widespread neuroblastomas (Stage 4S) and for localized residual tumors after incomplete resection. Possible spontaneous regression of untreated localized neuroblastoma in infants is frequently discussed, but has very rarely been demonstrated clinically. METHODS: We report four patients with localized neuroblastomas detected early; all were tumors of the adrenal gland. One patient was detected antenatally by ultrasound, the other three tumors were detected incidentally by sonography at age of birth, 1 week, and 7 weeks, respectively. In three patients treatment was delayed in order to await a possible spontaneous regression, and in one patient treatment was delayed due to an uncertain diagnosis. RESULTS: Local tumor growth was observed in three patients, and the tumors were removed 7, 12, and 16 weeks, respectively, after the initial diagnosis of the neuroblastoma. All three patients are free of disease. The fourth patient developed liver metastases 4 weeks after the first suspicion of neuroblastoma. Progressive disease ended in death at the age of 17 months. CONCLUSIONS: None of the four patients showed spontaneous tumor regression. Noninvasive examinations and invasive investigations (in two patients) were unable to predict the tumor's behavior. Based on present knowledge, a general "wait and see" strategy cannot be recommended for early and incidentally detected neuroblastoma patients.

Adrenal Gland Neoplasms↗
PubMed1996

Demonstration of the translocation der(16)t(1;16)(q12;q11.2) in interphase nuclei of Ewing tumors.

The der(16)t(1;16) has been detected cytogenetically in a number of malignancies including Ewing tumors (ETs). To enable fast and reliable analysis of der(16) chromosomes, we established an interphase cytogenetic approach. By using two DNA probes hybridizing to the heterochromatic portions on the long arms of chromosomes 1 and 16, this technique allows the detection of this chromosomal aberration in nonproliferating cells. Formation of the der(16) leads to partial excess of 1q material and partial loss of the long arm of chromosome 16. Double-target fluorescence in situ hybridization (FISH) experiments were performed on cytospin slides of 13 ETs, near-triploid tumor cells and normal cells to assess whether the FISH technique used permits the discrimination of nuclei harboring this aberration from nuclei without a der(16) chromosome. In five ETs, we found evidence for the presence of one or two der(16)t(1;16) chromosomes both by FISH and by conventional cytogenetics. Tumor cells displayed two signals for intact chromosomes 1, one or two additional fused signals for the der(16) chromosomes, and one signal for the intact chromosome 16. In one case without fused signals, the presence of a der(16) was demonstrated by hybridizing a painting probe for chromosome 16 simultaneously with the paracentromeric probe for chromosome 1. Our results suggest that double-target FISH on interphase nuclei offers an ideal tool for analyzing tumors prospectively and retrospectively to assess the biological role and the possible prognostic impact of the der(16) in ETs and in other solid tumors.

Adolescent↗
PubMed1996

Survival from locally invasive or widespread neuroblastoma without cytotoxic therapy.

PURPOSE: To test the hypothesis that cytotoxic therapy is not needed at diagnosis to assure the survival of most patients with non-stage 4 neuroblastoma. METHODS: Patients with non-stage 4 disease received no cytotoxic therapy in the absence of N-myc amplification. The International Neuroblastoma Staging System (INSS) was used. RESULTS: Of 84 consecutive patients with previously untreated, newly diagnosed neuroblastoma, 31 (37%) had non-stage 4 disease. All 31 patients initially received no cytotoxic therapy because none of them had N-myc amplification. Nine stage 1 patients are relapse-free. This report focuses on the 22 patients with locally invasive or distant disease: two stage 2A with gross residual tumor postsurgery, 11 stage 2B with ipsilateral or midline lymph node involvement, four stage 3, and five stage 4S. Eight of the 22 patients were older than 1 year. Postsurgery, 13 patients had visible residual disease, and two others had markedly increased urinary catecholamine levels for more than 1 year. Recurrent or enlarging tumors regressed spontaneously (n = 2) or were excised 5 to 39 months after diagnosis (n = 4). One of the latter had chromosome 1p deletions (common in poor-risk neuroblastoma) that were not detected in the patient's original tumor resected 23 months earlier--findings consistent with clonal evolution or multifocal disease. The patient received chemotherapy. All 22 patients are alive 24 to 98 months (median, 64) from diagnosis. CONCLUSION: Our results suggest that non-stage 4 patients without N-myc amplification can be spared cytotoxic therapy because (1) residual postsurgical or recurrent biologically favorable neuroblastoma rarely evolves into lethal stage 4 disease; and (2) neuroblastoma in lymph nodes has no prognostic significance. These findings are remarkable because no other cancer includes subtypes that are curable without therapy to ablate residual disease.

Adolescent↗
PubMed1996

International neuroblastoma staging system stage 1 neuroblastoma: a prospective study and literature review.

PURPOSE: To gain insight into the management of non-metastatic neuroblastoma by examining clinical and biologic features of International Neuroblastoma Staging System (INSS) stage 1 tumors. METHODS: Patients were staged by both the INSS and the Evans staging system and were evaluated for biologic prognostic factors. Patients with INSS stage 1 received no cytotoxic therapy. The literature was reviewed for clinical and biologic data about INSS stage 1. RESULTS: We evaluated 10 consecutive patients (median age, 17.5 months) with INSS stage 1; all remain disease-free (median follow-up duration, > 5 years). Tumors were in the abdomen (n = 6), chest (n = 3), or pelvis (n = 1). Neuroblastoma involved margins of resection in six tumors. Poor-prognostic biologic findings included tumor-cell diploidy (n = 2) and unfavorable Shimada histopathology (n = 2). Two patients were to receive chemotherapy for, respectively, a tumor deemed unresectable and a tumor classified as Evans stage III; second opinions resulted in surgical management alone in each case. Published reports confirm that some INSS stage 1 patients (1) are at risk for overtreatment, and (2) have poor-prognostic biologic findings yet do well. CONCLUSION: Surgery alone suffices for INSS stage 1 neuroblastoma, even if biologic prognostic factors are unfavorable, microscopic disease remains after surgery, and tumor size is suggestive of "advanced-stage" status in other staging systems. Attempts to resect regionally confined neuroblastomas should take precedence over immediate use of cytotoxic therapy; otherwise, some patients may receive chemotherapy or radiotherapy unnecessarily.

Adolescent↗
PubMed1996

[5 years neuroblastoma screening in Austria: rate of participation, results and a comparison with other screening areas].

In late 1990 a screening program for the early detection of neuroblastoma in infants was introduced in Austria. The program is performed on a voluntary basis in collaboration with general pediatricians and practitioners. Filter strips for urine collection are distributed to parents of infants aged seven to nine months on the occasion of a routine check up. The samples are sent to the laboratory by parents and analysed for vanillylmandelic acid (VMA) and homovanillic acid (HVA). Between January 1991 and December 1995 125,201 infants were screened. The compliance rate was 26.8% for Austria, but great differences were seen for different regions (65% in Carinthia, 10% in Vorarlberg). 30 children were admitted to hospital for investigation of repeatedly elevated urine catecholamines. A neuroblastoma was identified in 16 cases. In 12 of these cases at least one unfavorable prognostic factor was present (stage > or = 3, elevated LDH, unfavorable histology, N-myc amplification, di- or tetraploidy). Neuroblastoma screening of infants aged more than six months seems to detect predominantly those tumors which are unlikely to regress spontaneously. The observation of one false negative case, however, demonstrates that neuroblastomas which become clinically manifest at a later date may remain undetected by early screening. Possible advantages of shifting screening to a later age and repeated screening are discussed.

Austria↗
PubMed1995

High nm23-H1/NDPK-A expression in Ewing tumors: paradoxical immunohistochemical reactivity and lack of prognostic significance.

Expression of nm23-H1/NDPK-A has been reported to correlate inversely with metastasizing potential of rodent experimental cells and some human tumors. In the search for reliable molecular prognostic indicators for Ewing tumors (ET), a group of aggressive presumably neuroectodermal malignancies in children and adolescents, we studied nm23-H1/NDPK-A expression. Northern-blot and RT-PCR analyses were employed to semi-quantificatively measure nm23-H1 mRNA levels in ET cell lines and tissue extracts. A panel of monoclonal antibodies (MAbs) were used to evaluate protein abundance by Western blotting and immunohistochemistry. The nm23-H1/NDPK-A gene was also investigated on the DNA level to define possible genomic alterations. Our results revealed neither nm23-H1 allelic loss nor gene amplification and failed to show any significant variation in nm23-H1 mRNA or NDPK-A protein levels of primary or metastatic ET. NDPK-A protein levels were high and comparable to those of MCF-7 breast-cancer cells and to aggressive stage-IV neuroblastoma cell lines. nm23-H2/NDPK-B expression in ET was slightly more variable but generally lower than in MCF-7 cells. In the immunohistochemical analysis, however, discrepancies in the reactivity patterns with different antibodies were observed. Differential sensitivity to various fixation methods and heat treatment pointed to a structurally polymorphic NDPK-A protein. nm23-H1 expression studies using immunohistochemistry for prognostic counselling should thus be interpreted with caution.

Adolescent↗
PubMed1995

Regression and progression in neuroblastoma. Does genetics predict tumour behaviour?

Neuroblastoma (NB) is a heterogeneous disease. The clinical course may range from spontaneous regression and maturation to very aggressive behaviour. Stage 4s is a unique subcategory of NB, generally associated with good prognosis, despite skin and/or liver involvement and the frequent presence of tumour cells in the bone marrow. Another type of NB is the locally invasive tumour without bone and bone marrow involvement which can also have a good prognosis, irrespective of lymph node involvement. Unfortunately, there is only limited biological information on such tumours which have not been treated with cytotoxic therapy despite lymph node involvement, residual tumour mass after surgery and/or bone marrow infiltration. In order to find specific genetic changes common to NBs with a benign clinical course, we studied the genetic abnormalities of these tumours and compared them with highly aggressive tumours. We analysed a series of 54 localised and stage 4s tumours by means of in situ hybridisation performed on fresh cells or on paraffin embedded tissues. In addition, we performed classical cytogenetics, Southern blotting and PCR analysis on fresh tumour tissue. The majority of patients had been treated with surgery alone, and in a number of patients tumour resection was incomplete. Deletions at 1p36 and amplifications of the MYCN oncogene were absent, and diploidy or tetraploidy were not seen in any case, with residual localised tumours possessing a favourable outcome. Unexpectedly, one patient with a tetraploid 4s tumour without any genetic structural changes not receiving any cytotoxic treatment, did well. Interestingly, this genetic spectrum contrasted with that of progressing tumours, in which most had genetic aberrations, the deletion at 1p36 being the most common event. These data, although limited, suggest that an intact 1p36 (recognised by D1Z2), the absence of MYCN amplification and near-triploidy (at least in localised tumours), represent prerequisites for spontaneous regression and/or maturation.

Adolescent↗
PubMed1995

Schwann cells in neuroblastoma.

Why should we consider Schwann cells when we are interested in the biology of neuroblastomas (NBs)? Although we are familiar with the term "stroma-rich" NB, we basically think of a favourable prognostic subgroup, histologically distinguished by the development of a prominent Schwann cell-stroma. According to current opinion on the maturation processes in NBs, the NB-associated Schwann cell is believed to represent a differentiation product of the NB cell, and we therefore do not envisage the Schwann cell as having any important role in NBs. However, our interest was raised after having realised that Schwann cells in NBs are normal cells, very likely attracted to the neoplastic neuroblasts. But what role does this cell play in these tumours? Can we still reduce the appearance of Schwann cells in NBs to an epi-phenomenon or is this cell population responsible for the differentiation of certain NBs? If so, will it be possible to use their strategies to induce differentiation of neuroblasts and so render them non-aggressive, mature ganglionic cells? To shed light on the possible interactions between normal Schwann cells and NB cells, the maturation capacity of NBs and the genetic constitution of the two main cell populations in these tumours are briefly reviewed. Some data leading to the current view on the origin of the Schwann cells in NBs, and several physiological aspects of the Schwann cells, including normal neurone-Schwann cell interactions, are detailed.

Axons↗
PubMed1995

First experience with prognostic factors in unselected neuroblastoma patients. The Austrian Neuroblastoma 87 Study.

Between January 1987 and December 1993, 117 patients were registered in the Austrian A-NB87 study. The male/female ratio was 1.18, with 50 patients below the age of 1 year at diagnosis. Patients were assigned to stage according to the result of primary surgery in localised disease. Age, ferritin and neuron specific enolase were used in addition in stage III disease for risk-adapted treatment. Adrenal or pelvic primary tumour sites were mainly associated (81%) with advanced disease. The median observation time of the study is 3.5 years. The overall survival at 3 years was excellent in low stage disease and IVs patients, i.e. 100% for stage I and IIA (20 patients), 92% in stage IVs (13 patients), 81% in stage IIIA (18 patients) and 69% in stage IIB (8 patients). Stage IV (38 patients) showed a survival rate of 51%, whereas stage IIB (10 patients) had the worst outcome in this study, i.e. 20%, due to treatment-related toxicity. Significant unfavourable prognostic factors were neuron specific enolase (NSE) > 100 ng/ml, ferritin > 300 micrograms/ml and amplified MYCN. This study achieved a better survival rate in stage IV patients and a subgroup of stage III in comparison to our previous study (Pädiatrie und Pädologie 1986, 21, 269) and gives the basis to further reduce treatment intensity in low-risk disease based on biological factors. However, prognosis for high-risk cases was still poor in spite of a very aggressive treatment concept.

Age Factors↗
PubMed1994

Detection of numerical and structural chromosome abnormalities in pediatric germ cell tumors by means of interphase cytogenetics.

In contrast to the cytogenetically well characterized testicular germ cell tumors (GCT) in adults, reports on cytogenetic studies in pediatric GCT are scarce. The presence of an i(12p) and numerical abnormalities involving chromosome 12 are the most frequent cytogenetic changes in GCT of adults. We have performed in situ hybridization (ISH) studies on paraffin sections and on isolated nuclei of 13 pediatric GCT with particular emphasis on those chromosome abnormalities that are common in adult GCT. These include numerical and structural abnormalities of chromosomes 1 and 12 as well as numerical deviations of chromosomes 8, 10, X, and Y. The histological subsets of the tumors investigated included two dysgerminomas (DGE), one seminoma (SE), two embryonal carcinomas (EC), four mixed and two pure yolk sac tumors (YST), and one undifferentiated (IT) and one differentiated teratoma (TD). Similar to the GCT in adults, additional copies of chromosome 12 were the most frequently observed numerical abnormalities. In contrast to the findings in adult GCT, changes in the size of the pericentromeric hybridization signals of chromosome 12, suggesting the presence of i(12p) chromosomes, were found in only two cases. No chromosome abnormalities were found in the pure TD or in the TD cells of mixed tumors containing a YST component. In the YST portion, however, Ip deletions and/or numerical chromosome changes were present. Surprisingly, deletions of the short arm of chromosome I, del(I)(p36.3), were frequent in pediatric GCT and were the sole abnormality detected in two cases. The Ip36 deletions were present in all stage-IV EC and YST investigated and were absent in the relatively benign TD and in one YST stage-I. Therefore, Ip36 deletions may have value as a prognostic marker in pediatric GCT.

Adolescent↗
PubMed1993

Detection of Ip36 deletions in paraffin sections of neuroblastoma tissues.

Nonradioactive in situ hybridization (NISH) on sections of paraffin-embedded neuroblastoma tissue was performed to evaluate numerical and structural aberrations of chromosome 1. Two biotinylated probes specific for the heterochromatic (D1Z1) and subtelomeric regions of chromosome 1 (D1S32) were used to study normal tissue and 4 neuroblastoma samples with and without Ip36 deletions. The NISH findings in 3 of the 4 neuroblastomas correlated well with the results obtained by cytogenetic banding analysis. In 1 tumor sample, however, a deletion at Ip36 was observed by NISH, both on metaphase spreads and interphase nuclei, but not by cytogenetics. The NISH method is therefore advantageous when only paraffin-embedded material is available and can be even more sensitive than conventional cytogenetic analyses under certain conditions. Moreover, the technique provides morphological information that cannot be obtained by methods relying on tissue extracts or cell suspensions.

Aneuploidy↗
PubMed1991

MIC2 is a specific marker for Ewing's sarcoma and peripheral primitive neuroectodermal tumors. Evidence for a common histogenesis of Ewing's sarcoma and peripheral primitive neuroectodermal tumors from MIC2 expression and specific chromosome aberration.

This study reports on the specific expression of the MIC2 gene, a pseudoautosomal gene located on the short arms of the X and Y chromosomes, on Ewing's sarcoma (ES) and peripheral primitive neuroectodermal tumor (pPNET) cells. The gene product, a cell membrane protein, is recognized by the newly established monoclonal antibody (MoAb) HBA-71 and the previously described MoAb 12E7 and RFB-1. Furthermore, the reaction pattern of the MIC2 antibodies, especially HBA-71, with normal tissues and a great number of benign and malignant tumors (70 different tumors, 199 tumor samples), as well as the correlation between the specific chromosomal aberrations, i.e., the t(11;22) and the del(22) and the expression of this antigen, are demonstrated. Both ES and pPNET cells express the MIC2 gene in very high amounts, which represents a highly selective and almost unique feature of these cells, making an assignment of these tumors in one entity even more likely. The MIC2 antibodies are of great value for clinical and research purposes.

12E7 Antigen↗
PubMed1990

Overexpression of the pseudoautosomal gene MIC2 in Ewing's sarcoma and peripheral primitive neuroectodermal tumor.

Ewing's Sarcoma (ES), the second most frequent bone tumor in childhood and adolescence, and the probably closely related peripheral primitive neuroectodermal tumor (pPNET) share a unique cytogenetic translocation between chromosomes 11 and 22. Both of them expose high amounts of a glycoprotein on their cell surface, which can be specifically detected by the mAb HBA-71. The cDNA coding for the HBA-71 antigen was isolated by screening a cDNA expression library constructed from a pPNET-derived cell line. Nucleotide sequencing revealed the HBA-71 antigen to be the product of the pseudoautosomal gene MIC2 previously identified by the mAb 12E7 in haematopoietic cells. This antigen is a glycoprotein with a molecular weight of about 29,000 and is expressed in low amounts in most human cell lines and probably normal tissues and tumors with only a few exceptions. In T-cells the antigen is involved in cell adhesion processes. In ES- and pPNET-derived cell lines MIC2 expression is significantly enhanced. No gross changes in posttranslational modification could be observed. The high expression results in easy and specific detection of the antigen in immunocytochemical analysis of paraffin embedded tissue sections making HBA-71 a useful tool in tumor diagnosis.

12E7 Antigen↗
PubMedDate not supplied

[Value of prognostic factors in the Austrian A-NB87 Neuroblastoma Study].

AIMS: A multivariate analysis was performed to evaluate the impact of various prospectively evaluated risk factors. PATIENTS AND METHODS: From January 1987 to December 1993, 120 patients were registered in the study. 108/120 patients were eligible. There were 49 girls and 59 boys with a median age at diagnosis of 14 months (range, 0 to 224 months). Patients were classified according to the Evans classification system. LDH, NSE, Ferritin, N-myc amplification, 1p-deletion and ploidy were evaluated at diagnosis. Treatment intensity was based on the results of primary surgery: surgery only for 22 (20%) stage I and IIA patients (macroscopic residue without lymph node involvement), the 9 IIB patients (8,5%) (macroscopic residue with lymph node involvement) had mild chemotherapy in addition (6 x VCR/CYC) and elective radiation (Rx). Stage III patients were divided into 2 groups: IIIA patients (n = 17/16%) had to have ferritin levels under 300 micrograms/ml, NSE lower than 100 ng/ml and age below 2 years at diagnosis and received 6 alternating cycles of DAMO/ MVDOC. If one of these three criteria was not fulfilled, patients were assigned to the more intensive treatment arm stage IIIB (n = 12/11%), i.e. 9 alternating cycles of DAMO/MVDOC/IPE. Stage IV pts (n = 35/32.5%) received 8 MVDOC/IPE cycles and 20 patients received megatherapy followed by stem cell reinfusion in addition. 13 stage IVs patients (12%) were registered and had elective VCR/CYC and/or liver radiation in case of poor clinical condition. The median observation time is 4.2 years (range, 1 to 7.5). RESULTS: The survival rate at 3 years was excellent for localized disease and stage IVs with survival rates of 100% for stage I/IIA and 92% for stage IVs. Stage IIIA patients had an EFS rate of 81% whereas stage IIB patients achieved only 69%. Stage IV patients reached 51%, however outcome was especially poor for stage IIIB patients (20%) due to treatment related toxicities. The toxic death rate in the study was 13% (2 surgical deaths, 8 infections, 4 multiple organ failures). Univariate analysis demonstrated the following significant unfavorable risk factors: age over 1 year at diagnosis (58/108 pts, p = 0.006), NSE > 100 ng/ml (26/95 pts, p < 0.0001), Ferritin > 300 ng/ml (19/98 pts, p = 0.007), LDH > 300 (400) U/L, 51/87 pts, p = 0.004), presence of N-myc amplification (17/59 pts, p = 0.001), deletion of the short arm of chromosome 1 (19/74 pts, p < 0.0001) and di/tetraploidy (32/72 pts, p = 0.008). The power of these factors was even stronger in patients with localized disease whereas no significant prediction was observed for stage IV patients. Furthermore a significant correlation of the serological (NSE, ferritin, LDH) and biological factors (N-myc, deletion 1p, di/tetraploidy) was detected in this study. Only NSE was identified as an independent prognostic factor (p = 0.018) whereas no independent factor could be identified within the 3 biological parameters due to their high correlations (Kendall's tau for N-myc and deletion 1p:0.7). However, N-myc (p = 0.005) as well as deletion 1p (p = 0.01) were found significantly more important than di/tetraploidy. CONCLUSIONS: Biological classification of neuroblastomas should be mandatory and be the prerequisite for any risk adapted treatment. One serological and 2 biological factors could be a good standard evaluation to identify neuroblastoma patients at risk.

Adolescent↗
PubMedDate not supplied

[Cytogenetic aspects of pediatric germ cell tumors].

We have performed in situ hybridization (ISH) studies predominantly on paraffin sections and on isolated nuclei of 22 pediatric germ cell tumors (GCTs) from 18 patients including 4 recurrences from three patients. In addition, we performed conventional cytogenetic analyses in three tumor samples. Because reports on cytogenetic studies in pediatric GCTs are scarce we focused our studies on those chromosome abnormalities frequently observed in adult GCTs. These included numeric and structural abnormalities of chromosomes 1 and 12 (e.g. isochromosome 12p) and numeric deviations of chromosomes 8, 10, X and Y. The histological subsets of the tumors investigated included two dysgerminomas (DGE), one seminoma (SE), one combined seminoma, two embryonal carcinomas (EC), two recurrent ECs, six pure yolk sac tumors (YST), five combined teratomas, one immature teratoma (IT) and two recurrences of IT, and three differentiated teratomas (TD). Similar to the GCTs in adults, additional copies of chromosome 12 were the most frequently observed numeric abnormalities. The analysis of two paraffin-embedded tumors suggested that changes in the size of the pericentromeric hybridization signals of chromosome 12 may be attributed to the presence of i(12)(p10). This was confirmed following the karyotype analysis of one EC which unequivocally revealed the presence of two i(12)(p10). Interestingly, using these probes, no chromosomal abnormalities were found in the pure TD or in the TD cells of mixed tumors containing a YST component. In the YST portion, however, the 1p deletions and/or numeric chromosome changes were present. Surprisingly, deletions at the short arm of chromosome 1, del(1)(p36.3), were frequently observed in malignant pediatric GCTs and were the sole abnormality detected in one case.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗