New developments in the pathology and molecular biology of retroperitoneal sarcomas

Retroperitoneal sarcomas (RPS) refer to a heterogeneous group of malignancies of mesenchymal origin developing from retroperitoneal tissues and vessels. The most frequent RPS are well differentiated/dedifferentiated liposarcomas and leiomyosarcomas, but other rare histological subtypes can be observed. Over the last decade, significant advances have been made in the pathological and molecular characterization of sarcomas. These advances have led to major changes in their diagnostic management as well as in the development of new therapeutic strategies based on tumor biology and microenvironment. This review describes the current knowledge and recent findings in the pathology and molecular biology of the most frequent RPS subtypes.

The molecular landscape of well differentiated retroperitoneal liposarcoma

Well differentiated liposarcoma (WD-LPS) is a relatively rare tumour, with fewer than 50 cases occurring per year in the UK. These tumours are both chemotherapy- and radiotherapy-resistant and present a significant treatment challenge requiring radical surgery. Little is known of the molecular landscape of these tumours and no current targets for molecular therapy exist. We aimed to carry out a comprehensive molecular characterisation of WD-LPS via whole genome sequencing, RNA sequencing, and methylation array analysis. A recurrent mutation within exon 1 of FOXD4L3 was observed (chr9:70,918,189A>T; c.322A>T; p.Lys108Ter). Recurrent mutations were also observed in Wnt signalling, immunity, DNA repair, and hypoxia-associated genes. Recurrent amplification of HGMA2 was observed, although this was in fact part of a general amplification of the region around this gene. Recurrent gene fusions in HGMA2, SDHA, TSPAN31, and MDM2 were also observed as well as consistent rearrangements between chromosome 6 and chromosome 12. Our study has demonstrated a recurrent mutation within FOXD4L3, which shows evidence of interaction with the PAX pathway to promote tumourigenesis. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Renal metastases from esophageal cancer and retroperitoneal lymphoma detected via chromosome duplications identified by fluorescence in situ hybridization in urine exfoliated cells: First 2 case reports

RATIONALE

Renal-occupying lesions positive for urine fluorescence in situ hybridization (FISH) are usually considered urothelial carcinomas. Here, we describe 2 cases of renal metastases with chromosome duplications in urine exfoliated cells.

PATIENT SYMPTOMS

Patient 1, a 56-year-old male with a history of esophageal cancer, was admitted to our hospital on May 2017 after presenting with right back pain with microscopic hematuria for 1 month. Magnetic resonance imaging (MRI) showed right renal space-occupying lesions (5.4 cm × 4.6 cm) and multiple enlarged lymph nodes in the right renal hilum and retroperitoneum. The cystoscopy results were negative, and FISH analysis of urine exfoliated cells was positive, indicative of chromosome 3, 7, and 17 amplifications. Patient 2 was a 50-year-old male who was admitted to our hospital on May 2019 with no obvious cause of abdominal pain and abdominal distension (lasting for 7 days), with a serum creatinine level of 844 μmol/L. Patient 2 had no hematuria or fever, and MRI showed left renal inferior and medial space-occupying lesions, and multiple mesenteric nodules at the junction of the left adrenal gland, retroperitoneum, abdomen, and pelvis, which were partially fused. The tumor lesions were approximately 3.1 cm × 2.3 cm in size. The urine FISH results were positive, indicating chromosome 3, 7, and 17 amplifications.

DIAGNOSES

Both patients were diagnosed with renal tumors with unknown pathology.

INTERVENTIONS

Patient 1 underwent laparoscopic resection of the kidney and ureter, and sleeve cystectomy. The postoperative pathological diagnosis was metastatic keratinized squamous cell carcinoma, with squamous cell carcinoma in the right hilar lymph node. Histological FISH of the primary esophageal cancer and renal metastases were consistent with the urine FISH test results. Patient 2 underwent a biopsy of the left renal inferior and retroperitoneal areas, and was diagnosed with diffuse large B-cell lymphoma.

OUTCOMES

Patient 1 survived 6 months after urological surgery. After treating patient 2 with the R-CHOP regimen and kinase inhibitors, his renal function recovered significantly and the mass become undetectable.

LESSONS

Our results imply that FISH-positive renal occupying lesions should be considered as potential renal metastases with chromosome aberrations when making a differential diagnosis.

A review of retroperitoneal liposarcoma genomics

Retroperitoneal liposarcomas are rare tumours that carry a poorer prognosis than their extremity counterparts. Within their subtypes - well differentiated (WDL), dedifferentiated (DDL), myxoid (MLS) and pleomorphic (PLS) - they exhibit a diverse genomic landscape. With recent advances in next generation sequencing, the number of studies exploring this have greatly increased. The recent literature has deepened our understanding of the hallmark MDM2/CDK4 amplification in WDL/DDL and addressed concerns about toxicity and resistance when targeting this. The FUS-DDIT3 fusion gene remains the primary focus of interest in MLS with additional potential targets described. Whole genome sequencing has driven identification of novel genes and pathways implicated in WDL/DDL outside of the classic 12q13-15 amplicon. Due to their rarity; anatomical location and histologic subtype are infrequently mentioned when reporting the results of these studies. Reports can include non-adipogenic or extremity tumours, making it difficult to draw specific retroperitoneal conclusions. This narrative review aims to provide a summary of retroperitoneal liposarcoma genomics and the implications for therapeutic targeting.

miR-34b/c rs4938723 T>C Decreases Neuroblastoma Risk: A Replication Study in the Hunan Children

Neuroblastoma is the most common seen solid neural tumor in children less than age one. As mutation in the miR-34b/c gene is observed in several types of human malignancies, there likely to be similar events that contribute to the pathogenesis of neuroblastoma. We hypothesize that polymorphism in the miR-34b/c gene might predispose to neuroblastoma. Here, we conducted this replication study by genotyping rs4938723 T>C from miR-34b/c in Hunan children (162 subjects with neuroblastoma and 270 control subjects) and examined its effect on the risk of neuroblastoma. We determined such association using logistic regression, adjusted for age and gender. Relative to those with TT genotype, subjects with C allele had reduced neuroblastoma risk (TC vs. TT: adjusted OR = 0.46, 95%CI = 0.30-0.71; additive model: adjusted OR = 0.64, 95%CI = 0.47-0.88; TC/CC vs. TT: adjusted OR = 0.49, 95%CI = 0.33-0.73). Stratified analysis revealed that rs4938723 TC/CC carriers were less likely to develop neuroblastoma for patients in the subgroups of age ≤ 18 months, age > 18 months, females, males, tumors in retroperitoneal, tumors in other sites, and clinical stages II, III, IV, and III+IV. Our findings verified miR-34b/c rs4938723 C variant allele as a protective factor for the risk of neuroblastoma. Further investigation of how miR-34b/c rs4938723 T>C might modify neuroblastoma risk is warranted.

HOTAIR gene polymorphisms contribute to increased neuroblastoma susceptibility in Chinese children

BACKGROUND

Neuroblastoma is the most frequently diagnosed extracranial solid tumor in children. Previous studies have shown that single-nucleotide polymorphisms in some genes are associated with the risk of multiple cancers, including neuroblastoma. Although Hox transcript antisense intergenic RNA (HOTAIR) gene polymorphisms have been investigated in a variety of cancers, to the authors' knowledge the relationships between HOTAIR gene polymorphisms and neuroblastoma susceptibility have not been reported to date. The objective of the current study was to evaluate the correlation between HOTAIR gene polymorphisms and neuroblastoma risk in Chinese children.

METHODS

The authors genotyped 6 polymorphisms (rs920778 A>G, rs12826786 C>T, rs4759314 A>G, rs7958904 G>C, rs874945 C>T, and rs1899663 C>A) of the HOTAIR gene in 2 Chinese populations including 393 neuroblastoma cases and 812 healthy controls. The strength of the associations was evaluated using odds ratios and 95% confidence intervals. Further stratification analyses were conducted to explore the association between the HOTAIR gene polymorphisms rs12826786 C>T, rs874945 C>T, and rs1899663 C>A with neuroblastoma susceptibility in terms of age, sex, clinical stage of disease, and sites of origin.

RESULTS

The authors found that the rs12826786 C>T (P =.013), rs874945 C>T (P =.020), and rs1899663 C>A (P =.029) polymorphisms were significantly associated with increased neuroblastoma risk. In stratification analyses, these associations were more predominant in females and among patients with tumor in the retroperitoneal region or mediastinum. The remaining 3 polymorphisms were not found to be related to neuroblastoma susceptibility.

CONCLUSIONS

The results of the current study verified that HOTAIR gene polymorphisms are associated with increased neuroblastoma risk and suggest that HOTAIR gene polymorphisms might be a potential biomarker for neuroblastoma susceptibility. Cancer 2018;124:2599-606. © 2018 American Cancer Society.

A subset of fat-predominant angiomyolipomas label for MDM2: a potential diagnostic pitfall

Angiomyolipomas (AMLs) are typically benign mesenchymal tumors with variable histologic composition. Fat-predominant AMLs can mimic well-differentiated liposarcomas (WDLSs) both radiographically and histologically because of the abundance of fat with admixed atypical cells resembling lipoblasts. However, the treatment and prognosis of AMLs and WDLSs are vastly different. Immunohistochemistry for murine double minute 2 (MDM2) has been used to support a diagnosis of WDLS; however, MDM2 labeling has not been specifically evaluated in fat-predominant AMLs. Here, we evaluated MDM2 immunohistochemistry in 36 AMLs (including 14 conventional AMLs, 13 fat-predominant AMLs, 6 fat-rich AMLs, 3 epithelioid AMLs) and 10 WDLSs. In addition, we labeled cases for HMB45, calponin, or actin, which are immunostains traditionally used to label AML. We performed fluorescence in situ hybridization (FISH) for MDM2 amplification on selected cases. By immunohistochemistry, 14% (5/36) of AMLs were MDM2+, including 23% (3/13) of fat-predominant AMLs. All MDM2+ AMLs evaluated by FISH (n=4) were negative for MDM2 amplification. By immunohistochemistry, 90% of WDLSs were MDM2+, and both MDM2+ WDLSs evaluated by FISH (n=2) were MDM2 amplified. All 36 AMLs labeled with HMB45 and calponin or actin. No WDLS labeled with HMB45; however, 80% of WDLSs labeled with calponin or actin. Although uncommon, MDM2 labeling is seen in a subset of fat-predominant AMLs and is a potential diagnostic pitfall in the evaluation of fatty tumors of the retroperitoneum. HMB45 is more sensitive and specific for AML than calponin or actin, and an immunopanel containing both HMB45 and MDM2 may be warranted to distinguish between fat-predominant AML and WDLS in histologically ambiguous cases.

Congenital Retroperitoneal Teratoma in Neurofibromatosis Type 1

Neurofibromatosis type 1 (NF1) is caused by mutations in the tumor suppressor gene NF1. The increased tumor risk in affected individuals is well established, caused by somatic biallelic inactivation of NF1 due to loss of heterozygosity. Pediatric teratoma has not been reported in individuals with NF1 previously. We report a case of congenital teratoma in an infant with a heterozygous maternally inherited pathogenic NF1 mutation (c.[1756_1759delACTA] and p.[Thr586Valfs*18]). We detected a "second hit" in the form of mosaic whole NF1 deletion in the tumor tissue using multiplex ligation-dependent probe amplification, as a proof to support the hypothesis of NF1 involvement in the pathogenesis of teratoma.

Pyrosequencing-Based Assays for Rapid Detection of HER2 and HER3 Mutations in Clinical Samples Uncover an E332E Mutation Affecting HER3 in Retroperitoneal Leiomyosarcoma

Mutations in Human Epidermal Growth Factor Receptors (HER) are associated with poor prognosis of several types of solid tumors. Although HER-mutation detection methods are currently available, such as Next-Generation Sequencing (NGS), alternative pyrosequencing allow the rapid characterization of specific mutations. We developed specific PCR-based pyrosequencing assays for identification of most prevalent HER2 and HER3 mutations, including S310F/Y, R678Q, L755M/P/S/W, V777A/L/M, 774-776 insertion, and V842I mutations in HER2, as well as M91I, V104M/L, D297N/V/Y, and E332E/K mutations in HER3. We tested 85 Formalin Fixed and Paraffin Embbeded (FFPE) samples and we detected three HER2-V842I mutations in colorectal carcinoma (CRC), ovarian carcinoma, and pancreatic carcinoma patients, respectively, and a HER2-L755M mutation in a CRC specimen. We also determined the presence of a HER3-E332K mutation in an urothelial carcinoma sample, and two HER3-D297Y mutations, in both gastric adenocarcinoma and CRC specimens. The D297Y mutation was previously detected in breast and gastric tumors, but not in CRC. Moreover, we found a not-previously-described HER3-E332E synonymous mutation in a retroperitoneal leiomyosarcoma patient. The pyrosequencing assays presented here allow the detection and characterization of specific HER2 and HER3 mutations. These pyrosequencing assays might be implemented in routine diagnosis for molecular characterization of HER2/HER3 receptors as an alternative to complex NGS approaches.

A Patient with an Extra-adrenal Pheochromocytoma and Germ-line SDHB Mutation Accompanied by an Atypical Meningioma

The gene succinate dehydrogenase subunit B (SDHB) encodes a protein comprising part of the mitochondrial complex II, which links the Krebs cycle and the electron-transport chain. Heterozygous germ-line SDHB mutations causes familial pheochromocytoma-paraganglioma syndrome and has also been linked to gastrointestinal stromal tumors, as well as renal cell carcinomas. We herein report a patient with a germ-line SDHB mutation who presented with an atypical meningioma that was identified as originating from a somatic SDHB mutation. The 41-year-old man, who had a surgical history of extra-adrenal pheochromocytoma at 23 years of age, recently developed gait disorder and hypertension. At the radiological examination, a tumor was detected in the cervical spinal cord at the C6-7 intervertebral level. The pathological findings of the isolated tumor were atypical meningioma assessed as grade II according to the World Health Organization criteria. Inherited neoplasia syndrome was suspected because of the patient's history of early-onset extra-adrenal pheochromocytoma and the development of meningioma. We therefore performed molecular genetic analyses. A direct sequence analysis revealed a heterozygous germ-line frameshift mutation in SDHB, specifically an 11-nucleotide deletion, c.305-315delCAATGAACATC, in exon 4, resulting in a frameshift p.A102EfsX12. Additionally, the sequence analysis of the tumor DNA revealed only a mutated allele with a frameshift mutation in the germ-line SDHB. Our findings suggest that SDHB plays an important role in the pathogenesis of meningiomas as well as pheochromocytomas. Therefore, a differential diagnosis for metastatic pheochromocytoma and other new onset tumors, including meningioma, particularly in patients with germ-line SDHB mutations and a previous history of pheochromocytoma should be carefully made.

The architecture and evolution of cancer neochromosomes

We isolated and analyzed, at single-nucleotide resolution, cancer-associated neochromosomes from well- and/or dedifferentiated liposarcomas. Neochromosomes, which can exceed 600 Mb in size, initially arise as circular structures following chromothripsis involving chromosome 12. The core of the neochromosome is amplified, rearranged, and corroded through hundreds of breakage-fusion-bridge cycles. Under selective pressure, amplified oncogenes are overexpressed, while coamplified passenger genes may be silenced epigenetically. New material may be captured during punctuated chromothriptic events. Centromeric corrosion leads to crisis, which is resolved through neocentromere formation or native centromere capture. Finally, amplification terminates, and the neochromosome core is stabilized in linear form by telomere capture. This study investigates the dynamic mutational processes underlying the life history of a special form of cancer mutation.

Building through breaking: the development of cancer neochromosomes

In this issue of Cancer Cell, Garsed and colleagues combine chromosome flow sorting and deep sequencing to characterize the structure of oncogene-containing neochromosomes in liposarcoma and provide evidence that they are generated by a combination of multiple dynamic and destructive processes.

MED12 exon 2 mutations in uterine and extrauterine smooth muscle tumors

Mutations in exon 2 of the MED12 gene have been reported in 50% to 70% of uterine leiomyomas. To determine the frequency of MED12 mutations in various types of smooth muscle tumors as well as normal uterine myometrium adjacent to a leiomyoma, we selected a total of 143 cases for analysis of MED12 exon 2 mutations by polymerase chain reaction and Sanger sequencing. MED12 mutations were detected in 54% of classical uterine leiomyomas (15/28) and in 15% of cases in myometrium adjacent to leiomyomas (2/13); 34% of leiomyoma/leiomyomatosis in pelvic/retroperitoneal sites (10/29); 0% of extrauterine leiomyomas (0/29); 8% of smooth muscle tumor of uncertain malignant potential (1/12); 30% of uterine leiomyosarcomas (6/20); and 4% of extrauterine leiomyosarcomas (1/25). Mutations were clustered around codons 44, 40, 41, and 36, and consisted primarily of single nucleotide substitutions and small in-frame deletions. Our results confirm the findings of similar recent studies and further show that pelvic and retroperitoneal leiomyomas harbor an increased frequency of MED12 mutations (34%) as compared with other extrauterine sites (0%; P = 0.0006), and that histologically unremarkable adjacent myometrium can harbor similar MED12 mutations. These findings suggest that smooth muscle tumors in pelvic/retroperitoneal sites are subject to the same mutational changes as those of uterine myometrium, and that these mutations may precede the gross or histological development of a leiomyoma.

[Familial paraganglioma syndrome: phenotype and relevance of a new SDHB mutation]

BACKGROUND AND OBJECTIVE

Advances in molecular biology have discovered new genes involved in the development of familial paraganglioma syndrome (PGL) including those encoding mitochondrial succinate dehydrogenase complex (SDH). We describe the diagnosis, clinical expression and genetic counselling in a family diagnosed of PGL due to a new SDHB mutation.

PATIENTS AND METHOD

Genetic study by PCR-direct sequencing SDHB gene and biochemical determination in blood/urine fractionated catecholamine 24h, metanephrines and conventional (computed tomography/magnetic resonance imaging) and functional imaging ((123)I-MIBG) in all members of a family diagnosed of PGL.

RESULT

DNA sequencing showed a non-described SDHB heterozygous mutation (c.287-3C>G intron3/exon4) in 5 of the subjects (71%). The estimated penetrance of the mutation's carriers was 40%, with a mean age of 35 years at diagnosis. All patients with active illness required surgical treatment after imaging and laboratory confirmation.

CONCLUSIONS

We describe the pathogenicity, diagnostic algorithm, genetic counselling and clinical expression of a new SDHB mutation (c.287-3C>G) in a family diagnosed of PGL.

A SDHB malignant paraganglioma with dramatic response to temozolomide-capecitabine

Ten percent of paragangliomas are malignant and one-third occurs in a genetic background. We report a case of succinate dehydrogenase subunit B (SDHB)-related malignant paraganglioma with dramatic response to temozolomide and capecitabine regimen (decrease in tumor size of 70% with RECIST criteria). Tumor cells harbored a new mutation in SDHB gene and showed aberrant hypermethylation of O6-methylguanine-DNA-methyltransferase promoter. Our report suggests the importance of molecular predictive factors of response for the selection of chemotherapeutic as well as targeted agents. This observation points to a possible genotype response to treatment relationships, which could help to design tailor-made treatments in the future.

Retrocaval mass in patient with von Recklinghausen disease: case report

Type I Neurofibromatosis (NF1) is an autosomal-dominant inheritable disorder, with an incidence of 1:3,000, and a prevalence of 1:4,000 to 5,000. Pathogenesis is based on mutations of the NF1 gene, a tumor suppressor gene encoding a cytoplasmic protein named neurofibromin that controls cellular proliferation. Patients affected by NF1 typically present with cutaneous neurofibromas, cafè au lait spots and eye involvement, but they can also be affected by various visceral tumors, such as neurofibromas (nodular or plexiform type), gastrointestinal stromal tumors or endocrine tumors, such as pheochromocytomas. Visceral neurofibromas are often asymptomatic but when growing in size they may present with pain, palpable abdominal mass, symptoms secondary to bowel obstruction or main vessels compression, and even gastrointestinal bleeding when mucosa or submucosa are involved. In these cases surgery becomes mandatory in order to remove all neoplastic tissue. The Authors describe a case of a young man affected by NF1 with associated retrocaval abdominal mass with compression and displacement of the inferior vena cava, thus requiring a complex surgical procedure.

Detection of alveolar rhabdomyosarcoma in pleural fluid with immunocytochemistry on cell block and determination of PAX/FKHR fusion mRNA by reverse transcription-polymerase chain reaction

BACKGROUND

Alveolar rhabdomyosarcoma is a primitive malignant round cell neoplasm, which shows skeletal muscle differentiation. Although their histopathologic and immunohistochemical findings are well known, the cytology, immunocytochemistry and molecular study on pleural effusion have not been well documented.

OBJECTIVE

To apply molecular method in the diagnosis and monitoring of alveolar rhabdomyosarcoma.

CASE REPORT

The case of a 14-year-old Thai male, who presented with dyspnea and left pleural effusion. Computed tomography of the chest and abdomen showed a huge heterogeneous enhancing mass at the left retroperitoneum. Pleural fluid cytology showed malignant small round blue cells. Immunocytochemical stains on cell block material showed positive reactivity to vimentin, sarcomeric actin, desmin, MyoD1, myogenin, and CD56 in round cell tumor Reverse transcription-polymerase chain reaction (RT-PCR) demonstrated PAX/FKHR fusion transcript. The patient received chemotherapeutic regimen for advanced-stage rhabdomyosarcoma. Finally, he succumbed to the disease, thirteen months after the diagnosis.

CONCLUSION

Immunocytochemistry on cell block in conjunction with determination of PAX/FKHR fusion mRNA by RT-PCR is a molecular method in the diagnosis and monitoring of alveolar rhabdomyosarcoma inpleural fluid.

Predominant expression of mutated allele of the succunate dehydrogenase D (SDHD) gene in the SDHD-related paragangliomas

Recent studies indicate that succinate dehydrogenase (SDH) genes B, C, or D are, at least partly, involved in the pathogenesis of pheochromocytoma or paraganglioma. Of these three genes, the SDHD gene mutation is most closely related with paragangliomas of the neck. Here we describe a case of an SDHD-related paraganglioma, in which we studied the molecular characteristics of an SDHD mutation to evaluate the involvement of SDHD in neck paragangliomas. Genetic testing revealed a heterozygous G106D mutation in the SDHD gene. In the tumor tissue, loss of heterozygosity was demonstrated by real time polymerase chain reaction (PCR). In the present case of SDHD mutated paragangliomas, wild type SDHD gene expression was markedly reduced possibly due to loss of heterozygosity not due to imprinting of SDHD gene in the tumors.

Novel mutation (L157X) in the succinate dehydrogenase B gene (SDHB) in a Japanese family with abdominal paraganglioma following lung metastasis

Recently, nuclear genes encoding two mitochondrial complex II subunit proteins, SDHD and SDHB, have been found to be associated with the development of familial pheochromocytomas and paragangliomas (hereditary pheochromocytoma/paraganglioma syndrome: HPPS). Growing evidence suggests that the mutation of SDHB is highly associated with abdominal paraganglioma and the following distant metastasis (malignant paraganglioma). In the present study, we report the case of a novel SDHB mutation (L157X) in a Japanese patient with abdominal paraganglioma following malignant lung metastasis. In addition, we identified an asymptomatic carrier of the SDHB mutation in this family.

Congenital fibrosarcoma with a novel complex 3-way translocation t(12;15;19) and unusual histologic features

Congenital mesenchymal tumors are diagnostically challenging as they are rare and may feature overlapping patterns between several benign, low-grade, and tumors of intermediate malignancy, including myofibromatosis, myofibroma/hemangiopericytoma, congenital fibrosarcoma, and inflammatory myofibroblastic tumor. Their immunophenotype is either silent or minimally expressive, and their ultrastructural features are generically consistent with "fibroblastic/myofibroblastic" differentiation. Cytogenetic analysis allows refined diagnoses, improved classifications, and bettering of our therapeutic armamentarium. However, genotype/phenotype correlations continue rendering novel findings that must be examined for their potential value in diagnosis and treatment. We describe a retroperitoneal congenital fibrosarcoma with an unusually bland histopathology and novel 3-way t(12;15;19) translocation involving chromosome bands 12p13.2, 15q25.3, and 19p13.1, associated with trisomies 8, 11, and 20. Fluorescence in situ hybridization showed one fusion signal in the normal chromosome 12p13.2 and break-apart 3'ETV6 and 5'ETV6 signals in the rearranged 12p13.2 and 15q25.3, respectively. The importance of molecular diagnosis and genotype-phenotype correlations is emphasized.

Congenital Ewing sarcoma in retroperitoneum with multiple metastases

A 7-day-old Japanese female showed the absence of spontaneous movement in her both legs. MRI revealed tumors in the retroperitoneum invading into the spinal canal, the left cerebral hemisphere and the right eyeball. Histological examination of retroperitoneal tumor revealed the sheets of undifferentiated small round cells with hyperchromatic nuclei and scanty cytoplasm. EWS-FLI1 fusion gene was detected by RT-PCR, indicating Ewing sarcoma. She received chemo-radiotherapy and survived for 2 years and 10 months despite the multiple metastases at initial presentation.

Establishment and Characterization of a Human Liposarcoma Cell Line (HTLS) from the Retroperitoneal Liposarcoma

A cell line designated HTLS was established from the retroperitoneal liposarcoma. The HTLS line showed stable proliferation without interruption for 2 years and subcultivated over 35 times. The cells were elongated fibrous and spindle in shape, and neoplastic and pleomorphic features. The multinucleated giant cells with fine cytoplasm were seen. The cells proliferated slowly and the population doubling time was about 90 hours. The chromosome number showed a wide distribution of aneuploidy, the mode was hyperdiploid range (51-52), and many marker chromosomes were observed. The cells were transplantable into the submucosa of immunesuppressed hamster's cheek pouch and produced liposarcoma, while were not transplantable into subcutis of nude mice

Benign retroperitoneal schwannoma presenting as colitis: A case report

We report a case of a patient presenting with clinical, radiological and endoscopic features of colitis due to a compressive left para-aortic mass. Total open surgical excision was performed, which resulted in complete resolution of colitis. Histopathology and immunohistochemistry revealed benign retroperitoneal schwannoma. These neural sheath tumors rarely occur in the retroperitoneum. They are usually asymptomatic but as they enlarge they may compress adjacent structures, which leads to a wide spectrum of non-specific symptoms, including lumbar pain, headache, secondary hypertension, abdominal pain and renal colicky pain. CT and MR findings show characteristic features, but none are specific. Schwannoma can be isolated sporadic lesions, or associated with schwannomatosis or neurofibromatosis type II (NF2). Although they vary in biological and clinical behavior, their presence is, in nearly every case, due to alterations or absence of the NF2 gene, which is involved in the growth regulation of Schwann cells. Both conditions were excluded by thorough mutation analysis. Diagnosis is based on histopathological examination and immunohistochemistry. Total excision is therapeutic and has a good prognosis. Schwannomatosis and NF2 should be excluded through clinical diagnostic criteria. Genetic testing of NF2 is probably not justified in the presence of a solitary retroperitoneal schwannoma.

Dedifferentiated Liposarcomas With Divergent Myosarcomatous Differentiation Developed in the Internal Trunk

Dedifferentiated liposarcoma (DLPS) is one of the most frequent sarcomas of the retroperitoneum and represents most undifferentiated sarcomas of the internal trunk. In about 5% cases, the dedifferentiated component is an heterologous sarcoma such as leiomyosarcoma or rhabdomyosarcoma. We reviewed a series of 65 sarcomas with a myogenic differentiation developed in the internal trunk for which initial diagnoses were leiomyosarcoma (37), rhabdomyosarcoma (6), malignant mesenchymoma (6), and DLPS (16). Immunostainings for MDM2, CDK4, alpha smooth actin, desmin, caldesmon, myogenin, c-kit, and progesterone receptor were performed. In 48 cases, the amplification status of MDM2 and CDK4 could be evaluated with quantitative polymerase chain reaction on paraffin-embedded tissues extracted DNAs. After review of the cases, final diagnoses were leiomyosarcoma (35), rhabdomyosarcomatous (20) or leiomyosarcomatous (7) DLPS, probable DLPS (2), and malignant mesenchymoma (1). DLPS were bigger tumors (median: 18.2 cm) than leiomyosarcomas (median: 12 cm). They had a lower 5-year recurrence-free survival than leiomyosarcomas (45% vs. 71%) but a higher 5-year metastasis-free survival (73% vs. 39%). There was no significant difference in overall survival (57% vs. 34%). Outcome of patients with a DLPS with a myosarcomatous component did not differ from conventional DLPS. In conclusion, most sarcomas with a rhabdomyosarcomatous differentiation occurring in the internal trunk of adults are DLPS. Moreover, DLPS with a myogenic component have a low metastatic potential, similar to conventional DLPS and significantly lower to the metastatic potential of leiomyosarcomas.

[Analysis of 13q14 chromosomal instability in soft tissue tumors by fluorescence in-situ hybridization]

OBJECTIVE

To investigate the genetic status of 13q and its role in the oncogenesis and progress of soft tissue tumors.

METHODS

Forty-one soft tissue tumors, including 9 benign tumors, 9 tumors of malignant potential and 23 sarcomas, were studied by fluorescence in-situ hybridization (FISH) using dual color probes. The probes were generated from BAC clones RP11-685I15, RP11-352N7 and RP11-505F3, corresponding to Rb, RFP2, KCNRG and KLF5 genes respectively.

RESULTS

Loss of heterozygosity (LOH) of RP11-685I15 were found in 8/41 cases, LOH of RP11-352N7 was seen in 4/41 cases and LOH of RP11-505F3 was present in 3/41 cases. LOH of all 3 loci were detected in 2 cases. LOH of RP11-61K9, an internal control locus, was detected in 2 cases. One case of malignant peripheral nerve sheath tumor showed amplification at all 3 loci. Amplification of RP11-505F3 was seen in another 2 cases.

CONCLUSIONS

A significant percentage of soft tissue tumors exhibited chromosomal instability, reflected by an increase of LOH at tumor-suppressing gene loci. The incidence of 13q abnormality was different in various types of soft tissue tumors, indicating that alterations of Rb, RFP2, KCNRG and KLF5 tumor suppressing genes may play diverse roles in different types of soft tissue tumor.

JUN oncogene amplification and overexpression block adipocytic differentiation in highly aggressive sarcomas

The human oncogene JUN encodes a component of the AP-1 complex and is consequently involved in a wide range of pivotal cellular processes, including cell proliferation, transformation, and apoptosis. Nevertheless, despite extensive analyses of its functions, it has never been directly involved in a human cancer. We demonstrate here that it is highly amplified and overexpressed in undifferentiated and aggressive human sarcomas, which are blocked at an early step of adipocyte differentiation. We confirm by cellular and xenograft mouse models recapitulating these sarcoma genetics that the failure to differentiate is dependent upon JUN amplification/overexpression.

Recognition of Li Fraumeni syndrome at diagnosis of a locally advanced extremity rhabdomyosarcoma

A contemporaneous presentation of a second breast cancer in a mother and an extremity rhabdomyosarcoma (RMS) in her daughter led to the diagnosis of the Li Fraumeni syndrome (LFS). Although the association between LFS and RMS in young patients is well recognised 1 there are no guidelines as to how this knowledge should influence the optimal management of these patients. After reviewing the literature about the natural history of the LFS 2, the incidence of second malignancy (SMN) in RMS survivors 3-6 and the management of extremity RMS 7-9, we are concerned that contemporary RMS treatment, combining non-mutilating surgery with chemoradiotherapy, may be associated with an excessive SMN risk in LFS patients with advanced RMS. We question whether treatment should be individualised and, where possible and acceptable to the family, measures such as amputation should be the considered to attain local control for LFS patients with RMS as this will avoid the need for local radiotherapy without compromising long-term function and quality of life 10.

[Unusual expression and molecular mechanisms of E-cadherin, beta-catenin in correlation with clinicopathologic parameters in neuroblastoma]

OBJECTIVE

To study the expression of E-cadherin and beta-catenin in neuroblastomas of various degrees of differentiation, and to investigate their molecular mechanisms in correlation with clinicopathologic parameters.

METHODS

Immunohistochemistry EnVision method was used to detect E-cadherin and beta-catenin expression in 90 paraffin-embedded tissue samples of neuroblastomas. The methylation status of CpG islands of E-cadherin promoter was investigated by MSP in 7 fresh tissue and 24 paraffin-embedded tissue samples. The mutation status of exon 3 of beta-catenin gene was studied by PCR in 7 fresh tissue samples. Statistical analysis of the data was performed by SPSS software.

RESULTS

E-cadherin and beta-catenin were abnormally expressed in neuroblastomas in general. The expression of beta-catenin in well-differentiated neuroblastoms was markedly higher (47/70, 67.1%) than that of the poorly differentiated tumors (8/20, 40.0%). There was a markedly decreased expression of both genes in tumors with lymph node metastasis than those without. Demethylation was seen in some regions of the promoter of E-cadherin in 31 cases of nuroblatomas. PCR of the exon 3 of beta-catenin followed by DNA sequencing demonstrated rearrangements and mutations in 7 cases, including 2 cases harboring identical point mutation at gene position 27184, leading to a T-->A alteration.

CONCLUSIONS

The abnormal over-expression of E-cadherin in neuroblastomas is independent of the methylation status of their promoter sequences. The abnormal expression of beta-catenin may be related to mutational changes at exon 3 of the gene.

Cytogenetic and molecular cytogenetic findings in dedifferentiated liposarcoma with neural-like whorling pattern and metaplastic bone formation

Dedifferentiated liposarcoma is a subtype of liposarcoma characterized by juxtaposition of well-differentiated liposarcoma with a nonadipocytic sarcoma. A peculiar form of dedifferentiated liposarcoma has been described, characterized by a nonlipogenic component with a neural-like whorling pattern of growth and metaplastic bone formation. We report the cytogenetic and molecular genetic findings of this peculiar form of dedifferentiation in a retroperitoneal tumor found in a 58-year-old female. The neoplasm had typical histologic findings and a complex karyotype characterized by several numeric and structural chromosomal abnormalities, including the presence of ring and giant rod chromosomes. Molecular cytogenetic studies found high levels of amplification of the MDM2 oncogene, consistent with the amplification of the 12q14 chromosome band, a cytogenetic abnormality commonly found in these tumors. These findings indicate that, despite its unique and peculiar morphologic features, this unusual type of dedifferentiated liposarcoma shares many of the cytogenetic features and molecular genetic abnormalities found in other forms of dedifferentiation. The specific cytogenetics and molecular determinants of these peculiar morphologic findings, however, remain unknown.

CGH evaluation of two de novo synchronous tumors in a child with a germline p53 mutation

We report the case of a child who developed two de novo synchronous tumors: an osteosarcoma and an embryonal rhabdomyosarcoma. The patient was determined to be a de novo carrier of a P53 germline mutation. Comparative genomic hybridization (CGH) analysis revealed that each of the neoplasms was characterized by a specific set of chromosomal imbalances and high-level amplification (HLA) regions. Our CGH findings provide evidence that cancer development is a cellular/organ specific event.

Cytogenetic and molecular genetic findings in dedifferentiated liposarcoma with neural-like whorling pattern and metaplastic bone formation

Dedifferentiated liposarcoma, a subtype of liposarcoma, is characterized by juxtaposition of well-differentiated liposarcoma with a nonadipocytic sarcoma. A peculiar form of dedifferentiated liposarcoma has been described, characterized by a nonlipogenic component with a neural-like whorling pattern of growth and metaplastic bone formation. We report the cytogenetic and molecular genetic findings of this peculiar form of dedifferentiation in a retroperitoneal tumor found in a 58-year-old woman. The neoplasm had the typical histologic findings and a complex karyotype characterized by several numeric and structural chromosome abnormalities, including the presence of ring and giant rod chromosomes. Molecular genetic studies found high levels of amplification of the MDM2 oncogene, consistent with the amplification of the 12q14 chromosome band, a cytogenetic abnormality commonly found in these tumors. These findings indicate that, despite its unique and peculiar morphologic features, this unusual type of dedifferentiated liposarcoma shares many of the cytogenetic and molecular genetic abnormalities found in other forms of dedifferentiation. However, the specific cytogenetic and molecular determinants of these peculiar morphologic findings remain unknown.

Determination of genomic damage in neuroblastic tumors by arbitrarily primed PCR: MYCN amplification as a marker for genomic instability in neuroblastomas

The aim of this study is to establish an estimation of the global genomic alteration in neuroblastic tumors (ganglioneuromas, ganglioneuroblastomas and neuroblastomas) and correlate them with different clinical parameters (age, sex, diagnosis, Shimada index, proliferation index, tumor location, and 1p and v-myc avian myelocitomatosis viral-related (MYCN) status) in order to find new molecular and/or prognostic markers for neuroblastoma. To assess the genomic damage in neuroblastic tumors, we used an arbitrarily primed PCR approach, a technique based on the reproducibility of band profiles obtained by a PCR with a low annealing temperature in its first cycles. Genomic damage was assessed by comparing band profiles of tumors and normal paired samples. Gains and losses in the intensity of the bands were computerized and referred to the total number of bands analyzed. We found a higher genomic damage fraction (GDF) in the female's group (U-Mann-Whitney, P = 0.025), but we could not find any association between GDF and tumor location, proliferation index, diagnosis or age of the patient. There was no relationship between 1p status and GDF, but tumors with MYCN amplification had a slightly higher GDF. MYCN amplification might in some way contribute to genomic instability of neuroblastomas.

The malignant potential of a succinate dehydrogenase subunit B germline mutation

Familial catecholamine secreting tumors have been associated with multiple endocrine neoplasia type 2, Von Hippel-Lindau disease and neurofibromatosis type 1. In the last years, mutations of genes encoding subunits B, C and D of the succinate dehydrogenase have been discovered as other causes of pheochromocytomas and paragangliomas. We diagnosed a malignant retroperitoneal paraganglioma in a 64-yr-old man with bone metastasis in 2001. Two years later a retroperitoneal benign paraganglioma was found and resected in his 32-yr-old daughter. Thus we diagnosed in this family a paraganglioma syndrome. We performed molecular genetic analyses of the genes SDHB, SDHC, and SDHD. We detected in the SDHB gene the mutation SDHB c. 558-3 C> G affecting the splice site of exon 5. In a second daughter the mutation was also detected, thorough clinical investigation revealed normal results. We conclude that the SDHB mutation predisposes to abdominal extra-adrenal and potential malignant pheochromocytoma with incomplete penetrance.

Cytogenetic confirmation of a gastrointestinal stromal tumor and ewing sarcoma/primitive neuroectodermal tumor in a single patient

We report a rare case in which two tumor entities, a gastrointestinal stromal tumor (GIST) and Ewing sarcoma/primitive neuroectodermal tumor (ES/PNET), with distinct cytogenetic features occurred in a single patient. The patient was a 72-year-old woman. The first tumor was a submucosal gastric tumor and was diagnosed as a low-risk group GIST based on morphological characteristics and the results of an immunohistochemical analysis for c-kit and CD34. Further cytogenetic analysis revealed that this tumor had a point mutation (D842V substitution) in exon 18 of the platelet-derived growth factor receptor alpha gene. The second tumor was found more than 4 years after the appearance of the first tumor. ES/PNET was highly suspected both morphologically and immunohistochemically, and the diagnosis was confirmed by the detection of an EWS rearrangement using a fluorescence in situ hybridization technique. Although the cytogenetic correlations of these two tumors are unclear, accurate histologic recognition is of clinical importance because the treatments for these two tumors differ.

Dedifferentiated liposarcoma with rhabdomyoblastic differentiation

Dedifferentiated areas of dedifferentiated liposarcoma (DDL) usually show malignant fibrous histiocytoma (MFH)- or fibrosarcoma-like features and lack any histologic signs of specific differentiation. However, some reports have demonstrated specific differentiation in these areas, with histologic features resembling those of rhabdomyosarcoma, leiomyosarcoma, and osteosarcoma. We report here a pathologic and genetic analysis of three cases of DDLs with rhabdomyosarcomatous areas. MFH- or fibrosarcoma-like areas of one primary DDL and two recurrent DDLs contained various amounts of rhabdomyoblasts, which were immunoreactive for desmin, myoglobin, muscle actin (HHF-35), and myogenin. An ultrastructural examination demonstrated rhabdomyoblasts with abundant cytoplasm containing thin and thick filaments and Z-bands. By real-time PCR, amplification of mdm2 and cdk4 was confirmed in both well-differentiated and dedifferentiated areas with rhabdomyoblasts of all cases. To our knowledge, only seven cases of DDLs with rhabdomyosarcomatous components have been reported, and furthermore, the genetic profiles of the rhabdomyosarcomatous components in DDLs have not been investigated. This study demonstrates that DDLs with rhabdomyosarcomatous areas have genetic alterations that are common to well-differentiated/dedifferentiated liposarcomas.

C-kit expression in dedifferentiated and well-differentiated liposarcomas; immunohistochemistry and genetic analysis

BACKGROUND

c-kit expression by immunohistochemistry has been utilized to identify cancer patients who can be treated with imatinib-mesylate. In gastrointestinal stromal tumors (GISTs), an activating mutation in c-kit predicts treatment response; its presence in other soft tissue tumors is unexplored.

MATERIALS AND METHODS

We evaluated seven cases of dedifferentiated liposarcomas (DDLS) and compared those with seven well-differentiated liposarcomas (WDLS). Immunohistochemical staining for c-kit was performed using a polyclonal antibody. Using PCR, exons 9, 10-11, 12-13 and 17 of c-kit were amplified and direct DNA sequencing performed.

RESULTS

Two out of 7 (30%) DDLS showed focal weak immunoreactivity with c-kit; no (0%) WDLS stained with c-kit. Seven out of 7 (100%) DDLS showed an allelic variation in exon 10, with a single base pair substitution (A >C) at codon 541; 3/7 (43%) WDLS showed the same change.

CONCLUSION

c-kit immunoreactivity did not correlate with the change in DNA sequence; DDLS showed a consistent allelic variation in c-kit that may have significant prognostic, diagnostic and therapeutic implications.

Monosomy 22 as a diagnostic aid in a case of late recurrence of adult granulosa cell tumor of the ovary

Cytogenetic analysis of a case of metastatic granulosa cell tumor recurring 21 years after oophorectomy revealed monosomy 22. This anomaly, typical of granulosa cell tumor, coupled with the pathologic and immunophenotypic findings assisted in establishing the proper diagnosis of this lesion in the absence of the original histopathologic slides.

Inflammatory malignant fibrous histiocytomas and dedifferentiated liposarcomas: histological review, genomic profile, andMDM2 andCDK4 status favour a single entity

Inflammatory malignant fibrous histiocytoma (inflammatory MFH) is a very rare tumour that occurs most often in the retroperitoneum. So far, it has been considered to be a special subtype of MFH. As it is now widely accepted that most retroperitoneal pleomorphic MFHs are dedifferentiated liposarcomas, the present study compared histological features, genomic profile (CGH analysis), and MDM2 and CDK4 status (immunohistochemistry, FISH, and quantitative PCR) in inflammatory MFHs from 12 patients and dedifferentiated liposarcomas that had an inflammatory MFH component from eight patients. Metaphase cytogenetic and FISH analyses were also performed on one inflammatory MFH. Histological review showed areas of well-differentiated liposarcoma in nine inflammatory MFHs. CGH analysis showed 12q13-15 amplification or gain in six of seven inflammatory MFHs and in seven of seven dedifferentiated liposarcomas. Immunohistochemistry showed positivity of tumour cells for MDM2 in every tumour in both groups and for CDK4 in ten and seven inflammatory MFHs and dedifferentiated liposarcomas, respectively. Metaphase cytogenetic and FISH analysis performed on one inflammatory MFH showed the presence of a supernumerary large marker chromosome and ring chromosome with high-level amplification of both MDM2 and CDK4 genes. FISH analysis on paraffin wax-embedded sections showed amplifications of MDM2 and CDK4 in seven of seven inflammatory MFHs and in seven of seven dedifferentiated liposarcomas. Quantitative PCR showed amplification of MDM2 in six and of CDK4 in seven of nine inflammatory MFHs. In conclusion, this study strongly suggests that most so-called inflammatory MFHs are dedifferentiated liposarcomas.

ASK1 (MAP3K5) as a potential therapeutic target in malignant fibrous histiocytomas with 12q14-q15 and 6q23 amplifications

Malignant fibrous histiocytomas (MFHs) are aggressive tumors without any definable line of differentiation. We recently demonstrated that about 20% of them are characterized by high-level amplifications of the 12q14-q15 chromosome region, associated with either 1p32 or 6q23 band amplification. This genetic finding, very similar to that in well-differentiated liposarcomas, strongly suggests that these tumors actually correspond to undifferentiated liposarcomas. It also suggests that the lack of differentiation could be the consequence of amplification of target genes localized in the 1p32 or 6q23 bands. We report here the characterization by array CGH of the 6q23 minimal region of amplification. Our findings demonstrate that amplification and overexpression of ASK1 (MAP3K5), a gene localized in the 6q23 band and encoding a mitogen-activated protein kinase kinase kinase of the JNK-MAPK signaling pathway, could inhibit the adipocytic differentiation process of the tumor cells. Treatment of a cell line with specific inhibitors of ASK1 protein resulted in the bypass of the differentiation block and induction of a strong adipocytic differentiation. These observations indicate that ASK1 is a target for new therapeutic management of these aggressive tumors.

Primary retroperitoneal teratomas: a review of the literature

Teratomas are uncommon neoplasms comprised of mixed dermal elements derived from the three germ cell layers. Historically, teratomas were attributed to demons, sexual misconduct, and abnormal fertilization. They attract attention because of their bizarre histology and gross appearance. While the majority of teratomas present congenitally in the sacrococcygeal region, within the ovaries of adolescent females and within the testes of young men, they have been identified throughout the body. Extragonadal teratomas tend to occur in midline structures as the anterior mediastinum, retroperitoneum, sacrococcygeal region, and pineal gland. Retroperitoneal teratomas represent only 1-11% of primary retroperitoneal tumors. Incidence is bimodal with peaks in the first 6 months of life and in early adulthood. Due to their location, they are usually identified only after they have grown to huge proportions. There is a 25% chance of malignancy. Surgical resection remains the mainstay of therapy and is required for definitive diagnosis. This article reviews the literature on the histopathology, classification, genetic abnormalities, and theories of origin of teratomas as well as the presentation, diagnosis, and management of retroperitoneal teratomas.

Surgical management of hereditary pheochromocytoma1 1No competing interests declared

BACKGROUND

Surgical treatment of hereditary pheochromocytoma remains controversial because of the need for lifelong corticosteroid therapy and the risk of Addisonian crisis associated with bilateral total adrenalectomy. We examined our large series of patients with hereditary pheochromocytoma to evaluate postsurgical outcomes, particularly in those who underwent cortical-sparing adrenalectomy.

STUDY DESIGN

We retrospectively reviewed the outcomes of all patients with histopathologic diagnoses of hereditary pheochromocytoma treated at our institution from 1962 to 2003. Familial disease was initially determined by pedigree analysis, genetic testing, or both for multiple endocrine neoplasia (MEN) types 1, 2A, or 2B; von Hippel-Lindau disease (VHL); neurofibromatosis type 1 (NF-1); or familial paraganglioma syndrome (FP).

RESULTS

Adrenal pheochromocytomas were present in 56 of 59 patients (95%): MEN2A (39), MEN2B (7), VHL (6), MEN1 (2), NF-1 (2). Paragangliomas (extraadrenal pheochromocytomas) were present in the remaining 3 of 59 patients (5%): FP (2) and NF-1 (1). Thirty-eight of 56 patients with pheochromocytomas had cumulative operations resulting in total or subtotal bilateral adrenalectomy. Acute adrenal insufficiency (Addisonian crisis) occurred in 4 of these 38 patients (11%). Cortical-sparing adrenalectomy was performed in 26 patients who underwent bilateral adrenal resection; 17 (65%) were corticosteroid independent at a median followup of 71 months. Recurrent pheochromocytoma developed in an adrenal remnant in 3 of 30 patients (10%) who underwent unilateral or bilateral cortical-sparing procedures. Metastatic disease did not develop in any patient with pheochromocytoma, but has occurred in two of three patients with paragangliomas.

CONCLUSIONS

Our data suggest that a cortical-sparing adrenalectomy can successfully avoid the need for corticosteroid replacement in the majority of patients who undergo a bilateral adrenalectomy. Long-term followup should include monitoring of the remnant gland for recurrent pheochromocytoma with yearly biochemical screening studies.

Distinct MDM2 and P14ARF expression and centrosome amplification in well-differentiated liposarcomas

Well-differentiated liposarcomas (WDLs) are common soft-tissue tumors in adults. They are characterized by large marker chromosomes and/or ring chromosomes containing 12q-derived sequences in which MDM2 is consistently amplified. WDLs are subdivided into two subtypes according to their karyotype. Type D cells exhibit a near-diploid karyotype, with very few or no chromosome changes. Type H cells exhibit a near-tetraploid karyotype and many structural changes. Expression of P14ARF, MDM2, and TP53 proteins was assayed in the two WDL subtypes to establish whether distinct expression profiles correlated with cell ploidy. Although a transcriptionally functional TP53 was present in most tumors independent of their karyotype, type H cells were characterized by high levels of P14ARF and MDM2 proteins. Although amplified within similar chromosome markers in type D tumors, MDM2 did not appear to be overexpressed. In addition, it was present as a C-terminal truncated protein, indicative of alternatively spliced variants of MDM2 mRNA. As the existence of karyotypically distinct tumors could result from alterations of the mitotic machinery, we investigated the centrosome behavior in the two WDL subtypes. Centrosome amplification occurred in WDL tumors types H and D independent of their ploidy status. Moreover, no functional centrosome difference was found between the two tumor subtypes.