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Biomedical subjects

G Amann

Publications and source records attributed to G Amann.

At least 37 records · Page 2Linked to original sources
PubMed2000

Emergence of an unusual bone marrow precursor B-cell population in fatal Shwachman-Diamond syndrome.

The Shwachman-Diamond syndrome (SDS) is a rare congenital disorder for which inheritance by an autosomal recessive trait has been suggested. Shwachman-Diamond syndrome is defined by exocrine pancreatic insufficiency combined with severe neutropenia. Moreover, SDS patients are at risk to develop neoplastic hematologic diseases. We describe 2 SDS-affected daughters of consanguine parents who were born 1 year apart, at 35 and 36 weeks of gestation, and who died at the age of 4 and 3.5 months, respectively, due to respiratory infections. Histologic bone marrow evaluation of the second-born child revealed a diffuse proliferation of immature B cells, which comprised 40% of the total cellularity. These cells were identified as precursor B cells by immunophenotyping studies (CD79a(+)/CD10(+)/CD20(-)/CD22(-)/CD34(-)/ terminal deoxynucleotidyl transferase(-)). Molecular determination of the immunoglobulin heavy-chain gene status did not reveal clonality. The emergence of this peculiar B-cell population was interpreted as a marked increase of hematogones. Although the clinical significance and the exact function of hematogones is still obscure, they may play a critical regenerative role in the regulation of hemopoiesis, but without malignant potential in SDS. Immunophenotyping and molecular studies, therefore, have potential value in the differential diagnosis of primary bone marrow failures. This report adds SDS to the spectrum of conditions in which a prominent number of hematogones may be observed.

Antigens, CD↗
PubMed1999

Angiosarcomas express mixed endothelial phenotypes of blood and lymphatic capillaries: podoplanin as a specific marker for lymphatic endothelium.

Angiosarcomas apparently derive from blood vessel endothelial cells; however, occasionally their histological features suggest mixed origin from blood and lymphatic endothelia. In the absence of specific positive markers for lymphatic endothelia the precise distinction between these components has not been possible. Here we provide evidence by light and electron microscopic immunohistochemistry that podoplanin, a approximately 38-kd membrane glycoprotein of podocytes, is specifically expressed in the endothelium of lymphatic capillaries, but not in the blood vasculature. In normal skin and kidney, podoplanin colocalized with vascular endothelial growth factor receptor-3, the only other lymphatic marker presently available. Complementary immunostaining of blood vessels was obtained with established endothelial markers (CD31, CD34, factor VIII-related antigen, and Ulex europaeus I lectin) as well as podocalyxin, another podocytic protein that is also localized in endothelia of blood vessels. Podoplanin specifically immunolabeled endothelia of benign tumorous lesions of undisputed lymphatic origin (lymphangiomas, hygromas) and was detected there as a 38-kd protein by immunoblotting. As paradigms of malignant vascular tumors, poorly differentiated (G3) common angiosarcomas (n = 8), epitheloid angiosarcomas (n = 3), and intestinal Kaposi's sarcomas (n = 5) were examined for their podoplanin content in relation to conventional endothelial markers. The relative number of tumor cells expressing podoplanin was estimated and, although the number of cases in this preliminary study was limited to 16, an apparent spectrum of podoplanin expression emerged that can be divided into a low-expression group in which 0-10% of tumor cells contained podoplanin, a moderate-expression group with 30-60% and a high-expression group with 70-100%. Ten of eleven angiosarcomas and all Kaposi's sarcomas showed mixed expression of both lymphatic and blood vascular endothelial phenotypes. By double labeling, most podoplanin-positive tumor cells coexpressed endothelial markers of blood vessels, whereas few tumor cells were positive for individual markers only. From these results we conclude that (1) podoplanin is a selective marker of lymphatic endothelium; (2) G3 angiosarcomas display a quantitative spectrum of podoplanin-expressing tumor cells; (3) in most angiosarcomas, a varying subset of tumor cells coexpresses podoplanin and endothelial markers of blood vessels; and (4) all endothelial cells of Kaposi's sarcomas expressed the lymphatic marker podoplanin.

Antigens, CD34↗
PubMed1999

Relation of neurological marker expression and EWS gene fusion types in MIC2/CD99-positive tumors of the Ewing family.

The Ewing family of tumors (EFT) is characterized by high MIC2/CD99 expression and specific EWS/ETS gene rearrangements, resulting in different chimeric transcripts. Further division into peripheral primitive neuroectodermal tumors and Ewing's sarcoma is still debated and, in the absence of distinct morphological parameters, has been based on the reactivity with neuroglial markers (NgM). We investigated 44 EFT in terms of a possible correlation between the type of EWS chimeric transcripts and reactivity with the following NgM: polyclonal and monoclonal neuron-specific enolase (NSE), S-100, chromogranin A, synaptophysin, Leu-7, glial fibrillary acid protein, and neurofilament. EWS/Fli1 fusion type 1 was detected in 30 of 44 and type 2 in 11 of 44 tumors. Three tumors, presenting with an uncommon morphology, carried rare chimeric transcripts. Our results indicate an association of lack of NgM staining with type 1 EWS/Fli1 translocations, found in 16 of 18 tumors with no NgM expression as detectable by any of the antibodies we applied. Using the monoclonal NSE antibody, 21 of 26 tumors without NgM staining expressed type 1 EWS/FLI1chimeric RNA, whereas in the groups with 1 or more and 2 or more NgM, only 9 of 17 and 1 of 5 tumors, respectively, carried type 1 EWS/Fli1 fusion transcripts. Despite this association of increased NgM expression with a non-type 1 EWS/Fli1 gene fusion, a strict correlation between the extent of NgM expression and certain EWS fusion types was not evident. This fortifies the concept to consider EFT as a spectrum of tumors and suggests the type of EWS fusion transcripts as one, but not the only parameter influencing the extent of differentiation.

Adolescent↗
PubMed1999

Elastofibroma dorsi. Study of two cases and magnetic resonance imaging findings.

Two cases of elastofibroma dorsi (one bilateral, one unilateral) in the periscapular and infrascapular region of two male patients are described. Magnetic resonance imaging revealed a tumorous mass of typical low signal intensity with interspersed areas of high signal intensity on T1 and T2 weighted spin echo sequences. In contrast to previous studies that reported mild enhancement within elastofibromas after administration of intravenous contrast agent, marked enhancement in one of two elastofibromas was found. This is considered to be atypical for benign lesions. After biopsy and histopathologic examination, an intended marginal resection was performed in both cases. Laboratory values, radiographs, and computed tomography may not be helpful in differentiating elastofibroma from malignant tumors. In addition to careful clinical investigation, magnetic resonance imaging is the method of choice leading to a presumptive diagnosis. Because marked enhancement on contrast agent images was observed, which is characteristic for malignant tumors, one should be aware that this feature does not exclude the presence of elastofibroma. Accurate diagnosis should be made preferably by biopsy and histopathologic evaluation before additional treatment is administered. Marginal resection is curative in patients with symptoms. Despite its low incidence, this pseudotumoral lesion should be known generally to differentiate it from malignant tumors and to avoid unnecessary wide or radical surgery.

Back↗
PubMed1999

[Podoplanin--a specific marker for lymphatic endothelium expressed in angiosarcoma].

AIMS: Angiosarcomas apparently derive from endothelia of the blood vasculature, however occasionally their histologic features suggest mixed origin from blood and lymphatic endothelia. In the absence of specific positive markers for lymphatic endothelia the precise distinction between these components was not possible so far. Here we provide evidence that podoplanin, a approximately 38 kD membrane glycoprotein of podocytes is a specific marker of lymphatic endothelium that was used to identify the relative fraction of tumor cells with lymphatic or blood vascular endothelial phenotype in vascular tumors. METHODS: Podoplanin was localized in normal human skin and kidney cortex by immunohistochemistry on paraffin sections, double immunofluorescence on frozen sections with PAL-E, immunoelectron microscopy and by immunoblotting. 45 vascular tumors (29 benign lesions, 11 angiosarcomas and 5 gastrointestinal Kaposi's sarcomas) were evaluated for podoplanin expression. Complementary staining was obtained with established endothelial markers (CD 31, CD 34, Factor VIII related antigen, UEA I) and with podocalyxin, another podocytic protein mainly present in endothelia of blood vessels. RESULTS: In human tissues podoplanin is specifically expressed in the endothelium of lymphatics, but not in blood vasculature or in hemangiomas. This expression is preserved in endothelia of all benign lymphatic tumorous lesions and all Kaposi's sarcomas examined. By contrast 10 out of 11 G3 angiosarcomas contained only variable fractions of podoplanin-expressing tumor cells. Most tumor cells coexpressed podoplanin and markers of blood vessel phenotype. CONCLUSIONS: (1) Podoplanin is a selective marker of lymphatic endothelium; (2) G3 angiosarcomas display a quantitative spectrum of podoplanin-expressing tumor cells; (3) In the majority of angiosarcomas tumor cells coexpress podoplanin and endothelial markers of blood vessels; (4) All endothelial cells of Kaposi's sarcomas expressed the lymphatic marker podoplanin.

Biomarkers↗
PubMed1998

Expression of the aryl hydrocarbon receptor (AhR) and the aryl hydrocarbon receptor nuclear translocator (ARNT) in fetal, benign hyperplastic, and malignant prostate.

BACKGROUND: Androgen-dependent tissue has been reported to be affected by chemical ligands of the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, which heterodimerizes with the aryl hydrocarbon receptor nuclear translocator protein (ARNT). METHODS: Fetal (n = 3), benign hyperplastic (BPH) (n = 10), and carcinomatous (CaP) (n = 19) prostate tissues were analyzed using immunohistochemistry. Western blot analysis was used to confirm the identity of the recognized proteins. RESULTS: Immunoblotting of enriched prostatic epithelial cells (EC) and stromal cells revealed constitutive expression of bands at around 110 kDa and 90 kDa, using anti-AhR and anti-ARNT, respectively. Immunohistology of the fetal specimens revealed heterogeneous cytoplasmic and nuclear AhR expression of immature EC and mesenchymal cells. Constitutive expression of AhR (primarily cytoplasmic) and ARNT (nuclear and cytoplasmic) by the majority of adult basal and secretory EC, CaP, and smooth muscle cells was confirmed in situ. The most intense anti-AhR/-ARNT reactivity was found on smooth muscle cells, followed by EC and fibrocytes. Secretory BPH-EC revealed significantly decreased AhR expression when compared to normal tissue segments. By contrast, anti-AhR reactivity was frequently increased in the more dedifferentiated tumor areas. CONCLUSIONS: These findings suggest that an undefined physiologic AhR ligand(s) as well as environmental factors may exert effects on EC and smooth muscle cells in the prostate through binding to these receptors.

Adult↗
PubMed1998

Predictive potential of testing for bone marrow involvement in Ewing tumor patients by RT-PCR: a preliminary evaluation.

EWS/ets-oncogene fusion transcripts can be detected in at least 98% of Ewing tumors [(ET) Ewing sarcoma and peripheral primitive neuroectodermal tumor] by reverse transcriptase-polymerase chain reaction (RT-PCR), thus confirming the histopathologic diagnosis. To detect minimal amounts of tumor cells in the bone marrow (BM), we used an RT-PCR assay with a high sensitivity, revealing one tumor cell in a background of 10(6) normal cells. We examined BM samples from 35 newly diagnosed ET patients (23 with localized and 12 with metastatic disease). At diagnosis, tumor cells in the BM were detected in 7/23 patients with localized disease (30%). Fifty percent of patients with isolated lung metastasis were RT-PCR positive (3/6), whereas 6/6 patients with bone metastases showed positive signals (100%). All patients with initial PCR positivity in the BM became negative during treatment. After a median follow-up of 30 months, relapses were observed in both groups of patients with localized disease (3/7 RT-PCR positive and 2/16 RT-PCR negative). The only recurrence in the group with isolated lung metastases occurred as progressive lung disease in 1 of the 2 RT-PCR-negative patients, whereas among the 6 patients with bone metastases 2 remain in complete remission. So far, RT-PCR screening for BM involvement did not allow prediction of early relapse in ET. To assess better the significance of this test in the evaluation of long-term prognosis and in monitoring the effectiveness of systemic therapy, long observation periods are warranted before it becomes a tool for treatment stratification.

Adolescent↗
PubMed1998

Immunoapheresis in paraneoplastic pemphigus.

BACKGROUND: Paraneoplastic pemphigus was first described in 1990 in 5 patients with extensive mucocutaneous erosions, a distinct set of autoantibodies, and underlying neoplasia. Since then, patients described have been middle-aged, have suffered from prognostically unfavorable malignant neoplasms, and have responded poorly to immunosuppressive agents. OBSERVATION: A 16-year-old boy was examined with extensive oral erosions, halitosis that interfered with his quality of life, and rapid weight loss. The suspected clinical diagnosis of paraneoplastic pemphigus was confirmed by histopathological, immunofluorescence, and biochemical (eg, immunoblotting and immunoprecipitation) findings as well as by the demonstration of an inflammatory myofibroblastic tumor of the left retroclavicular region. Despite administration of corticosteroids, followed by excision of the neoplasm, clinical symptoms improved only slightly, and autoantibody titers decreased only marginally. We therefore initiated an immunoapheresis regimen with the use of sheep anti-human-IgG bead-formed agarose gel (Sepharose; Pharmacia Biotech Comp, Vienna, Austria), which led to the disappearance of circulating autoantibodies and the patient's recovery. CONCLUSION: Immunoapheresis may represent a novel therapeutic option for patients with paraneoplastic pemphigus who show little improvement after curative treatment of their neoplasms.

Adolescent↗
PubMed1998

Expression of the small heat shock protein HSP 27 in developing human skin.

The 27 kDa heat shock protein (HSP 27) is expressed in keratinocytes of the upper epidermal layers, and recent evidence suggests that this protein is involved in the regulation of epidermal differentiation. The expression of HSP 27 was investigated in developing human skin by immunohistochemistry utilizing a specific monoclonal antibody. We used formalin-fixed, paraffin-embedded tissue of abdominal skin obtained from 34 human fetuses ranging between 13 and 30 weeks estimated gestational age (EGA). We found that HSP 27 is not expressed in keratinocytes until week 14 EGA. At this stage staining is observed in the periderm and the upper intermediate cells but not in hair germs. During further development, HSP 27 expression correlates with increasing epidermal differentiation, i.e. shedding of the periderm and beginning of keratinization. HSP 27 expression is confined to the upper cell layers and sparse basal cells. In hair follicles, HSP 27 can be detected in the innermost cell layer of the outer root sheath and in keratinocytes of the bulge identical to what is observed in adult skin. The hair papilla, matrix cells and sebaceous glands are negative for HSP 27 and remain so during further development. In eccrine sweat glands of the 24th week EGA, HSP 27 is confined to the superficial cell layer of the sweat ducts. In the present report we demonstrate differentiation-related expression of HSP 27 in developing human skin. Further in vitro studies will address the molecular function of HSP 27 in epidermal differentiation and development.

Eccrine Glands↗
PubMed1998

Deficiency of laryngeal collagen type II in an infant with respiratory problems.

A dysmorphic infant is described who presented with laryngeal collapse leading to intubation and respiratory problems that were assigned clinically to the Sussman syndrome. The baby had repeated episodes of respiratory distress necessitating assisted ventilation. At 6 months old, uvulopharyngopalatotomy was done to enlarge the supraglottic airway without any benefit. Surgical reduction of the tongue and cricoid splitting did not ameliorate the respiratory distress; repeated extubation attempts failed with the baby developing stridor, respiratory distress, and episodes of cardiac arrest. At 10 months old he developed seizures and computed tomography showed diffuse cerebral atrophy consisted with hypoxic-ischaemic damage. He died at 17 months old. Western blots using antibodies against collagen alpha 1 (II) showed an absence of collagen type II in laryngeal tissue, which may explain the laryngeal collapse and impaired respiratory functions.

Blotting, Western↗
PubMed1998

Cellular localization of insulin-like growth factor II mRNA in the human fetus and the placenta: detection with a digoxigenin-labeled cRNA probe and immunocytochemistry.

IGF-II plays a major role in the regulation of human fetal growth and development. However, more extensive information on the cellular sites of IGF-II synthesis in the fetus would provide more insight into its role in fetal organogenesis. Thus we have determined the sites of IGF-II synthesis in 18-26-wk gestation human fetal tissues using in situ hybridization with a digoxigenin-labeled cRNA probe to localize IGF-II mRNA in fetal liver, kidney, adrenal gland, cerebral cortex, costal cartilage, skeletal muscle, and lung, and in placental tissue. In human fetal tissues it has to date been impossible to clearly assign IGF-II mRNA to epithelial cells of entodermal origin. Besides their already known localization in cell matrix and a variety of mesodermal cell types, strong IGF-II mRNA-positive signals were detected in epithelial cells in the liver (hepatocytes), bronchial and bronchiolar epithelium, undifferentiated renal tubular epithelium, mature glomerular epithelium, pelvic urothelium, and adrenal epithelial cells of the zona persistens. To identify the cellular location of immunoreactive IGF-II, we also performed immunocytochemical studies in tissues of the same fetuses. Every tissue studied except the cerebral cortex contained immunoreactive cells; however, immunostaining was generally weaker than in situ hybridization signals. Our data show that the distribution of IGF-II in human fetal tissue is much more widespread than hitherto thought. A digoxigenin-labeled detection system for IGF-II is more capable of detecting the cellular expression pattern of IGF-II than radioactive probes and is suitable for analysis of routinely prepared paraffin-embedded material.

Abortion, Induced↗
PubMed1997

Neuroblastoma screening in infants postponed after the sixth month of age: a trial to reduce "overdiagnosis" and to detect cases with "unfavorable" biologic features.

BACKGROUND: Encouraged by Japanese reports of the benefits of screening 6 month-old infants for neuroblastoma, a neuroblastoma screening program was introduced in Austria in 1991. However, because of concerns related to "overdiagnosis" by screening at this age, the screening test was performed at a later age. METHODS: From March 1991 to February 1995 neuroblastoma screening was performed on filter paper urine specimens in 100,043 Austrian infants (median age 8.5 months). Primary analysis of urine catecholamines (vanillylmandelic acid and homovanillic acid was performed by use of an E1A method. Questionable or positive results were confirmed by high performance liquid chromatography (HPLC). A double retest was requested following a positive HPLC result. RESULTS: Twenty-one infants were admitted to a hospital following repeatedly elevated values of vanillymandelic acid (VMA) and/or homovanillic acid (HVA). Eleven infants were found to have neuroblastoma (three stage 1, four stage 2B, four stage 3). Treatment consisted of surgery alone with total or subtotal resection in eight cases, surgery and chemotherapy in two cases, and chemotherapy alone in one case. Biologic features were assessed in all tumors excluding ploidy in one case. The majority of the tumors analyzed were near-triploid (9/10), however, two tumors revealed N-myc amplification. CONCLUSIONS: Our results demonstrate that stage distribution and biologic features of neuroblastomas diagnosed by screening at 8.5 months are different from the results of screening at 6 months. Furthermore, the detection of one neuroblastoma among 9,100 screened infants is significantly lower than the incidence of the Japanese screening program. Our results suggest that screening at an age of 7 to 10 months reduces overdiagnosis and may be of more benefit than earlier screening.

Age Factors↗
PubMed1997

Arginine reduces kidney collagen accumulation, cross-linking, lipid peroxidation, glycoxidation, kidney weight and albuminuria in the diabetic kk mouse.

In diabetic nephropathy a major current concept for pathogenesis is increased collagen accumulation in the glomerulus by increased collagen synthesis and decreased degradation. In the present study, we tested the hypothesis whether arginine is able to influence kidney lipid peroxidation, glycoxidation, collagen accumulation, glucose-mediated cross-linking, hydroxy radical attack, protein oxidation, nitric oxide formation and albuminuria in the diabetic kk mouse. Ten diabetic kk mice were given arginine 50 mg/kg body weight, 10 diabetic kk mice were not treated and used as negative controls and 10 kk mice were kept as healthy controls. Our results show that oral administration of low-dose arginine reduces kidney collagen accumulation as reflected by kidney hydroxyproline, cross-linking as reflected by pentosidine, lipid peroxidation, glycoxidation as reflected by carboxymethyl lysine, kidney weight and albuminuria in the diabetic kk mouse. Albuminuria in untreated animals was closely correlated with lipid peroxidation. Our results in the spontaneously diabetic kk mouse representing type 2 diabetes mellitus therefore confirm and extend recent findings of collagen reduction by arginine in a different animal model. The mechanism of reducing proteinuria can be assigned to the blocking of lipid peroxidation products by L-arginine.

Albuminuria↗
PubMed1997

Kynurenic acid and kynurenine aminotransferase in heart.

Kynurenic acid (KYNA) is a tryptophan metabolite and represents the only known endogenous compound acting as an antagonist to excitatory amino acid receptors in the mammalian CNS. Blocking of these receptors in CNS by KYNA affects cardiac function. As it is not known whether human heart is able to synthesize this neuromodulatory amino acid, we investigated the biosynthesizing enzyme of kynurenine aminotransferase (KAT) in the human heart and compared the activity with that of the human brain. The activities of heart and brain KATs were assayed by the conversion of L-kynurenine (L-KYN) to KYNA and quantitated by HPLC with fluorescence detection. Using either pyruvate or 2-oxoglutarate as cosubstrates, heart KAT was found to have a shallow pH optimum between 8 and 9. Highest heart KAT activity was seen in the presence of 2-oxoglutarate, followed by pyruvate. 2-oxoadipate, and 2-oxoisocaproate. Kinetic analyses, performed at pH 8.5, and using various concentrations of L-KYN (from 0.125 to 22.8 mM) in the presence of 2-oxoglutarate (1 and 5 mM) or pyruvate (5 mM) revealed apparent K(m) values in the millimolar range, for L-KYN 1.5, 27, and 20 mM, respectively. Heart KAT activities were compared with those in human brain KAT I and KAT II showing different pH optima 7.4 and 9.6, respectively. In contrast to brain KAT I, heart KAT activity was not inhibited by an excess of 2 mM L-tryptophan, L-glutamine, or L-phenylalanine at pH 9.6, as well as at pH 8 or 7.4. Our study demonstrates that human heart is capable of synthesizing KYNA from low concentrations of L-KYN selectively. A shallow pH optimum of KAT activity, i.e. between 8.0 and 9.0, pronounced 2-oxoacid specificity, and a lack of sensitivity to inhibition by L-glutamine, L-phenylalanine, and L-tryptophan indicate that the heart KAT system displays enzymatic characteristics different from those of human brain KAT I or KAT II. Fluctuation of L-KYN and 2-oxoacid levels may markedly influence the KYNA synthesis and subsequent KYNA effect on cardiac activity. KYNA synthesis in the human heart suggests a neurophysiologic role. Our studies from the basis for purification and further characterization of KAT protein in human heart as well as for physiologic studies.

Adolescent↗
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

Mobilization of tumour cells during biopsy in an infant with Ewing sarcoma.

UNLABELLED: Ewing sarcoma and the closely related peripheral primitive neuroectodermal tumour, recently referred to as Ewing tumour (ET), are characterised by unique gene rearrangements on chromosome 22. The breakpoints have been cloned and shown to fuse the Ewing sarcoma gene to one of two closely related ETS proto-oncogens, FLI-1 or ERG, which reside on chromosomes 11 and 21, respectively. The rearrangement results in the expression of specific hybrid transcripts which can be detected with high sensitivity by the reverse transcriptase polymerase chain reaction technique (RT-PCR) in primary tumours, blood and bone marrow. We report on a 7-month-old boy with a pelvic Ewing sarcoma in whom circulating tumour cells were identified in the peripheral blood during open tumour biopsy by RT-PCR. However, before and 6 days after surgery no tumour cells could be detected in the peripheral blood. CONCLUSION: The application of RT-PCR to monitor shedding of tumour cells during surgical intervention will help to evaluate if open biopsy potentially contributes to metastatic tumour cell spread.

Base Sequence↗