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Detection of chromosomal regions showing differential gene expression in human skeletal muscle and in alveolar rhabdomyosarcoma.

BACKGROUND: Rhabdomyosarcoma is a relatively common tumour of the soft tissue, probably due to regulatory disruption of growth and differentiation of skeletal muscle stem cells. Identification of genes differentially expressed in normal skeletal muscle and in rhabdomyosarcoma may help in understanding mechanisms of tumour development, in discovering diagnostic and prognostic markers and in identifying novel targets for drug therapy. RESULTS: A Perl-code web client was developed to automatically obtain genome map positions of large sets of genes. The software, based on automatic search on Human Genome Browser by sequence alignment, only requires availability of a single transcribed sequence for each gene. In this way, we obtained tissue-specific chromosomal maps of genes expressed in rhabdomyosarcoma or skeletal muscle. Subsequently, Perl software was developed to calculate gene density along chromosomes, by using a sliding window. Thirty-three chromosomal regions harbouring genes mostly expressed in rhabdomyosarcoma were identified. Similarly, 48 chromosomal regions were detected including genes possibly related to function of differentiated skeletal muscle, but silenced in rhabdomyosarcoma. CONCLUSION: In this study we developed a method and the associated software for the comparative analysis of genomic expression in tissues and we identified chromosomal segments showing differential gene expression in human skeletal muscle and in alveolar rhabdomyosarcoma, appearing as candidate regions for harbouring genes involved in origin of alveolar rhabdomyosarcoma representing possible targets for drug treatment and/or development of tumor markers.

Chromosome Mapping↗

Rhabdomyosarcomas in adults and children: an update.

CONTEXT: Rhabdomyosarcomas comprise a relatively common diagnostic entity among childhood cancers and a relatively rare one among adult tumors. They may possess a variety of histologies that generally differ among age groups. These lesions appear to be separate biologic entities as well as morphologic categories, with embryonal tumors having genetic lesions related to loss of heterozygosity and aberrant parental imprinting, alveolar tumors containing genetic fusions between PAX and forkhead genes, and pleomorphic tumors showing an accumulation of genetic lesions similar to other adult high-grade sarcomas. OBJECTIVE: To present guidelines for diagnosis of rhabdomyosarcoma and recent finding concerning the biology and classification of these lesions. DATA SOURCES: Review of recent and older published literature and distillation of the authors' experience. CONCLUSIONS: Infants and young children tend to have embryonal rhabdomyosarcomas, adolescents and young adults tend to have alveolar rhabdomyosarcomas, and older adults tend to have pleomorphic rhabdomyosarcomas, although there is some overlap. Newer rare entities, including spindle cell rhabdomyosarcoma and sclerosing rhabdomyosarcoma, have been described in children and adults. Fusion-positive tumors have a distinct molecular signature with downstream activation of a number of myogenic and tumorigenic factors. Genetic testing may be successfully used for diagnosis and may guide therapy in future clinical trials. Differential diagnosis has become simpler than in previous years, because of use of myogenic factors in immunohistochemistry, but classification based solely on histologic features remains challenging.

Adult↗

Rhabdomyosarcoma.

In children and young adults, rhabdomyosarcoma occurs with a frequency that is equal to or greater than that of all the other forms of soft-tissue sarcoma combined. Although the responsiveness of rhabdomyosarcoma to chemotherapy varies greatly among tumors with different primary sites and with different histologic features, the overall results of chemotherapy have been more impressive in rhabdomyosarcoma than in any other form of soft-tissue sarcoma. Rhabdomyosarcomas occur in almost all sites and age groups. Those that occur in trunk and extremity sites have an unusually high instance of alveolar or undifferentiated histologic features and are more common in older children and young adults. Although they constitute only one third of all patients with rhabdomyosarcoma, tumors that are primary in trunk and extremity sites present some of the most difficult therapeutic problems in the management of all patients with this tumor. The ability to accomplish an initial complete local tumor excision still represents a major factor in survival. Early reexcision in the case of incompletely excised tumors with small volumes of residual tumor is effective when feasible. Local control of rhabdomyosarcoma can be achieved by high-dose irradiation and frequently by lower-dose irradiation when given in conjunction with chemotherapy. Second-look surgery is an accurate predictor of outcome, and late excision of residual tumor after chemotherapy-radiation therapy regimens may influence outcome. A regimen of vincristine, actinomycin-D, and cyclophosphamide given as a "pulse", with or without Adriamycin (doxorubicin), is the standard chemotherapy with cisplatin, etoposide, melphalan, and other agents now under study in trials of the Intergroup Rhabdomyosarcoma Study.

Adult↗

Upstream CpG island methylation of the PAX3 gene in human rhabdomyosarcomas.

BACKGROUND: Adult tumors can be characterized by hypermethylation of CpG islands associated with 5'-upstream and coding regions of specific genes. This hypermethylation can also be part of the aging process. In contrast, much less is known about gene hypermethylation in childhood cancers, where methylation changes are not part of the aging process but likely represent developmental dysregulation. PAX3 is an important gene in muscle development and muscle-producing neoplasms such as rhabdomyosarcomas. PROCEDURES: We examined the methylation status of a PAX3 5'-CpG island in rhabdomyosarcoma subtypes and in normal fetal skeletal muscle. PAX3 methylation was analyzed in 15 embryonal rhabdomyosarcomas, 12 alveolar rhabdomyosarcomas, and in six normal skeletal muscle samples, using semi-quantitative PCR analysis of DNA digested with methyl-sensitive restriction enzymes. RESULTS: The CpG island in the upstream region of the human PAX3 gene was hypermethylated in the majority of ERMS examined (13 of 15 tumors, mean of 52% methylation), whereas most ARMS (9 of 12 tumors) and all normal muscle samples showed relative hypomethylation (both 18% mean methylation). Various CpG sites differ in contribution to overall PAX3 CpG island methylation, with methylation at a HaeII site being inversely correlated with PAX3 expression. CONCLUSIONS: PAX3 CpG island methylation appears to distinguish embryonal subtype of rhabdomyosarcoma from alveolar, and methylation at certain sites within this CpG island is inversely correlated with PAX3 expression. In addition to exemplifying developmental dysregulation, methylation of PAX3 has potential in the development of an epigenetic profile for the diagnosis of rhabdomyosarcoma.

Child↗

Childhood rhabdomyosarcoma in Ibadan, Nigeria: 1984-2003.

BACKGROUND: Rhabdomyosarcoma is the most common soft tissue sarcoma in children under 15 years of age. There is, however, a paucity of reports on the pattern of its occurrence in Nigeria and other parts of Africa. AIM: To describe the pattern of childhood rhabdomyosarcoma in Ibadan with respect to demography, morphology and tumour site. METHODS: This retrospective study was based on data obtained from the Ibadan cancer registry, College of Medicine, University of Ibadan. All histologically confirmed cases of rhabdomyosarcoma in children under 15 years of age seen at the University College Hospital Ibadan between 1984 and 2003 were included. Information obtained includes age, gender, morphology and sites of the tumours. RESULTS: Ninety-one children were seen with a male:female ratio of 1.5:1. Ages ranged from <1 to 14 years with a mean (SD) of 6.2 (4.1) years. The embryonal variant was the most common histological subtype (61.5%). Other subtypes were alveolar (13.2%), pleomorphic (4.4%) and rhabdomyosarcoma 'not otherwise specified' (20.9%). The majority (50.6%) of tumours were in the head and neck region and the common primary sites were soft tissue of the head, face (24.2%) and orbit (14.3%). Other sites included soft tissue of the pelvis (11.0%), genito-urinary tract (9.9%) and abdomen (9.9%). CONCLUSION: The pattern of rhabdomyosarcoma in Nigeria is similar to that in the United States and Europe, except for the rarity of parameningeal sites and extremities. There is a need for larger descriptive studies on childhood rhabdomyosarcoma in Africa.

Adolescent↗

Methylation alterations of the MyoD1 upstream region are predictive of subclassification of human rhabdomyosarcomas.

MyoD1 expression is a distinguishing characteristic of rhabdomyosarcoma. In this study, distinct methylation alterations were identified in the 5' flanking region of the MyoD1 gene from the two major subtypes, ie, alveolar and embryonal rhabdomyosarcoma. The MyoD1 methylation patterns of 26 rhabdomyosarcomas were compared with that of normal skeletal muscle and nonmuscle specimens by Southern blot analysis using methylation-sensitive restriction enzymes HhaI and HpaII. A 5-kb region immediately upstream of the MyoD1 coding sequence was found to be methylated in adult muscle and all nonmuscle tissues tested. The MyoD1 upstream region was unmethylated in the majority of the alveolar rhabdomyosarcomas (13 of 15, 87%) examined in this study. In contrast, 10 of 11 (91%) embryonal rhabdomyosarcomas showed a methylation pattern that was also observed in fetal muscle cells, in which the CpG sites in the MyoD1 upstream region were partially methylated. Our data suggest that the methylation status of the MyoD1 upstream CpG sites may be related to rhabdomyosarcoma tumorigenesis and may have valuable implications for its differential diagnosis.

Adolescent↗

ALK protein expression in rhabdomyosarcomas.

AIMS: The ALK p80 chimeric protein is thought to be up-regulated as a result of the t(2;5) as classically seen in anaplastic large cell lymphoma. However, rhabdomyosarcomas (in particular, the alveolar subtype) have also been noted to show expression of this protein. This study set out to examine ALK expression in a large number of rhabdomyosarcomas. METHODS AND RESULTS: Eighty-three cases of rhabdomyosarcomas and 16 cases of malignant mixed müllerian tumours with a rhabdomyosarcomatous component were retrieved from the archives of the Department of Anatomical Pathology for the period 1983-2001. The sections were stained with polyclonal ALK antibody. There were 52 male and 30 female patients. In one case, the gender of the patient was not indicated. The ages ranged from 1 week to 77 years. The most common site was the head and neck region, followed by the pelvis and extremities. Thirty-one cases were of the alveolar subtype while 40 cases were embryonal. There were four mixed embryonal/alveolar, six pleomorphic and two unclassifiable rhabdomyosarcomas. Fourteen of the 31 (45%) alveolar rhabdomyosarcomas stained positively for the ALK protein, while only six of the 40 embryonal (15%) cases showed positivity. One case each of the mixed embryonal/alveolar, pleomorphic and unclassified cases was also immunopositive. The rhabdomyosarcomatous component in the malignant mixed müllerian tumours was positive in four of the 16 cases. CONCLUSION: We conclude that a proportion of alveolar rhabdomyosarcomas (in particular) exhibit ALK protein expression. However, ALK expression is not restricted to this subtype. An extension of this study is to determine if this over-expression is as a result of the t(2;5) translocation.

Adolescent↗

Expression of interleukin 15 (IL-15) in human rhabdomyosarcoma, osteosarcoma and Ewing's sarcoma.

Interleukin 15 (IL-15) is a recently discovered cytokine that stimulates lymphocyte proliferation and migration via a trimeric receptor sharing the beta and gamma signal transducing chains with the IL-2 receptor. IL-15 is typically produced by normal cells that do not release IL-2, but little information is currently available on human tumors. To assess whether human musculo-skeletal sarcomas produce IL-15, we analyzed surgical specimens and cell lines obtained from rhabdomyosarcoma, osteosarcoma and Ewing's sarcoma. IL-15 mRNA was present in 9/9 surgical specimens (3 Ewing's sarcomas, 5 osteosarcomas and 1 rhabdomyosarcoma). The analysis of a panel of cell lines (7 derived from Ewing's sarcoma, 12 from osteosarcoma and 5 from rhabdomyosarcoma) showed that all rhabdomyosarcoma and osteosarcoma cell lines expressed IL-15 mRNA at levels ranging from low to high, while Ewing's sarcoma cells contained little or no IL-15 message. ELISA assays showed IL-15 release in a subset of rhabdomyosarcomas and osteosarcomas, but not in Ewing's sarcoma. The highest production of IL-15, in the picogram/ml range, was found in rhabdomyosarcoma cell lines RH30 and RD.

Enzyme-Linked Immunosorbent Assay↗

Production of stem cell factor and expression of c-kit in human rhabdomyosarcoma cells: lack of autocrine growth modulation.

Human rhabdomyosarcoma cells produce autocrine and paracrine growth factors that can sustain their growth and malignancy. Here we report constitutive production of stem cell factor (SCF) by 5 of 5 human rhabdomyosarcoma cell lines both of alveolar and embryonal histotype. SCF production, ranging from 30 to 162 pg/ml, was independent from the degree of myogenic differentiation and was not modulated by exogenous addition of retinoic acid (RA) or tumor necrosis factor-alpha (TNF-alpha). Four of 5 rhabdomyosarcoma cell lines expressed the mRNA for SCF receptor c-kit, while the 5th cell line became weakly positive for c-kit mRNA only after stimulation with retinoic acid. On the cell surface, c-kit protein was detectable at very low levels in only 1 of 5 rhabdomyosarcoma cell lines and was not up-regulated by RA or TNF-alpha. Addition of anti-c-kit and anti-SCF blocking antibodies, or of exogenous SCF did not alter the in vitro growth ability of rhabdomyosarcoma cells. In conclusion, our data show that rhabdomyosarcoma cells produce consistent amounts of SCF but did not demonstrate autocrine growth modulation. SCF secretion may thus have a paracrine, rather than an autocrine activity in this tumor.

Autocrine Communication↗

A phase II trial of ifosfamide in previously untreated children and adolescents with unresectable rhabdomyosarcoma.

BACKGROUND: Children and adolescents with unresectable rhabdomyosarcoma fare poorly when treated with contemporary chemotherapeutic regimens. Evaluation of newly developed agents in these patients is important to improve their outcome. Based on a preclinical rhabdomyosarcoma xenograft model that accurately predicted the activity of new agents, the safety and efficacy of ifosfamide was evaluated as part of a Phase II clinical trial in previously untreated children with unresectable rhabdomyosarcoma. METHODS: Twenty-two children and adolescents (median age, 9 years) with newly diagnosed unresectable rhabdomyosarcoma (Intergroup Rhabdomyosarcoma Study Group III [n = 15] or IV [n = 7]) received two courses of ifosfamide at a dose of 1.6 g/m2 intravenously for 5 days over a 6-week period. Then the patients were evaluated for response, and additional treatment with surgery, radiation therapy, and multiagent chemotherapy (vincristine, cyclophosphamide, dactinomycin, and doxorubicin) was administered. RESULTS: Nineteen of 22 patients (86%) had a partial response to ifosfamide given as a single agent. No complete responses to this agent alone were observed. After administration of additional chemotherapy and local control measures (radiation therapy and surgery), the estimated proportion of patients surviving progression-free at 2 years was 63% (95% confidence interval, 37-80%). Ifosfamide was tolerated well; the most frequent toxicity was nondose-limiting myelosuppression. Transient mild renal toxicity infrequently was observed, and no central nervous system toxicity occurred in this group of patients. CONCLUSIONS: Ifosfamide appears to have significant clinical activity in untreated patients with unresectable rhabdomyosarcomas. These findings provide an accurate estimate of the response rate to single-agent ifosfamide in this group of previously untreated patients and thus provide a foundation for its rational incorporation into multiagent clinical trials. In addition, the potential benefits of this type of new drug development were demonstrated.

Adolescent↗

Prognostic factors in head and neck rhabdomyosarcoma.

BACKGROUND: Rhabdomyosarcoma comprises less than 1% of all head and neck cancer. The purpose of our study is to review our institutional experience in this disease and to identify possible prognostic factors for patients with head and neck rhabdomyosarcoma. METHODS: One hundred forty patients with rhabdomyosarcoma were identified from 1955-1999 within the tumor registry. Of these cases, 49 (35%) were noted to be primary head and neck rhabdomyosarcomas. Retrospective chart reviews were completed to obtain the following data: age, gender, site, tumor size, histologic findings, Intergroup Rhabdomyosarcoma Study Group, treatment, local control, and survival. RESULTS: The 5-year overall survival and local control rates were 60% +/- 14% and 70% +/- 14%, respectively. Tumor size < or =5 cm (p =.014) and age < or =11 years (p =.036) were predictive of improved survival, whereas age < or =11 years was predictive of improved local control (p =.006). Children < or =11 years with a < or =5-cm tumor have the best overall survival, whereas patients >11 years with a tumor >5 cm have the worst survival. The 5-year survival was intermediate for children < or =11 years with a >5-cm tumor and patients >11 years with a < or =5-cm tumor. Radiotherapy treatment duration < or =45 days in group III disease was associated with improved overall survival but not local control. For the six patients with group I or II disease, who did not receive initial chemotherapy, five had relapses at the primary and/or distant sites. CONCLUSIONS: Improvement in outcome was obtained with multimodality treatment regimens for head and neck rhabdomyosarcoma. Both tumor size and age of patient were found to influence survival.

Adolescent↗

Overexpression of insulin-like growth factor binding protein-6 inhibits rhabdomyosarcoma growth in vivo.

Rhabdomyosarcoma is the most common soft-tissue sarcoma of childhood. Rhabdomyosarcoma cell lines overexpress insulin-like growth factor-II (IGF-II), an autocrine growth factor that is inhibited by insulin-like growth factor binding protein-6 (IGFBP-6). IGFBP-6 is associated with myoblast quiescence, and expression in rhabdomyosarcoma cells is low. The effect of IGFBP-6 on 2 rhabdomyosarcoma cell lines, RD and Rh30, was studied. IGFBP-6 inhibited anchorage-dependent growth of RD and Rh30 cells in a dose-dependent manner (p < 0.0001). IGFBP-6 also inhibited anchorage-independent growth of RD cells in soft agar in a dose-dependent manner (p < 0.01). Anchorage-independent growth of RD cells on polyhydroxyethylmethacrylate-coated plates was decreased to a minimum of 48% of control after treatment with IGFBP-6 (p < 0.001). In this system, IGFBP-6 increased apoptosis 4-fold (p < 0.001). IGF-II partially reversed the IGFBP-6-induced decrease in growth and increase in apoptosis. Rh30 cells were stably transfected with an IGFBP-6 cDNA and subcutaneous xenografts established in BALB/c nude mice. After 18 days, sizes of 2 independent clones of IGFBP-6-overexpressing Rh30 cells were reduced to 12% and 26% of vector control-transfected tumors (p = 0.0006 and 0.002, respectively). IGFBP-6 therefore inhibits proliferation and promotes apoptosis of rhabdomyosarcoma in vitro and dramatically inhibits xenograft growth in vivo, at least in part by inhibiting IGF-II. Low expression of IGFBP-6 may therefore contribute to rhabdomyosarcoma growth and metastasis.

Animals↗

Rhabdomyosarcoma in children: a histological and immunohistochemical study of 59 cases.

Recent studies have suggested that rhabdomyosarcoma can be divided into favourable and unfavourable histology groups. Those subtypes comprising the unfavourable histology group are alveolar, monomorphous round cell and anaplastic rhabdomyosarcoma, with a favourable histology group of embryonal rhabdomyosarcomas. An immunohistological study was undertaken on 59 childhood rhabdomyosarcomas, using antisera to keratin, S100 protein, vimentin, desmin, myoglobin, and troponin T. Our results suggest that desmin is the single most useful antibody in the diagnosis of rhabdomyosarcoma and was expressed in all our cases. The expression of troponin T in the majority of embryonal rhabdomyosarcomas but not in the other histological types has prognostic implications.

Child↗

Sclerosing rhabdomyosarcoma in childhood: case report and review of the literature.

Rhabdomyosarcoma is the most common soft tissue malignancy in children but is rare in adults. The latest World Health Organization classification of soft tissue tumors recognizes embryonal, alveolar, and pleomorphic rhabdomyosarcomas. More recently, a sclerosing variant of rhabdomyosarcoma has been recognized and reported in seven adult patients. We describe a pediatric case of sclerosing rhabdomyosarcoma presenting as a sacral mass in a 3-year-old girl. Morphologically, the tumor showed a prominent sclerosing hyaline matrix and demonstrated pseudovascular and microalveolar architectural foci. Focal positivity was seen with desmin, smooth muscle actin, and myogenin. MyoD1 showed uniform diffuse nuclear staining. Fusion transcripts were not demonstrated by reverse transcriptase-polymerase chain reaction analysis. The histology, immunohistochemistry, and molecular genetics matched those reported in the seven adult cases of sclerosing rhabdomyosarcoma. This is the first case report, to our knowledge, of this rare tumor arising in the pediatric age group, and we compare the features with those reported in adult sclerosing rhabdomyosarcoma.

Child, Preschool↗

Ophthalmic involvement as a presenting feature of nonorbital childhood parameningeal embryonal rhabdomyosarcoma.

OBJECTIVE: To describe presenting ophthalmic signs and symptoms in children with parameningeal rhabdomyosarcoma. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Twenty-three children with parameningeal rhabdomyosarcoma treated from 1978 through 1998. MAIN OUTCOME MEASURES: Each patient's presenting symptoms and history, the ophthalmic signs at presentation, the location of the tumor on computed tomographic scanning, the pathologic diagnosis after tumor biopsy, and the child's outcome after chemotherapy and radiotherapy. RESULTS: Eight of 23 patients with parameningeal rhabdomyosarcoma had ophthalmologic signs at presentation. All patients had sixth nerve palsies, and four had additional third nerve palsies. Fifth and seventh nerve involvement was seen in three children each, and two manifested additional fourth nerve palsies. In two patients, invasion of the optic canals and posterior orbit resulted in unilateral blindness in one and marked unilateral visual loss in the other. In no patient was the symptomatic history longer than 12 weeks. Seven of eight patients were treated with a combination of surgery, chemotherapy, and radiotherapy. The mean survival time for five patients who died from parameningeal rhabdomyosarcoma associated with ophthalmic signs was 27.2 months. Three patients are currently alive, with a mean survival time of 33.7 months after diagnosis. The survival time of 12 patients with parameningeal rhabdomyosarcoma and without ophthalmologic signs at presentation was better, in that nine are alive, with a mean survival time of 54 months. CONCLUSIONS: Advanced parameningeal rhabdomyosarcoma with skull base invasion may present with ophthalmic signs. These patients sought treatment late and had advanced tumors because their initial signs and symptoms were often attributed to more common ailments. Usually, the onset of the cranial nerve palsy initiated referral to the tertiary care center. The sixth nerve was the most vulnerable. Further invasion of the skull base or cavernous sinus may cause additional third, fourth, and fifth nerve palsies. The optic nerve was involved when the optic canals and orbit were encroached on by the tumor. The prognosis for survival was poor when these tumors were accompanied by ophthalmic signs.

Child↗

Clinical spectrum of primary ophthalmic rhabdomyosarcoma.

PURPOSE: To review the clinical presentation, histopathologic analysis, management, and ocular and systemic outcome of rhabdomyosarcoma affecting the ocular region. DESIGN: Retrospective, noncomparative, consecutive, interventional case series. PARTICIPANTS: Thirty-three consecutive patients with primary ophthalmic involvement of rhabdomyosarcoma from a single tertiary care center specializing in ocular oncology. MAIN OUTCOME MEASURES: Final visual acuity, treatment complications, local recurrence, and distant metastasis. RESULTS: The mean age at presentation was 10 years (median, 7 years; range, 1 month-68 years). At presentation, 8 patients (24%) were older than age 10 years and 4 patients (12%) were older than 20 years. The rhabdomyosarcoma was primarily located in the orbit in 25 cases (76%), conjunctiva in 4 cases (12%), eyelid in 1 case (3%), and uveal tract in 3 cases (9%). Symptoms or signs related to the tumor were present for a mean of 5 weeks and included proptosis in 10 patients (30%), eyelid swelling in 7 patients (21%), and blepharoptosis in 6 patients (18%). The initial diagnosis before referral to us included rhabdomyosarcoma in 8 cases (24%), conjunctivitis in 5 cases (15%), orbital or preseptal cellulitis in 5 cases (15%), idiopathic orbital inflammatory pseudotumor in 4 cases (12%), and others. Using the Intergroup Rhabdomyosarcoma Study Group staging and treatment protocols, the tumor was classified as group I in 4 cases (12%), group II in 12 cases (36%), group III in 16 cases (48%), and group IV in 1 case (3%). Treatment included surgical debulking and various regimens of chemotherapy and radiotherapy for the periocular tumors and enucleation for the three intraocular tumors. Local tumor recurrence was detected in 6 patients (18%). Orbital exenteration was necessary for tumor recurrence in 2 cases (6%). Long-term visual outcome of the 28 patients who maintained their globe was 20/20 to 20/40 in 11 patients (39%), 20/50 to 20/100 in 5 patients (18%), and 20/200 to no light perception in 12 patients (43%). Regional lymph node metastasis was detected in 2 patients (6%), one at initial visit and one after therapy. Distant metastasis occurred in 2 patients (6%), one detected at initial visit and one after therapy. With mean follow-up of 8.3 years, tumor-related death occurred in 1 patient (3%). CONCLUSIONS: Rhabdomyosarcoma can present in the orbit, eyelid, conjunctiva, and uveal tract. After treatment, local tumor recurrence occurs in 18%, metastasis in 6%, and death in 3%.

Adolescent↗

Identification of new genes related to the myogenic differentiation arrest of human rhabdomyosarcoma cells.

Rhabdomyosarcoma is a soft tissue tumor committed to the myogenic lineage but arrested prior to terminal differentiation. To identify new genes implicated in the block in myogenic differentiation of rhabdomyosarcoma cells and those responsible for their proceeding along the myogenic pathway we used cDNA microarrays to compare gene expression profiles of two clones of the human embryonal rhabdomyosarcoma cell line RD with different myogenic potentials: RD/12, which is unable to differentiate, and RD/18, which shows elements able to terminally differentiate, as defined by the expression of myosin heavy chain (up to 50% of the population) and the formation of multinucleated myotube-like structures. We identified 80 genes differentially expressed by the two clones. Differentiating RD/18 cells overexpressed the myogenic transcription factor myogenin along with known myogenic markers; myogenin transfection into undifferentiated RD/12 cells was able to revert the phenotype giving rise to 94% of clones displaying a differentiated morphology. RD/18 cells also expressed several genes not known to be expressed in rhabdomyosarcoma or muscle cells, such as pigment-epithelium derived factor and endothelin-3. Poorly differentiated RD/12 cells, along with genes related to mesenchymal lineage or early myogenic commitment, also expressed genes not previously known to be related to the differentiation block of human rhabdomyosarcoma, such as monocyte chemotactic protein-1, connective tissue growth factor and insulin-like growth factor binding protein-5. Differential expression of these genes in a time course of differentiation suggested their potential roles as either new myogenic markers or repressors of differentiation. These results identify a cluster of new genes related to the aberrant myogenic differentiation program of human rhabdomyosarcoma cells.

Cell Differentiation↗

Pleomorphic rhabdomyosarcoma of the larynx. A case report and review of the literature.

A case of pleomorphic rhabdomyosarcoma of the larynx occurring in a 33-year-old male is reported. The clinical and histopathological aspects of this undoubtedly rare neoplasm are described. After a quick review of the most important classifications of rhabdomyosarcoma so far made, the authors suggest a division into two basic groups, i.e. pleomorphic and fetal rhabdomyosarcoma, while the botryoid sarcoma and the alveolar rhabdomyosarcoma should be considered only as two subgroups of fetal rhabdomyosarcoma. From a comprehensive review of world literature on the subject, the well-documented cases up to now described are only seven, including the authors. The present case is the third one after the instances of pleomorphic rhabdomyosarcoma reported by Filipo and Crifo (1964 and by Rodriquez and Ziskind (1970).

Adult↗