Pediatric Sclerosing Rhabdomyosarcoma
Sclerosing rhabdomyosarcoma, a particular phenotypic variant of rhabdomyosarcoma initially described in the adult population, has emerged as a potential pitfall in the evaluation of pediatric sarcomas. Because of its densely hyalinized collagenous matrix and its occasional expression of a pseudovascular pattern of growth, sclerosing rhabdomyosarcoma has been at times misdiagnosed as chondrosarcoma, osteosarcoma, or angiosarcoma. We describe 3 pediatric patients with sclerosing rhabdomyosarcoma and provide a detailed description of its distinguishing pathologic features. Awareness about this rhabdomyosarcoma variant and careful immunophenotypical evaluation are necessary to establish the correct diagnosis. Although no specific genetic aberrations have been recognized, yet the cytogenetic findings in 2 tumors of this series suggest a link with embryonal rhabdomyosarcoma. It is likely that further genotyping will result in better nosologic delineation of sclerosing rhabdomyosarcoma and that it will uncover pathogenetically and prognostically relevant genes.
Available from: Amandeep Kumar
- "SRMS shares clinicopathological features both with ERMS and ARMS. The presence of strap cells [5, 8, 11], involvement of urinary bladder , the presence of areas with spindle cells [7, 11], more prominent expression of MyoD1 over myogenin [5, 7–9, 11], and gain of chromosomes on karyotyping in some cases point towards ERMS [7, 11, 12]. However, common extremity involvement is unusual for ERMSs [5, 8]. "
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ABSTRACT: Sclerosing RMS (SRMS) is a recently described subtype of RMS that has not yet been included in any of the classification systems for RMSs. We did pubmed search using keywords "sclerosing, and rhabdomyosarcomas" and included all pediatric cases (age ≤ 18 years) of SRMSs in this review. We also included our case of an eleven-year-old male child with skull base SRMS and discuss the clinical, histopathological, immunohistochemical, and genetic characteristics of these patients. Till now, only 20 pediatric cases of SRMSs have been described in the literature. Pediatric SRMS more commonly affects males at a mean age of 9 years. Extremeties and head/neck regions were most commonly affected. Follow-up details were available for 16 patients with mean follow-up of 25.3 months. Treatment failure rate was 43.75%. Overall amongst these 16 patients, 10 were alive without disease, 4 were alive with disease, and two died. Thus, overall and disease-free survival amongst these 16 patients were 87.5% and 62.5%, respectively. The literature regarding clinical behaviour and outcome of pediatric patients with SRMSs is patchy. Detailed molecular/genetic analysis and clinicopathological characterization with longer follow-ups of more cases may throw some light on this possibly new subtype of RMS.
Available from: Jody E Hooper
- "With fewer than 30 cases reported, genetic analysis has been limited. To date, only six karyotypes    and one comparative genomic hybridization  have been reported showing aneuploidy with numerous chromosomal gains but noregional amplifications   . Reciprocal translocations typical of alveolar rhabdomyosarcoma, either t(1;13)(p36;q14) or t(2;13)(q35;q14), have not been present. "
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ABSTRACT: A rare sclerosing variant of rhabdomyosarcoma characterized by prominent hyalinization and pseudovascular pattern has recently been described as a subtype biologically distinct from embryonal, alveolar, and pleomorphic forms. We present cytogenetic and molecular findings as well as experimental studies of an unusual case of sclerosing rhabdomyosarcoma. The primary lesion arose within the plantar subcutaneous tissue of the left foot of an otherwise healthy 23-year-old male who eventually developed pulmonary nodules despite systemic chemotherapy. Two genetic abnormalities identified in surgical and/or autopsy samples of the tumor were introduced into 10T1/2 murine fibroblasts to determine whether these genetic changes cooperatively facilitated transformation and growth. Cytogenetic analysis revealed a complex abnormal hyperdiploid clone, and MDM2 gene amplification was confirmed by fluorescence in situ hybridization. Cancer gene mutation screening using a combination of multiplexed PCR and mass spectroscopy revealed a PIK3CA exon 20 H1047R mutation in the primary tumor, lung metastasis, and liver metastasis. However, this mutation was not cooperative with MDM2 overexpression in experimental assays for transformation or growth. Nevertheless, MDM2 and PIK3CA are genes worthy of further investigation in patients with sclerosing rhabdomyosarcoma and might be considered in the enrollment of these patients into clinical trials of targeted therapeutics.
Available from: Cristian Ortiz Villalon
- "The histogenic relationship between sclerosing rhabdomyosarcoma and the other types of rhabdomyosarcomas remains unclear although cytogenetic studies have suggested a link with embryonal rhabdomyosarcoma [11,13,14]. "
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ABSTRACT: Sclerosing rhabdomyosarcoma (SRMS) is an infrequent variant of rhabdomyosarcoma characterized by extensive intercellular hyaline fibrosis. We report the case of a 37 year-old male with a 9 x 6 cm SRMS on the right elbow. Histologically, the tumor showed an abundant extracellular hyaline matrix with extratumoral vascular emboli and microscopic foci of fusocellular embryonal rhabdomyosarcoma (FRMS) separated by a fibrotic band from the sclerosing areas. One year later the patient presented with a right intratesticular tumor of 1.2 x 0.8 cm, which was reported as pure FRMS. Immunohistochemically, SRMS was positive only for MyoD1 and Vimentin and negative for Myogenin and Desmin. Both the elbow emboli with the extratumoral foci of FRMS and the intratesticular tumor were positive for Myogenin, MyoD1, Vimentin and Desmin. Using fluorescent in situ hybridization (FISH), the SRMS and the FRMS tumor cells of the elbow and the FRMS tumor cells of the testis were found to be negative for FOXO1A translocation in chromosome 13. PCR chimeric transcriptional products PAX3-FKHR and PAX7-FKHR were not found. Six months following testicular resection, the patient died of multiple metastases in the mediastinum, lung and right thigh.
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