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Primary tumors of the external and middle ear. III. A clinicopathologic study of embryonal rhabdomyosarcoma.

Embryonal rhabdomyosarcoma of the middle ear-mastoid is a highly lethal neoplasm of childhood in most cases, which clinically simulates a chronic infection. Extensive hemorrhage and necrosis in the biopsy specimen may obscure and often delay the diagnosis. Two of the six embryonal rhabdomyosarcomas in this study showed histologic evidence of differentiation. These same two patients were the only long-term survivors. Similar examples of "differentiated" embryonal rhabdomyosarcomas of the middle ear-mastoid with prolonged survival have been recorded individually in the literature. Therapeutic implications of this finding have been discussed.

Child

Diagnostic value of histochemistry in embryonal rhabdomyosarcoma.

Embryonal rhabdomyosarcomas from the nasopharynx of two children were examined by histochemical methods commonly applied to muscle biopsies. These stains included nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR), succinate dehydrogenase (SDH), PAS, PAS-diastase, myophosphorylase, calcium-mediated adenosine triphosphatase (ATPase) preincubated at high and low pH, and oil red O. Myofibrils were easily identified with ATPase and blood vessel walls were also stained. NADH-TR clearly showed longitudinal and cross-striations that were not seen with H&E or PTAH stains. The modified Gomori trichrome stain additionally contributed to the recognition of myofibrils. Some techniques of muscle histochemistry applied to fresh frozen sections of tumor tissue may provide evidence of muscular differentiation in otherwise poorly differentiated sarcomas for a more accurate diagnosis of rhabdomyosarcoma.

Child, Preschool

[Ultrastructure and formal pathogenesis of embryonal rhabdomyosarcoma (author's transl)].

An embryonal rhabdomyosarcoma of the nasopharynx of a 10 year old boy is analysed with light and electron microscopy. With regard to cell shape and cytoplasmic features the following four tumour cell types could be distinguished: 1. Undifferentiated mesenchymal cells with a big loosely packed nucleus and a small cytoplasmic rim with only few cell organelles; 2. Undifferentiated tumour cells with a broad cytoplasmic body which contains a dense network of nonspecific intermediate filaments with a diameter of about 100 A; 3. Immature rhabdomyoblasts with randomly orientated specific myofilaments; 4. Fully differentiated rhabdomyoblasts with well developed myofibrils often showing a sarcomeric pattern. Glycogen deposits which were seen in great masses in many tumour cells were regarded to result from degenerative processes within the tumor. The cellular stages in the development of rhabdomyoblasts are basically identical to those known from the embryogenesis and regeneration of striated muscle. From these observations the two following developmental pathways are suggested: 1. Origin of the tumour from an undifferentiated mesenchymal cell; 2. Atypical regeneration of striated muscle which terminates in malignant progressive tumour growth. At present, the body of information about rhabdomyosarcomas supports the assumption of an origin from immature mesenchymal cells. Nevertheless, the second theory cannot be totally excluded.

Cell Differentiation

The diagnostic usefulness of electron microscopy investigation of orbital embryonal rhabdomyosarcomas.

The ultrastructural study of three malignant orbital tumors, only one of which was correctly diagnosed as embryonal rhabdomyosarcoma upon histologic examination, is reported. In all 3 cases electron microscopic investigation revealed the presence of rhabdomyoblasts. These are easily recognizable in one case in which the diagnosis was made on the basis of the optical microscopic study. The other two cases needed further tests to evince rhabdomyoblasts. The importance of an ultrastructural study for a histogenetic characterization of this kind of tumor is emphasized. As far as embryonal rhabdomyosarcomas are concerned the electron microscopic study is possible, and it gives useful results even when material fixed with routine histologic methods (formalin, Bouin's solution) are used.

Child

[Embryonal rhabdomyosarcoma of the orbit. Apropos of 24 cases].

A composite review of 24 cases of embryonal rhabdomyosarcoma which is seen in fact to be the commonest orbital malignant tumour in children. In its evolution, most often very rapid, sometimes pseudo-inflammatory, this tumour presents many different histological appearances among which the alveolar form and the botryoidal form should be particularly distinguished. Although it was for a long time confused with reticulosarcoma the tumour is in fact derived from primitive undifferentiated mesenchymal cells and can therefore in this sense be considered as a blastoma. Since the prognosis is grave and its treatment often disappointing, it should in many cases combine surgery with radiotherapy and polychemotherapy.

Adolescent

Embryonal rhabdomyosarcoma of the ampulla of vater.

The first case to appear in the world literature is described of an embryonal rhabdomyosarcoma in a child arising from the region of the ampulla of Vater and projecting into the lumen of the duodenum.

Ampulla of Vater

Orbital embryonal rhabdomyosarcoma and intracranial schwannoma.

A 39-year-old woman had a large benign intracranial schwannoma of the Gasserian ganglion. Thirty-two years previously, she had an embryonal rhabdomyosarcoma of the orbit. She had been treated by enucleation, local excision, and low-dose supplemental irradiation (1,400 rads). This is the longest survival of which we are aware following any treatment modality in such tumors. No correlation between the two tumors has been established.

Adult

Embryonal rhabdomyosarcoma of the middle ear.

An embryonic sarcoma of the middle ear occurring in a child has been described. The mainstay of treatment has been triple therapy. The child is well 4 years and 3 months after diagnosis.

Child, Preschool

Electron microscopic and electron histochemical studies on embryonal rhabdomyosarcoma of the orbit.

A small number of differentiated tumor cells could be found besides a great number of undifferentiated ones. Abnormal dense granules were found in the nuclei of undifferentiated tumor cells, not in differentiated ones. Non-specific filaments were seen in the cytoplasm of undifferentiated tumor cells. Differentiated tumor cells demonstrated various stages of myofibrillar structures such as A, I, and Z bands, many glycogen granules, mitochondria and a basement membrane. Polyglucose particles synthesized from glycose-1-phosphate by phosphorylase activity were located in the cytoplasmic matrix of undifferentiated and differentiated tumor cells and in the karyolymph of undifferentiated tumor cells. Polyglucose partices increased in number according to the degree of differentiation of tumor cells.

Basement Membrane

DNA Methylation Profiling of Pediatric Ectomesenchymoma Supports Embryonal Rhabdomyosarcoma-Like Epigenetic Identity.

Ectomesenchymoma is a rare, biphenotypic pediatric tumor combining rhabdomyoblastic and neuroectodermal differentiation. We characterize two novel cases through integrated genomics and the first report of genome-wide DNA methylation profiling. Both tumors harbored RAS-pathway mutations (HRAS p.Gly13Arg; NRAS p.Gln61His). Methylation analysis, including microdissected components, consistently aligned ectomesenchymoma with the embryonal rhabdomyosarcoma superfamily, revealing a shared myogenic epigenetic program despite neural differentiation. Shared copy-number profiles across distinct histological regions supported a monoclonal origin. Overall, our data support a close biological relationship between ectomesenchymoma and embryonal rhabdomyosarcoma and indicate that RAS-pathway testing and methylation profiling can significantly refine diagnostic precision.

Humans

Changing concepts in management of pelvic rhabdomyosarcoma in children.

Survival with embryonal rhabdomyosarcoma of all sites has improved dramatically in recent years with the increased use of long-term, cyclic, multidrug chemotherapy. Protocols have been established and are currently being evaluated by the Intergroup Rhabdomyosarcoma Study. The management of embryonal rhabdomyosarcoma of the pelvic viscera, though, remains troublesome. Limited surgical excision is rarely possible and high-dose radiotherapy to the bony pelvis may cause severe and disabling growth disorders. Yet, survival with these lesions is increasing as with rhabdomyosarcoma from all sites and is directly related to a well-planned and aggressive multidisciplinary program. We have seen 12 cases of pelvic rhabdomyosarcoma within the last seventeen years at this institution. These cases will be reviewed in regard to varying modes of therapy and survival. Our current therapeutic approach, based on national and local experience, will be presented.

Child