Spindle cell rhabdomyosarcoma (so-called) in adults: report of two cases with emphasis on differential diagnosis.

Spindle cell rhabdomyosarcoma (RMS) is a recently described variant of embryonal RMS that carries a relatively favorable prognosis when compared with other forms of RMS. To date, spindle cell RMS has been described only in children. The authors have identified two unusual cases occurring in adults using the following criteria: tumors composed mainly of fascicular, relatively monomorphic spindle-shaped cells that show unequivocal immunohistochemical and ultrastructural evidence of myogenic differentiation. The tumors were identified in a 38-year-old woman and a 56-year-old man, arising in the cheek and left hemidiaphragm, respectively. Both were treated with surgical resection and chemotherapy. The first patient died of uncontrolled local recurrence of her tumor at 27 months after diagnosis, and the second died of metastatic disease at 13 months follow-up. The tumors were composed mainly of fascicles of spindle cells with palely eosinophilic cytoplasm admixed diffusely with sparse polygonal, rounded, or strap-shaped rhabdomyoblasts with brightly eosinophilic cytoplasm and with cross-striations in the first case only. Immunostaining for muscle-related antigens showed staining for smooth-muscle actin (focal), pan-actin HHF-35, desmin, fast myosin, myoglobin, and MyoD1. Both cases were negative for S-100 protein. On electron microscopy, both cases showed neoplastic rhabdomyoblasts with clear-cut sarcomeric differentiation in many of the tumor cells. Spindle cell RMS poses special problems in differential diagnosis when arising in adults and should be distinguished from leiomyosarcoma, malignant peripheral nerve sheath tumor with heterologous rhabdomyoblastic differentiation (malignant Triton tumor), and fibrosarcoma. In view of the good prognosis afforded children with spindle cell RMS and in light of the chemoresponsive behavior of RMS in general, we feel that it is important to identify tumors that meet the criteria for spindle cell RMS occurring in the adult population. However, based on these two cases, it is possible that spindle cell RMS occurring in adults may not be associated with such a favorable outcome.

Sarcoma botryoides of the extrahepatic bile ducts. A light- and electron microscopic study of a case.

The clinical, light- and electron microscopic features of a sarcoma botryoides of the common bile duct of a 2 1/2-year-old boy are reported. Despite the absence of cross-striation under the light microscope, many tumour cells were found to contain abundant thin and thick filaments arranged in a sarcomere-like pattern at the electron-microscopic examination of originally paraffin-embedded material. Ultrastructural examination of embryonal rhabdomyosarcoma may be of value for a definite diagnosis also when only formalin-fixed and paraffin-embedded material is available.

Rhabdomyosarcoma of the oral cavity. Report of four cases.

Clinical and pathologic findings of four cases of rhabdomyosarcoma of the oral soft tissues are described that include findings from immunohistochemistry and electron microscopy. Three cases occurred in children under 16 years of age and one in a 22-year-old. Included is a brief discussion on reported gene abnormalities that may contribute to neoplastic development.

Sarcoma botryoides of the cervix. Report of a case with cytopathologic findings.

BACKGROUND: Cytologic findings of sarcoma botryoides were still equivocal because sarcoma botryoides of the uterine cervix is an extremely rare neoplasm, and few cases have been reported to date. CASE: A 17-year-old female was diagnosed with sarcoma botryoides of the uterine cervix. The entire vaginal canal was occupied with polypoid masses, which arose from the anterior lip of the uterine cervix, and the tumor was classified as group I (Intergroup Rhabdomyosarcoma Study). After wedge resection and six courses of combination chemotherapy, the tumor recurred in the same location of the cervix as the primary lesion. Touch smear of the polypoid mass formed loose clusters and also showed short spindle cells in a necrotic background. The nucleus of the tumor cells had a thin nuclear membrane, fine chromatin pattern and partly clear nucleolus, showing mild nuclear atypia. Immunohistochemically, some of the tumor cells showed positive staining for myoglobin and desmin. CONCLUSION: The cytologic findings of sarcoma botryoides of the female genital tract are typical features of nonepithelial malignant tumor. Immunohistochemical study is useful for the diagnosis of rhabdomyosarcoma.

Embryonal rhabdomyosarcoma arising in the buccal mucosa: a case report with immunohistochemical and electronmicroscopic findings.

Rhabdomyosarcoma is one of the most common soft-tissue neoplasms in children. We report a case of a 9-year-old female with embryonal rhabdomyosarcoma arising in the buccal region with immunohistochemical and electronmicroscopic findings. Under a light microscope, it was observed that the tumor was composed of small round or spindle-shaped cells with pleomorphic and hyperchromatic nuclei. They were immunoreactive for actin, myoglobin and desmin. With an electron microscope, it was found that most tumor cells contained filamentous structures and free ribosomes. Some of them showed typical myofilaments, M-bands and Z-lines. These findings were specific evidence of rhabdomyosarcoma. Twenty courses of VAC (vincristine, D-actinomycin and cyclophosphamide) chemotherapy were administered, followed by surgical resection of the tumor.

Urinary bladder rhabdomyosarcoma (sarcoma botryoides) in a young Newfoundland dog.

A 13-month-old female Newfoundland dog suffered from urinary bladder tumor. Histologically the tumor consisted of round or fusiform cells, occasionally having eosinophilic cytoplasms. Apparent mature rhabdomyoblasts possessing elongated eosinophilic cytoplasm and cross striations were infrequently observed. The tumor cells exhibited immuno-positive for anti-myoglobin, desmin and vimentin antibodies. Ultrastructurally, tumor cells have abundant myofibrils in their cytoplasm and Z bands were also detected. The present tumor was diagnosed as a urinary bladder rhabdomyosarcoma in a Newfoundland dog, which has not been frequently reported in dogs.

[Unusual site of an embryonal rhabdomyosarcoma of the mesenchymal hepatic pedicle]. / Localisation inhabituelle d'un rhabdomyosarcome embryonnaire du mésenchyme pédiculaire hépatique.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of children. Tumors arising in the extrahepatic biliary tree are extremely rare (less than 1% of cases). In this location, most are RMS of the botryoid type. We report a case of a 10-year-old child with embryonal RMS arising in the mesenchyma of the hepatic pedicle. Most tumor cells were large, round with abundant eosinophilic cytoplasm. A few cells were small round or spindle-shaped. Tumor cells showed positive immunostaining for muscle markers: desmin and sarcomeric actin. Electron microscopy revealed 2 types of cells: some were undifferentiated and others showed striated muscle differentiation features.

Subcutaneous embryonal rhabdomyosarcoma in a dog: cytologic, immunocytochemical, histologic, and ultrastructural features.

A subcutaneous mass on the left antebrachium of an 11-year-old intact female English Pointer dog was evaluated presurgically by cytologic examination and immunocytochemical staining. The sample consisted of discrete, variably sized, markedly pleomorphic neoplastic cells that expressed vimentin with diffuse cytoplasmic staining, desmin with focal paranuclear staining, and myoglobin with diffuse cytoplasmic staining, consistent with a diagnosis of rhabdomyosarcoma. Lymphocytic and histiocytic markers were negative. Aspirates of the enlarged ipsilateral prescapular lymph node were positive for metastatic disease. Surgical excision of the tumor and lymph node were followed by histologic and electron microscopic examination. Histomorphologic appearance of neoplastic cells from the mass and the lymph node paralleled cytologic findings; the histologic diagnosis was round cell variant of embryonal rhabdomyosarcoma. By ultrastructural evaluation, cells contained numerous mitochondria and masses of cytoplasmic tangled myofilaments, features typical of rhabdomyoblasts. The dog received doxorubicin (30 mg/m(2) ) every 3 weeks for 5 treatments. Local recurrence developed 6 months after resection but was not treated. Despite a guarded prognosis and untreated local recurrence, the dog was still alive 18 months after surgery. Cytologic evaluation and immunocytochemical staining were pivotal for the presurgical diagnosis of rhabdomyosarcoma.

Ultrastructural characterization of poorly differentiated rhabdomyosarcomas.

Twenty-five rhabdomyosarcomas, histopathologically and immunocytochemically classified as embryonal (12 cases), alveolar (11 cases), and pleomorphic (two cases), were studied by routine and immunogold electron microscopy, to identify, in poorly differentiated cells, reproducible markers useful for diagnostic purposes. Rhabdomyoblasts with rudimentary sarcomeres were observed in 12 cases (48%). Large cells (named oval cells) with an oval shape and an eccentric nucleus, like rhabdomyoblasts but lacking organized myofilaments, were observed in 20 cases (80%). By immunogold electron microscopy, performed on four of 25 cases, both oval cells and rhabdomyoblasts showed abundant intermediate filaments positive for desmin. Oval cells may be used as markers of poorly differentiated rhabdomyosarcomas.

Low sample volume causes differentiation in human rhabdomyosarcoma cell line RD subjected to electroporation.

Gene transfection has been accomplished with a variety of techniques such as DEAE dextran, calcium phosphate coprecipitation, protoplast fusion, liposomes, microinjection and recombinant bacteriophages. However, transfection by electroporation, consisting of the reversible permeabilization of cell membranes after exposure to a pulsed electric field, has been shown to be the most rapid, simple and efficient method for the stable incorporation of genes in different cell lines. We studied rhabdomyosarcoma cells subjected to electroporation in two different vol. [400 microliters (group 1) and 150 microliters (group 2] of 140 mM NaCl/15 mM Hepes buffer, pH 7.2) and evaluated the effects of electroporation volume on growth and differentiation. Low sample volumes induced a terminal process of morphological and ultrastructural myogenic differentiation in rhabdomyosarcoma cells, which concluded with cell death. Our results suggest that in electroporation low sample vol. of rhabdomyosarcoma cells induced morphological and phenotypic differentiation, with increased expression of desmin, alpha-actinin and tropomyosin.

Differentiation of a human rhabdomyosarcoma cell line after antineoplastic drug treatment.

The feasibility of treating solid tumours with differentiation therapy using antineoplastic drugs is currently being investigated, but the emergence of multidrug resistance remains the major limitation to this therapeutic approach. A rhabdomyosarcoma cell line resistant to actinomycin D (RD-DAC) has been used as an in vitro model to investigate, with light and electron microscopy, the degree of differentiation in multidrug-resistant cells. The parental cell line (RD), derived from a human embryonic-type rhabdomyosarcoma, is undifferentiated, with no evidence of specific ultrastructural markers. Examination of resistant cells by transmission electron microscopy revealed myofilaments arranged parallel to the long axis of the cell, which was considered clear evidence of myogenic differentiation. These observations suggest that actinomycin D, the drug of choice in the treatment of rhabdomyosarcoma, induces differentiation in the cell line RD. It is postulated that multidrug resistance can interfere with cellular differentiation.

Rhabdomyosarcoma. Morphologic, immunohistochemical, and DNA study.

In this study 80 cases of predominantly adult rhabdomyosarcoma are presented as follows: 20 cases of the embryonal type, 32 cases of the alveolar and 8 cases of the pleomorphic type. Additional histologic classification was performed in each type. In myotube stage the histologic picture of fetal muscles cannot be compared to the alveolar type of rhabdomyosarcoma. Desmin and sarcomeric actin are observed in 47.7% of all cases, and myoglobin and myosin in only 23.1%. The reactions were diffuse, disperse, or focal. Electron microscopic study subdivides desmin positive tumors into three groups of differentiation. DNA analysis shows that most desmin positive cells are diploid in comparison to all the tumor cells that are hyperdiploid and tetraploid.