1/10. rhabdomyoma of the orbit.To our knowledge, this is the first fully documented case of an adult-type orbital rhabdomyoma in an 8-year-old white boy, which originated in the belly of the medial rectus muscle and grew into the anterior orbit to incorporate the trochlea. Incomplete excision resulted in recurrence; the lesion was misinterpreted as a rhabdomyosarcoma and exenteration was performed. The patient was free of disease 25 years later. Reexamination of original pathologic material showed the typical histology of an adult-type rhabdomyoma. adult-type rhabdomyoma, the most differentiated tumor in a spectrum of benign and malignant striated muscle neoplasms, should be distinguished from fetal rhabdomyoma (also benign) and pleomorphic rhabdomyosarcoma, the malignant striated muscle tumor most likely to be confused with rhabdomyoma. An awareness of the benign nature of rhabdomyoma (rhabdomyoma never evolves into a sarcoma) should prevent unnecessary radical surgery. The tumor can be adequately managed by a local excision that includes all the lobulations of tumor within a margin of normal tissue.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
2/10. Mediastinal rhabdomyoma: a case report and review of the literature.An incidental anterior-superior mediastinal rhabdomyoma is reported in a 68-year-old man who died of hypovolemic shock as a result of massive blood loss due to transection of aorta after being hit by a moving motor vehicle. This is the third reported case of mediastinal rhabdomyoma in the literature. The immunohistochemical evidence of expression of muscle-specific markers supports the rhabdomyomatous nature of this neoplasm, and electron microscopic demonstration of haphazardly arranged myofilaments with prominent Z bands, "jack-straws" in the mitochondria, and the absence of desmosomes is supportive of extracardiac origin of this rhabdomyoma. The possible histogenesis of extracardiac adult rhabdomyoma (EAR) in the anterior-superior mediastinum from the thymic myoid cells is also discussed.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
3/10. Recurrent parapharyngeal rhabdomyoma. Evidence of neoplastic nature of the tumor from cytogenetic study.A 64-year-old Caucasian male with a left parapharyngeal mass had a past medical history that was significant for excision of a benign rhabdomyoma of the soft palate 30 years previously. Then 25 years ago, the tumor recurred in the palate and retropharyngeal space on the left and was reexcised. Histologic examination of all three excisions showed adult rhabdomyoma. Ultrastructural and histochemical studies of the second excision of this tumor have been published previously. The present study included histologic, ultrastructural, immunohistochemical, and cytogenetic analyses. The histologic and ultrastructural features of the tumor were identical to those reported 25 years ago. Immunohistochemical studies demonstrated that the tumor cells were desmin and myoglobin positive and vimentin negative. Focal positivity for CD56 was also present. Intracellular inclusions in the tumor cells were strongly positive for desmin. Cytogenetic examination of short-term cultures of the tumor cells demonstrated clonal chromosome abnormalities in 60% of metaphases. The majority of cells showed a reciprocal translocation between chromosomes 15 and 17 as the sole abnormality. A minor clone was characterized by abnormalities of the long arm of chromosome 10. The presence of clonal structural chromosome abnormalities in extracardiac adult rhabdomyoma lends strong support to the idea that these rare tumors are true neoplasms rather than hamartomatous or regenerative lesions.- - - - - - - - - - ranking = 4keywords = nature (Clic here for more details about this article) |
4/10. Crystal-storing histiocytosis associated with a lymphoplasmacytic neoplasm mimicking adult rhabdomyoma: a case report and review of the literature.Massive accumulation of crystals within histiocytes in association with a lymphoplasmacytic neoplasm causing histologic features closely mimicking adult rhabdomyoma is a rare occurrence. We report the case of a 49-year-old man who presented with a left posterior cervical mass. Histologic examination demonstrated sheets of large, elongated, and polygonal cells with prominent eosinophilic cytoplasm surrounding scattered dense lymphoplasmacytic collections. Evidence of the reactive histiocytic nature of the eosinophilic cells was provided by an immunohistochemical reaction that was positive with KP-1 (CD68), but negative with common muscle actin, desmin, and myoglobin. The ultrastructural finding of elongated and rhomboid, membrane-bound, cytoplasmic crystals further supported the reactive histiocytic nature of these cells. B-cell kappa monoclonality of the lymphoplasmacytic component was proven by gene rearrangement studies. A recurrence involving the right parotid gland, 18 months after removal of the cervical mass, confirmed the aggressive nature of this B-cell lymphoma. Misdiagnosis of crystal-storing histiocytosis as adult rhabdomyoma can be avoided if the following features are recognized: lack of cytoplasmic cross striations, frequent multinucleation of the histiocytes, and prominence of the atypical lymphoplasmacytic component.- - - - - - - - - - ranking = 3keywords = nature (Clic here for more details about this article) |
5/10. Malignant mixed mullerian tumor of the ovary. Report of a case studied by immunohistochemistry.A case of malignant mixed mullerian tumor of the ovary in a 57-year-old woman is reported along with the results of an immunohistochemical study. The tumor, measuring 16 x 10 x 9 cm, was composed predominantly of adenocarcinoma with a smaller amount of anaplastic carcinoma as an epithelial component and chondrosarcoma, liposarcoma, fibrosarcoma and rhabdomyoblasts as mesenchymal elements. immunohistochemistry using paraffin sections demonstrated cytokeratin (CK) and epithelial membrane antigen (EMA), generally regarded as epithelial markers, not only in the epithelial component but also in chondrosarcoma cells. vimentin and desmin, generally regarded as mesenchymal markers, were exhibited partly in carcinoma cells as well as in mesenchymal elements. Positive staining for S-100 protein was obtained not only in chondrosarcoma and liposarcoma cells, but also partly in adenocarcinoma cells. This intricate immunohistochemical picture reflected the histologic findings. It is noteworthy that both carcinoma cells and chondrosarcoma cells demonstrated simultaneous expression of CK, EMA, vimentin, desmin and S-100 protein. This somewhat unusual antigen expression by tumor cells may indicate a change in the nature of tumor cells due to microenvironmental factors.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
6/10. Rhabdomyomatosis of newborn lung: a case report with immunohistochemical and electronmicroscopic characterization of striated muscle cells in the lung.Interstitial proliferation of striated muscle cells in the lung is rare. A few cases in the literature only document infants with associated lung and other major organ anomalies incompatible with long-term survival. In this report we document a case of diffuse patchy interstitial proliferation of striated muscle cells in the left lung and confirm their nature by immunohistochemistry and electron microscopy. In particular, we show that these skeletal muscle cells express alpha-sarcomeric actin, but not alpha-smooth muscle actin, indicating an antigenetically well-developed striated muscle phenotype despite morphologically embryonal features.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
7/10. Intracranial trigeminal nerve rhabdomyoma/choristoma in a child: a case report and discussion of possible histogenesis.Rhabdomyomas are rare tumors that usually arise within the heart, orocervical, or vulvovaginal regions. The cardiac tumors have a characteristic immature morphology, occur often in association with tuberous sclerosis, and are regarded as hamartomas rather than true neoplasms. The histogenesis of the extracardiac tumors and their true neoplastic nature are matters of controversy. We report the first case of a rhabdomyoma located inside the cranium. The intimate association with the mandibular division of the trigeminal nerve, the normal embryogenesis of the craniofacial muscles, and animal homograft and xenograft experiments provide a framework for considering this tumor, and possibly other rhabdomyomas, as a choristoma/hamartoma rather than a true neoplasm.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
8/10. Extracardiac rhabdomyoma: a report of two cases.Two case reports of extracardiac rhabdomyoma (adult type) are presented. The rare occurrence of extracardiac rhabdomyoma and its relatively benign nature makes a histological diagnosis very necessary, though often difficult to make. In both cases reported here, a diagnosis of extracardiac rhabdomyoma was given and treatment with local excision yielded good results. The importance of a histological diagnosis and treatment by only a local excision is stressed.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
9/10. rhabdomyoma of the larynx: a rare cause of stridor.Rhabdomyomas of the larynx are rare tumours. In the literature to date 18 cases have been reported. They usually present with slowly progressive symptoms typical of their benign nature. We present a case that has many atypical features for an 'adult' type rhabdomyoma and discuss the relevant associated literature.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
10/10. neurocytoma/rhabdomyoma (myoneurocytoma) of the cerebellum.An unusual case of cerebellar neurocytoma with rhabdomyomatous differentiation in a 6-year-old boy is reported. Immunocytochemical and ultrastructural features of the tumour were studied. Abortive synapse formation, the presence of clear vesicles and synaptophysin immunoreactivity of the tumour cells indicated its intermediate neuronal differentiation, while the presence of myoblasts and myotubes and immunolabelling by desmin confirmed the rhabdomyomatous differentiation. In addition, the mesenchymal cells variably expressed neurofilament protein and glial fibrillary acidic protein, suggesting inductive interaction between the neuroectodermal and ectomesenchymal elements and persistence of the pleuripotential nature of the cells along the rhombic area of the brain stem.- - - - - - - - - - ranking = 1keywords = nature (Clic here for more details about this article) |
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