[Labial embryonal rhabdomyosarcoma. Value of cell culture and electron microscopy, histogenesis].

The authors report the case of a labial embryonal rhabdomyosarcoma of a baby. This appears to be an exceptional localization. The study of the first biopsy which was too superficial leads to the thought of a capillary angioma. At the age of 6 months the lesion is 35 mm in diameter, a lobulated formation, typically botryoid. The excision after a frozen section control was in healthy tissue. At the age of 10 months, there is a local relapse with a nodule of 18 mm with left submandibular lymph nodes. A second surgical operation allows the culture of the tumoral tissue. The conventional histopathological examinations shows the aspect of an embryonal rhabdomyosarcoma. On the ultrastructural examination one can visualize in some cells an intracytoplasmic filamentous material. The cellular proliferation in culture, after May Grunwald Giemsa coloration is monomorphous, spindle shaped and of fibroblastic aspect. The ultrastructural study of this cellular proliferation after trypsinization on the 7th day shows some cells including an intracytoplasmic filamentous material. On the data of the cellular culture, the ultrastructural studies and the review of the literature, the authors discuss the possibility of the relationship between the cells of embryonal rhabdomyosarcomas and the fibroblasts and myofibroblasts. Embryonal sarcoma seems to be a better denomination than embryonal rhabdomyosarcoma, as regards the histogenesis.