Rabdomiosarcoma embrionario en un perro

Resum

Rhabdomyosarcomas are malignant tumours that are common in humans, but uncommon in veterinary pathology. The case presented resembles histologically human embryonic type: poorly demarcated mass, unencapsulated and with two cell populations: immature skeletal muscle fibers at different stages of differentiation and undifferentiated small fusiform mesenchymal cells in the central portions of the tumor. The most accurate technique in order to confirm the diagnosis is immunohistochemistry. The neoplastic cells are negative or weakly positive to vimentin, negative to cytokeratin and positive to desmin and myoglobin. In the sample of this study, immature skeletal muscle fibers match this description but undifferentiated mesenchymal cells were strongly positive to vimentin and negative to myoglobin, desmin and cytokeratin. According to histological and immunohistochemical findings, we conclude that is more precise to consider rhabdomyosarcomas in dogs as tumours arising from primitive mesenchymal cells with the ability to differentiate into striated muscle that as neoplasms derived from differentiated striated muscle cells.