Fig. 2.

Pathology slides for Case #2. A. Sarcoma botryoides (4x): The cambium layer (green arrows) is represented by a subepithelial layer of the spindle cell neoplasm. B. Sarcoma botryoides (14x): Higher power review of the cambium layer. On high-power, the spindled cells can sometimes demonstrate the cross striations of skeletal muscle (INSET: rhabodomyoblasts). C. Alveolar rhabdomyosarcoma (6x): A significant component of this patient’s very large tumor demonstrated a nested pattern of the small round blue cell tumor, also referred to as “alveolar” differentiation of a rhabdomyosarcoma, or alveolar rhabdomyosarcoma. D. Sarcoma botryoides (17x): This portion of the tumor demonstrates a vascular extension (LVI) of the small round blue cell (alveolar) component of the tumor in a background of spindle cell differentiation. E. Myogenin (20x): Microphotography showing nuclear positivity for myogenin. F. Myogenin (40x): Higher power view of microphotography showing nuclear positivity for myogenin. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)