Rhabdomyosarcoma Sarcoma Botryoides

A 4-year-old boy presents with 3 months of progressive nasal obstruction, blood-stained nasal discharge, and recent left-sided proptosis. Anterior rhinoscopy reveals the structure marked **B** — multiple friable polypoid grape-like translucent grayish-pink masses filling the nasal cavity and herniating into the posterior choana. Endoscopic biopsy shows a hypocellular myxoid stroma with a dense subepithelial cambium layer of small round-to-spindle rhabdomyoblasts. Immunohistochemistry is positive for desmin, myogenin, and MyoD1. Which gross pathologic appearance is classic for this tumor and explains the origin of its histologic subtype name?