Spot diagnosis: a child plus painless rectal bleeding plus a smooth, glistening, cherry-red ball on a stalk equals a juvenile polyp. The look alone, the so-called cherry tumour, is enough to name it.
Run the options out: Peutz-Jeghers is the one you tie to dark spots on the lips and buccal mucosa with multiple small-bowel hamartomas, not a solitary shiny rectal ball. A villous adenoma is the opposite picture, a broad, sessile, cauliflower-like growth in an older adult that can mimic a secretory diarrhoea and carries real malignant risk. Hyperplastic polyps are the trivial, tiny, pale bumps you ignore.
The clinical course of a juvenile polyp fits a young child: it bleeds, and if the stalk is long it can prolapse out of the anus during straining and hurt. It is a hamartoma and is benign. So the bright red pedunculated sphere in a child is the juvenile polyp. Ref: Bailey & Love, 27th ed.