Most common childhood polyp, usually
children < 5 years, 80% in rectum.
Commonly presents with rectal
Usually sporadic; rarely associated
with juvenile polyposis syndrome.
Not neoplastic by themselves, but may
be associated with dysplasia.
Gross: hamartomatous, large lesions
with long (1-2 cm) stalks, red granular or glistening surface; may
see cystic cavities.
Micro: granulation tissue and ulcer
on the surface, cystically dilated glands filled with mucus,
edematous and inflamed stroma; often hyperplastic changes; minimal
epithelium or smooth muscle; no atypia; occasionally foreign-body
giant cell reaction to ruptured glands.
Familial juvenile polyposis:
autosomal dominant, SMAD4 gene mutation, no PTEN or BMPR1