The monster villus: A rare, but characteristic, feature of human placentas in diabetes mellitus

Presence of paw-shaped stem villi branching into multiple functional villi, i.e. monster villi, may indicate the missing switch from branching to non-branching angiogenesis during villous development at 26-28 weeks of gestation. This specific morphological and vascular arrangement of the villous tree only occurred in cases with T1D and additional pathologies, conditions with elevated fetal insulin.