The Constriction Ring of Amniotic Band Syndrome Reveals Idiosyncrasies of Wound Repair in Infancy

ABSTRACT We hypothesized that the constriction rings in Amniotic Band Syndrome (ABS) are the sequelae of localized mechanical injury. Typical scarring pattern was examined in skin tissue of ABS origin, containing an amniotic band constriction, for collagen and elastin distribution, and the ratio of collagen I to collagen III (CI:CIII). A skin sample from an extra finger was the control. In the ABS specimens, sub-epidermal structures were intact and present throughout, and collagen I exhibited a normal basket-weave pattern. At the site of constriction in both ABS samples, reticular dermis elastin fibers were fragmented and papillary dermis elastin fibers were absent. In the control tissue, the reticular dermis contained relatively thick, branching fibers of elastin, and papillary dermis elastin was present. The elastin fragmentation at the constriction ring indicates localized elastin remodeling in response to injury. The absence of elastin in the papillary dermis of the constriction likely indicates a localized disruption in elastin formation. The formation and deposition of collagen and the presence of sub-epidermal structures favor a non-scarring phenotype, while the organization of elastin favors that of localized scarring. Summary Statement A rare, fetal model of healing after constrictive injury of skin, in which elastin fragmentation at the constriction injury indicates remodeling explained by the differential expression of elastin during gestation.