Abscess formation and local necrosis after treatment with Zyderm or Zyplast collagen implant.

The incidence, clinical presentation, pathophysiology, and possible treatment of two rare but clinically meaningful complications of tissue augmentation with Zyderm and Zyplast Collagen Implant are described. Abscesses as a manifestation of hypersensitivity to bovine collagen occur rarely (4 in 10,000 cases) and may persist for days to weeks. Periods of remission and exacerbation may occur from 1 month to more than 24 months. Localized tissue necrosis also occurs rarely (9 in 10,000 cases) after implantation and is probably the result of local vascular interruption and not hypersensitivity. The incidence varies greatly between the anatomic sites of implantation; more than half the reported cases involve the glabella. Evidence strongly suggests that the increased vulnerability of the glabellar region is due to its unique vascular distribution.