Microscopic appearance of iatrogenic foreign bodies in neurosurgery

Increased frequency of reoperation in neurosurgery has made the microscopic examination of tissue from previously operated sites more common. Various synthetic materials are in common use in neurosurgery, and these can cause clinical complications as well as presenting a diagnostic dilemma for the pathologist. The microscopic appearance of synthetic materials used by neurosurgeons to aid hemostasis, prevent aneurysm rupture, serve as dural prosthesis and suture wounds is reviewed. The importance of the polarizing microscope in differentiating synthetic materials is emphasized.