Infrared and Raman microspectroscopy of foreign materials in tissue specimens

Infrared and Raman spectra of materials found in tissue specimens submitted for histopathologic diagnosis have been recorded. These foreign materials range in size from approximately 5 to 50 μm, and the vibrational spectra have been used to identify them. Examples include cholesterol and polytetrafluoroethylene (PTFE) in an implant case, polyethylene terephthalate (PET) and polyacrylonitrile (PAN) in a pilonidal cyst, and carbenicillin in a skin biopsy. In some instances, either the infrared or Raman spectra were sufficient to make a definitive identification, while in other cases both were necessary. Because some of the samples fluoresced with visible excitation at 532 nm, FT-Raman spectra with 1064-nm excitation were also recorded. The flexibility of sampling for vibrational microspectroscopy and the value of the recorded data in assisting pathologists render medical diagnoses in the examples cited and other cases are discussed.