Oral squamous cell carcinoma (SCC) positive biopsies from patients who underwent excision procedures by micrographical surgery were analyzed by FT-IR microspectroscopy in order to examine a specific fine structure of abnormal epithelial growth - the so-called keratin pearls. Taken from the oral cavity of 15 SCC positive patients, all biopsies indicated poorly or well-differentiated cancer containing smaller and larger pearls. In some cases only a few pearls were present; in others many of various sizes.

After surgery the biopsies were rapidly frozen in liquid nitrogen and stored at -80°C before thin sectioning the tissue for infrared measurements. The frozen tissue was then sliced into 8 μm thin sections and dried on an infrared-transparent Bal2window. For comparison one slice of tissue was always used for hematoxylin and eosin staining by drying it on a standard microscope slide. This procedure creates a series of thin sections on BaF2 and glass following an alternate pattern of one 8 μm section for IR microspectroscopy and the next 8 μm one for microscopy.