Basal cell carcinoma (BCC) in paraffin-embedded specimens was investigated by nondestructively electron paramagnetic resonance (EPR) and X-band (9.45 GHz) EPR imaging (EPRI). A histopathological examination of specimens showed the melanin contents and revealed that they were predominantly of the nodular types. A single-line EPR pattern was observed in the BCC specimens, and the spectra of the samples were analyzed using linewidth and spectral pattern parameters. The eumelanin-related radical was observed in paraffin-embedded BCC specimens. The stability of the radical was supported by sepia pigment experiments. The g-value and peak-to-peak linewidths (ΔHpp) were 2.0046 and 0.61 ± 0.02 mT (mean ± SEM), respectively. Strong EPRI signals correspond to areas of strong pigmentation in the samples. Thus, histopathological examination, EPR, and EPRI of BCC specimens showed that the radical distribution reflects on the spatial distribution of pigments in the samples.
Keywords: BCC; Basal cell carcinoma; EPR; free radical; histopathology; imaging.