Identification of chemical compositions of skin calcified deposit by vibrational microspectroscopies

Calcinosis cutis is characterized by the deposition of calcium salts in the subcutaneous tissues. Both Fourier transform infrared (FTIR) and Raman microspectroscopic analysis have been applied to easily get the chemical compositions of the skin calcified deposit (SCD), which was surgically excised from a female patient. This SCD was cut into two parts for histopathological (H&E stain) examination and vibrational microspectroscopic study. The result indicates that the whole SCD in the skin lesion was found to be a well-developed, mature and hard mass. Several FTIR absorption bands at 873, 961 and 1,031 cm⁻¹ the stretching modes of carbonate and phosphate of hydroxyapatite (HA)], 1,547 and 1,658 cm⁻¹ (the amide I and II bands of collagen) were detected in the IR spectrum of SCD. The Raman spectral bands at 1,665 and 1,450 cm⁻¹ (collagen); 1,519 and 1,156 cm⁻¹ (β-carotene); and 1,072 and 958 cm⁻¹ (HA) were also obtained. To our knowledge, this is the first report using FTIR and Raman microspectroscopies to quickly identify and quantify three predominant components, collagen, β-carotene and type B carbonated HA, in the SCD of a patient.