Document Type : Original Paper
Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Department of Anatomy, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
Department of Pathology, Faculty of Veterinary Medicine, Semnan University, Semnan, Iran
Introduction: Exposure to ultraviolet (UV) radiation causes oxidative damage and cancer in the epidermis. The thickening of the skin layer seems to be correlated with carcinogenicity. The present study aimed to induce trichoepithelioma, a rare benign skin lesion, in an animal model and investigate the relationship between the radiation dose of UV waves and the thickening of skin layers resulting from high-frequency ultrasound images.
Material and Methods: To investigate skin damage process, 25 C57BL6 mice were irradiated with Ultraviolet B-rays (UVB) (5 times a week for 9 weeks) with an energy density of 135, 270, 405, 540, 675, 810, 945, 1080, and 1215 J/m2, from the first week to the ninth week, respectively. The thickness of the skin layer was weekly measured by ultrasound images. The correlation between the thickness of the skin layer and the radiation energy density was analyzed by Pearson correlation analysis.
Results: The thickness of the skin layer demonstrated a significant increase in the 7th week of exposure during the injury process due to UV radiation, as compared to zero-day (P˂0.05). Furthermore, it showed a 38 % increase in the 7th week. The obtained results illustrated a significant correlation coefficient of more than 0.97 between the thickness of the skin layer and the energy density of UV radiation. Microscopic sections in the long-term UV-irradiated group confirmed trichoepithelioma.
Conclusion: As evidenced by the obtained results, prolonged irradiation for 9 weeks induced an animal model of trichoepithelioma.