BACKGROUND: The field cancerization concept in photodamaged patients suggests that the entire sun-exposed surface of the skin has an increased risk for the development of (pre)-malignant lesions, mainly epithelial tumours. Topical photodynamic therapy (PDT) is a noninvasive therapeutic method for multiple actinic keratosis (AK) with excellent outcome. OBJECTIVES: To evaluate the clinical, histological and immunohistochemical changes in human skin with field cancerization after multiple sessions of PDT with methyl-aminolaevulinate (MAL). METHODS: Twenty-six patients with photodamaged skin and multiple AK on the face received three consecutive sessions of MAL-PDT with red light (37 J cm(-2)), 1 month apart. Biopsies before and 3 months after the last treatment session were taken from normal-appearing skin on the field-cancerized area. Immunohistochemical stainings were performed for TP-53, procollagen-I, metalloproteinase-1 (MMP-1) and tenascin-C (Tn-C). RESULTS: All 26 patients completed the study. The global score for photodamage improved considerably in all patients (P < 0·001). The AK clearance rate was 89·5% at the end of the study. Two treatment sessions were as effective as three MAL-PDT sessions. A significant decrease in atypia grade and extent of keratinocyte atypia was observed histologically (P < 0·001). Also, a significant increase in collagen deposition (P = 0·001) and improvement of solar elastosis (P = 0·002) were noticed after PDT. However, immunohistochemistry showed only a trend for decreased TP-53 expression (not significant), increased procollagen-I and MMP-1 expressions (not significant) and an increased expression of Tn-C (P = 0·024). CONCLUSIONS: Clinical and histological improvement in field cancerization after multiple sessions of MAL-PDT is proven. The decrease in severity and extent of keratinocyte atypia associated with a decreased expression of TP-53 suggest a reduced carcinogenic potential of the sun-damaged area. The significant increase of new collagen deposition and the reduction of solar elastosis explain the clinical improvement of photodamaged skin.
BACKGROUND: The field cancerization concept in photodamaged patients suggests that the entire sun-exposed surface of the skin has an increased risk for the development of (pre)-malignant lesions, mainly epithelial tumours. Topical photodynamic therapy (PDT) is a noninvasive therapeutic method for multiple actinic keratosis (AK) with excellent outcome. OBJECTIVES: To evaluate the clinical, histological and immunohistochemical changes in human skin with field cancerization after multiple sessions of PDT with methyl-aminolaevulinate (MAL). METHODS: Twenty-six patients with photodamaged skin and multiple AK on the face received three consecutive sessions of MAL-PDT with red light (37 J cm(-2)), 1 month apart. Biopsies before and 3 months after the last treatment session were taken from normal-appearing skin on the field-cancerized area. Immunohistochemical stainings were performed for TP-53, procollagen-I, metalloproteinase-1 (MMP-1) and tenascin-C (Tn-C). RESULTS: All 26 patients completed the study. The global score for photodamage improved considerably in all patients (P < 0·001). The AK clearance rate was 89·5% at the end of the study. Two treatment sessions were as effective as three MAL-PDT sessions. A significant decrease in atypia grade and extent of keratinocyte atypia was observed histologically (P < 0·001). Also, a significant increase in collagen deposition (P = 0·001) and improvement of solar elastosis (P = 0·002) were noticed after PDT. However, immunohistochemistry showed only a trend for decreased TP-53 expression (not significant), increased procollagen-I and MMP-1 expressions (not significant) and an increased expression of Tn-C (P = 0·024). CONCLUSIONS: Clinical and histological improvement in field cancerization after multiple sessions of MAL-PDT is proven. The decrease in severity and extent of keratinocyte atypia associated with a decreased expression of TP-53 suggest a reduced carcinogenic potential of the sun-damaged area. The significant increase of new collagen deposition and the reduction of solar elastosis explain the clinical improvement of photodamaged skin.
Authors: Azza Gaber Antar Farag; Hala Said El-Rebey; Mohamed Abd El-Moneim Shoeib; Shimaa Mohammed Ahmed El-Fiky; Mustafa Elsayed Elshaib; Amal Farid Mostafa Journal: Clin Cosmet Investig Dermatol Date: 2021-06-01