Role of Chronic Sun Exposure in the Proliferative Activity of Acquired Melanocytic Nevi
Journal of Pan-Arab League of Dermatologists
Vol. 18, No. 2, June 2007 Page 25- 35
Role of Chronic Sun Exposure in the Proliferative Activity of Acquired Melanocytic Nevi
Mohamed A El-Khalawany*, Amany Abd El-Hameed**
Departments of Dermatology & Venereology**, Al-Hussein University Hospital, Al-Azhar University and Pathology**, National Cancer Institute, Cairo University, Egypt
Abstract
Background: It is well known that sun exposure is a major risk factor in the development of both melanocytic nevi and malignant melanoma, and the possible transformation of melanocytic nevi into malignant melanoma becomes established by many previous studies supported by the pathological coexistence of both tumors in the same lesion.
Objective: Our purpose was to study the effect of chronic sun exposure on the proliferative activity of common (acquired) melanocytic nevi aiming to assess the possibility of malignant transformation of these nevi among Egyptian population.
Methods: Eighty six patients presented with acquired melanocytic nevi were selected and classified into two groups (A and B). In group A (n = 44) the lesions were located in sun exposed areas while in group B (n = 42) the lesions were situated in sun-protected areas. Histopathological examination and immunohistochemical staining with the proliferating marker Ki-67 (MIB-1 MoA) was performed for all cases in addition to 14 cases of cutaneous melanoma.
Results: The mean proliferation index (PI) of melanoma group was 7.2 ± 2.2 while in group A (sun exposed nevi) the mean PI was 0.78 ± 0.53, and in group B (sun protected nevi) it was 0.53 ± 0.24. The melanoma group showed highly significant elevation than both melanocytic groups (p < 0.0001). Also, there was a borderline significant elevation of PI in sun exposed nevi than sun protected nevi (p = 0.05). In both melanocytic groups the PI of compound nevi was more than junctional and intradermal nevi and this was more prominent among old aged (>40 years) with nevi more than 10 years duration.
Conclusion: The proliferative activity of acquired melanocytic nevi is much lower than that of malignant melanoma and there is no need to remove these nevi in order to minimize the likelihood of malignant transformation. Chronic sun exposure, old age, long duration, fair skin and male gender were found as risk factors that associated with the highest proliferation index of compound melanocytic nevi with potential risk of malignant transformation.
Journal of Pan-Arab League of Dermatologists
Vol. 18, No. 2, June 2007 Page 25- 35
Role of Chronic Sun Exposure in the Proliferative Activity of Acquired Melanocytic Nevi
Mohamed A El-Khalawany*, Amany Abd El-Hameed**
Departments of Dermatology & Venereology**, Al-Hussein University Hospital, Al-Azhar University and Pathology**, National Cancer Institute, Cairo University, Egypt
Abstract
Background: It is well known that sun exposure is a major risk factor in the development of both melanocytic nevi and malignant melanoma, and the possible transformation of melanocytic nevi into malignant melanoma becomes established by many previous studies supported by the pathological coexistence of both tumors in the same lesion.
Objective: Our purpose was to study the effect of chronic sun exposure on the proliferative activity of common (acquired) melanocytic nevi aiming to assess the possibility of malignant transformation of these nevi among Egyptian population.
Methods: Eighty six patients presented with acquired melanocytic nevi were selected and classified into two groups (A and B). In group A (n = 44) the lesions were located in sun exposed areas while in group B (n = 42) the lesions were situated in sun-protected areas. Histopathological examination and immunohistochemical staining with the proliferating marker Ki-67 (MIB-1 MoA) was performed for all cases in addition to 14 cases of cutaneous melanoma.
Results: The mean proliferation index (PI) of melanoma group was 7.2 ± 2.2 while in group A (sun exposed nevi) the mean PI was 0.78 ± 0.53, and in group B (sun protected nevi) it was 0.53 ± 0.24. The melanoma group showed highly significant elevation than both melanocytic groups (p < 0.0001). Also, there was a borderline significant elevation of PI in sun exposed nevi than sun protected nevi (p = 0.05). In both melanocytic groups the PI of compound nevi was more than junctional and intradermal nevi and this was more prominent among old aged (>40 years) with nevi more than 10 years duration.
Conclusion: The proliferative activity of acquired melanocytic nevi is much lower than that of malignant melanoma and there is no need to remove these nevi in order to minimize the likelihood of malignant transformation. Chronic sun exposure, old age, long duration, fair skin and male gender were found as risk factors that associated with the highest proliferation index of compound melanocytic nevi with potential risk of malignant transformation.