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العنوان
CLINICAL AND DERMOSCOPIC charACTERISTICS OF MELANOCYTIC NEVI IN PREPUBERTAL CHILDREN \
المؤلف
sayed, Asmaa Abd El-Hameed Mohamed.
هيئة الاعداد
باحث / Asmaa Abd El-Hameed Mohamed sayed
مشرف / Hoda Ahmed M. Moneib
مشرف / Khaled M. Abd El-Raouf El-Zawahry
تاريخ النشر
2015.
عدد الصفحات
236 p. :
اللغة
الإنجليزية
الدرجة
ماجستير
التخصص
الأمراض الجلدية
تاريخ الإجازة
1/1/2015
مكان الإجازة
جامعة عين شمس - كلية الطب - Dermatology, Venereology and Andrology
الفهرس
Only 14 pages are availabe for public view

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Abstract

Dermoscopy is a non-invasive technique that allows physicians to observe structures and colors not otherwise visible to the unaided eye. The conventional dermoscopic diagnosis is based on the assessment of specific criteria and on the application of different diagnostic algorithms. In recent years, polarized light dermoscopes gradually overtook non-polarized light devices. Dermoscopy is not too time-consuming. The time for dermoscopic examination of nevi is basically double that required for a naked-eye examination, but still under 3 minutes that is a reasonable time for a correct skin cancer screening and reduces the number of unnecessary biopsy.
Dermoscopy also allows us to study the physiology of nevi. Some people have a high propensity to develop nevi, others lower, and this propensity is genetically established and, in part, due to environmental factors. The number of nevi is small in childhood, increases during adolescence and mid-life, and finally decreases during late adulthood. The dermoscopic pattern of nevi seems to be age- and site related.
Children, like their adult counterparts, often present to the dermatologist with pigmented lesions that are new or changing. Unique to the pediatric population, however, is that they are in a dynamic growing phase of life. One sign of this dynamic phase is manifested by the development, growth, and occasional involution of nevi.
Although there are many different classification schemes depending on the method to obtain the morphologic information, the most widely used scheme divides melanocytic nevi according to their clinical history into congenital and acquired nevi.
By definition, congenital melanocytic nevi are present at birth or soon thereafter, although some small congenital nevi are clearly tardive in their clinical presentation. Current opinion holds that some elements of such nevi are present at birth but remain inconspicuous until some later date.
Based on the definition of a congenital nevus, the group of acquired nevi encompasses basically all other benign melanocytic proliferations with development after birth. In contrast to congenital nevi, not the size but the number and clinical variability of acquired nevi are the most important risk factors for the development of melanoma.
Furthermore, considerable confusion arises in differentiating small congenital nevi from acquired nevi as many nevi with histopathologic criteria suggestive of small congenital nevi are actually not present at birth.
Currently, there are different classification schemes that are dependent on the method of obtaining morphological information. While clinical (non dermoscopic) classification involves flat, elevated and nodular types, dermoscopy identifies globular, reticular or structureless morphologies, with various combinations of these features as subtypes.
Briefly, the new concept states that nevi develop via two different pathways, namely an endogenous (origin from dermal melanocytes) and exogenous (origin from epidermal melanocytes) pathway. The former leads to nevi that develop in early childhood and persist throughout a person’s lifetime, revealing a dermoscopic globular pattern, while nevi with an epidermal origin develop mostly at puberty due to exogenous factors, such as UV exposure, and show a dynamic life-cycle. These latter nevi exhibit a reticular pattern by dermoscopy.
The most significant difference between the new and traditional classification of nevi is that-with the exception of large and intermediate size congenital nevi-the new classification no longer differentiates between nevus types based on history. Instead, nevi are summarized into categories based on common epidemiological and morphologic features. Basically, five main categories can be differentiated, which are globular, reticular, mixed (complex), starburst, and structureless blue pattern, of which each corresponds to specific histopathologic substrate. Besides these main groups, the dermoscopic classification further distinguishes between three specific subgroups, which are nevi of special body sites (including facial, acral, and subungual nevi), nevi with special features (halo nevus, Meyerson nevus, traumatized targetoid, hemosiderotic nevus, cockade nevus, combined nevus, and recurrent nevus), and unclassifiable melanocytic proliferations.
The present study included 213 Egyptian children with a total number of 403 melanocytic nevi <1.5 cm in diameter. Their age was under twelve. 126 were girls and 87 were boys. Girls showed higher prevalence of nevi and this may be due to the increased number of girls involved in the study. Most of the detected nevi were in children above 6 years thus the nevi count increasing with age. Although Most of lesions were belonging to skin phototype III, the frequency of nevi will be higher if we examined the same number of skin type II children.
In this thesis, we evaluated the clinical types of melanocytic nevi and we found that junctional nevi were the most common clinical type in the examined children (86%), while (14%) only were of the compound type. Intradermal type is not detected at all in them as expected for nevi at the beginning of their natural history.
In our study, there is no single dermoscopic pattern can be considered the predominant pattern as the complex, pseudonetwork, reticular and globular patterns were nearly as frequent as each other. Excessive sun exposure in the Egyptian children may be a contributing factor in the development of the reticular pattern at that age.
According to the correlation between the dermoscopic pattern and skin phototype we concluded that the Pseudonetwork and reticular pattern were more common in skin type III which is the most common skin phototype among Egyptian children.
Nevi with central hypopigmentation wasn’t found as no one of the involved children was skin type I, while skin type III & IV were characterized by other patterns e.g. reticular, globular and complex pattern especially the reticulohomogenous pattern and the homogenous part was central hyperpigmentation specifically.
We also noticed that reticulation in the background was associated not only with reticular pattern but also in a small portion of the globular pattern.
We also evaluated the relation between the dermoscopic pattern and location of nevi in the body and we found that the reticular pattern is located commonly in the trunk (n = 31) and the upper limb (n = 30) while the globular, complex and homogenous patterns are located more in the head & neck region (n=32), (n= 27), (n=8) respectively. Thus, globular nevi display an anatomical distribution compatible with the embryonic cephalad-to-caudal and axial-to-peripheramelanoblast migration sequence.
In conclusion, our study demonstrates that individuals display a morphological type of nevi in relation to their age. The dermoscopic pattern of nevi seems to be age- and site related. Awareness of age-related differences in the dermoscopic patterns of nevi might lead to a more accurate evaluation and management of melanocytic skin lesions that exhibit unusual dermoscopic patterns. For example, some new globular ‘banal’-appearing nevi in adults may represent melanoma lacking melanoma-specific dermoscopic criteria. Furthermore, the observations made in this study raise interesting questions regarding nevus evolution and pathways responsible for nevogenesis. Ultimately, the correct classification of nevi may help better define populations at higher risk for developing melanoma.