الفهرس 
A. VITILIGO
d. The microvascular skin homingOnly 14 pages are availabe for public view
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Abstract
Vitiligo is a specific type of idiopathic acquired or inherited leukoderma, which is characterized by patterned/circumscribed hypomelanosis of the skin & hair, microscopically by complete absence of melanocytes & medically by an increased risk of certain diseases, such as thyroid disease and alopecia areata.
The pathogenesis of vitiligo is contributed to many hypotheses that have been proposed to explain the destruction of melanocytes. But, three principle theories have been presented in this subject, they are the neurogenic, the self-destruct theory & the most approved hypothesis is the autoimmune theory.
The mechanisms underlying the destruction of functioning melanocytes and the absence of melanin in vitiligo lesions remain unclear. Nevertheless, certain theories have been suggested and studied including; the genetic hypothesis, the autoimmune hypothesis, the neural hypothesis (involving neuropeptides, adrenergic and cholinergic neurotransmitters), the apoptotic theory, the viral hypothesis, the self destruction hypothesis (including the significant contribution of oxidative stress through the accumulation of H2O2), and convergence theory (which combines previous theories).
This study aimed at studying the contribution of either the neural mechanism or apoptotic mechanism or both together in generalized and segmental vitiligo variants.
This study included 20 vitiligo patients (11 males and 9 females) divided into groups according to the clinical type into segmental (10 patients; 4 males and 6 females) and non segmental (10 patients; 7 males and 3 females). Their age ranged from 21-35 years with a mean of 27.2 ± 4.3 years. Twenty apparently healthy (especially dermatologically), age and sex matched healthy controls were included in the study. They were10 males and 10 females, and their age ranged from 24-45 years with a mean of 32.6 ± 6.5 years. There was no statistically significant difference between patients and controls as regards age and sex
At presentation, all patients were subjected to detailed history taking, including the family history of vitiligo, complete general and dermatological examination, two biopsies were taken from each patient; one from the depigmented lesional area and the other from the normally pigmented skin at the periphery of the same area. One biopsy was taken from each subject of the control group from sun unexposed skin. Biopsies will be examined for the PGP 9.5 and ssDNA using immunohistochemical staining technique.
A highly statistically significant difference was detected (P<0.01) between lesional and non lesional skins of segmental vitiligo cases as regard PGP9.5 and ssDNA. The same finding was detected between the lesional and perilesional skins of non segmental vitiligo cases.
A highly statistically significant difference between lesional segmental, as well as lesional non segmental vitiligo patients and the control group (p<0.01) was detected regarding PGP9.5 and ssDNA. However to our current state of knowledge, no previous studies where performed on segmental vitiligo and PGP9.5 to support or oppose our findings.
Among all vitiligo cases, a highly statistically significant difference was present between lesional and non lesional skin as regards PGP9.5 (p<0.01).
Among all vitiligo cases, a highly statistically significant difference was present between lesional and non lesional skin as regards ssDNA (p<0.01).
No statistically significant difference between non lesional skin of segmental and non segmental vitiligo patients and the control group was detected regarding the PGP9.5 and ssDNA (p>0.05).
No statistically significant difference between staining intensity of the lesional skin of segmental and non segmental vitiligo cases as regards PGP9.5. while comparing the lesional skin of segmental and non segmental vitiligo cases as regards ssDNA, a high statistically significant difference was detected P<0.01. However to our current state of knowledge, no previous studies where performed comparing on segmental vitiligo and non segmental vitiligo as regards PGP9.5or ssDNA to support or oppose our findings.
Our results showed a +3 staining intensity in 8 lesional vitiligo cases and a +2 staining intensity in 12 lesional vitiligo cases as regards ssDNA as an apoptotic marker, so we could suggest that the apoptotic mechanism is dominantly operating in inducing vitiligo while additional mechanisms could augment the apoptotic mechanism in inducing vitiligo areas one of such mechanisms is the c kit receptors. Intense and moderate staining of ssDNA as an apoptotic marker in all cases highlight the importance of the apoptotic mechanism in inducing vitiligo while additional factors could augment this mechanism.
On comparing staining intensity of the lesional skin of segmental and non segmental vitiligo cases as regards PGP9.5, a non statistically significant difference was detected. while comparing the lesional skin of segmental and non segmental vitiligo cases as regards ssDNA, a high statistically significant difference was detected P<0.01 Both segmental and non segmental vitiligo shares the neural theory, but apoptosis in more evident in the non segmental type.
Finally, on the basis of the increased dermal PGP 9.5-positive nerve fibers and ssDNA-positive (apoptotic) cells we conclude that there is a possible relationship between autonomic nervous system function and apoptosis, supporting the hypothesis that the destruction of functioning melanocytes in vitiligo could be the end result of different interacting pathogeneic mechanisms, such as apoptosis and the accumulation of neural fibers/axon.