الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Background: Vitiligo is a pigmentary disorder where the loss of functioning melanocytes causes the appearance of white patches on the skin . Vitiligo affecting hand and foot (acral vitiligo) is known to resist repigmentation by conventional lines of treatment as well as surgical interventions compared to non acral vitiligo. Transmission electron microscopy (TEM) permits the observation of fine intracellular structures beyond that seen with light microscope. Aim of this work: to study ultrastructure of melanocytes and keratinocytes within acral and non acral perilesional (PL) skin lesions, in an attempt to clarify why acral vitiligo lesions remain resistant to all types of treatments compared to non acral lesions in the same patient. In addition ,it aims to identify ultrastructural changes that may occur after NB-UVB in acral versus non acral PL vitiligo. Results & conclusion: Ultrastructural differences were found when acral was compared to non acral skin. In acral skin, melanocytes showed less density, more degeneration (nuclear changes ;pyknosis, peripheral chromatin condensation ,and cytoplasmic changes;vacuoles) compared to the non acral PL skin before and after treatment by NB-UVB. This indicates lower quality and quantity of melanocytes in acral skin compared to non acral PL both before and even after treatment. Also, shows impaired motility of melanocytes with less & short dendrites. Keratinocytes (KCs) as well showed more signs of degeneration(nuclear changes ;pyknosis, peripheral chromatin condensation , widening of inter keratinocytes spaces , deposition of extacelluar granular materials(EGM) and cytoplasmic changes;vacuoles) in acral PL compared to non acral PL. After NB- UVB, improvement in melanocytes occur in both acral and non acral PL with more improvement in non acral PL skin. In keratinocytes, more consistent improvement of keratinocytes occur only in non acral PL skin. All these differences may account at least partially for acral resistance to treatment.