Vitiligo is a relatively common acquired chronic disorder of pigmentation characterized by the development of white macules on the skin due to loss of epidermal melanocytes .Affecting approximately 0.5%-2% of general population worldwide, without predilection for sex or race.

Lesions may occur in a localized or generalized distribution and may coalesce into large, depigmented areas. Given the contrast between the white areas and normal skin, the disease is most disfiguring in darker skin types and has a profound impact on the quality of life of both children and adults. Generalized vitiligo is the most common clinical presentation and often involves the face and acral regions. The acral and joint areas are common sites of occurrence of vitiliginous lesions, because they are areas subjected to repeated trauma or irritation . The acral lesions are more visible and cosmetically important than lesions at many other sites, causing greater psychosocial distress Acral lesions are usually more resistant to medical management . Several reasons have been put forward, including relatively low melanocyte density; minimal density of hair follicles, which are a melanocyte reservoir; and a greater chance of repeated friction or trauma, which can induce koebnerization. Both acral and joint lesions also tend to be resistant to surgical management . The narrow band-ultraviolet B phototherapy is considered to be a very important modality in vitiligo treatment since its first use in 1997. It was proved to be of higher efficacy, better tolerated, and superior to the other lines of treatment . The prolonged duration of narrow band-ultraviolet B therapy is the main reason for noncompliance, distance to be traveled and monetary, and time loss in attending the hospital at least twice a week for prolonged time were cited as the second common cause for attrition. This clearly increases the need for combined therapy with narrow band-ultraviolet B (NB-UVB) to shorten the duration.

Combined treatments have been found to be superior to monotherapies regarding efficacy, early response and safety, especially in difficult to treat areas and refractory cases .

Platelet-rich plasma (PRP) is an autologous preparation of platelets in concentrated plasma.

Various growth factors, including platelet-derived growth factor, transforming growth factor, vascular endothelial growth factor, and insulin-like growth factor, are secreted from α-granules of concentrated platelets activated by aggregation inducers .

The beneficial effect of platelet rich plasma in vitiligo could be suggested through these growth factors which stimulate keratinocytes and fibroblasts proliferation with subsequent improvement of their interaction with melanocytes leading to the stabilization of melanocytes, it was also found that platelet rich plasma treatment induced accelerated proliferation and migration of fibroblasts through up-regulation of cyclin E and Cyclin- dependent kinase 4, which is important in cell migration and proliferation . Skin micro needling is a technique predominantly used to improve the appearance of cutaneous scarring and photo damage, fine needles puncture the skin, resulting in increased dermal elastin and collagen, collagen remodeling, and thickening of the epidermis and dermis . Additionally, skin needling creates small channels, which increase the absorption of topically applied preparations which has been used in various dermatological treatments.

.Aim of the work:

1. To determine efficacy and safety of automated microneedling + topical platelet rich plasma in combination with narrowband- ultraviolet B in treatment of resistant acral vitiligo.
2. To compare the efficacy of automated microneedling + topical Platelet rich plasma in combination with narrowband ultraviolet B versus automated microneedling and narrowband ultraviolet B only in treatment of resistant acral vitiligo.

Inclusion Criteria:

• Patients older than 18 years.
• Patients with bilateral and symmetrical vitiligo acral in distribution.
• Lesions stable for at least three months.
• Patients receiving topical treatment will be required to undergo two weeks washout period.
• Patients receiving systemic treatment will be required to undergo 1 month washout period.
• Patients who were unresponsive to medical treatment or photo therapy.
• No sex predilection

Exclusion Criteria:

• Haemoglobin< 10 g/dl.
• Platelet count < 105 /UL.
• Patients with active infection.
• Reported histories of koebnerization.
• History of keloid formation or hypertrophic scars.
• Pregnant or lactating females.
• Bleeding tendency.
• Patients with chronic liver diseases.
• Patients using systemic chemotherapy, anti-coagulation therapy and antiplatelet agents.