VITILIGO is believed to be an immune mediate disorder affecting skin.
It is characterized by depigmented spots with sharp well defined margins bilateral in most of the cases , usually patches appears on exposed parts, extremities, body orifices , most common sites involved are hand,wrist, lips, face, feet, umbilicus, eye lids, nostrils mucosa of nose eye and mouth are also involved.
PATHOGENESIS and GENETICS
Its cause is not known, but it’s believed to be multifactorial disease which is genetically predisposed and triggered by Environmental factors. It is frequently accompanied by other autoimmune conditions like Hashimoto’s thyroiditis, psoriasis, systemic lupus erythematoses, pernicious anaemia, alopecia areata etc.It is a non infectious condition. A strong hereditary association is noted.
Tyrosinase the enzyme of melanocyte expressed by TYR gene which is not the component of immune system but catalyzes melanin synthesis and is a major autoantigen in generalised vitiligo. A genomewide dtudy have found around 36 loci associated with succeptibility towards generalised vitiligo, its usually due to defect in genes related to melanocytes or immune system , its doubted that there might be some autoimmune response towards melanocytes.
SYMPTOMS AND CLASSIFICATION
It can be classified into segmental and nonsegmental types
In nonsegmental type the depigmentation appear somewhat symetrical and bilateral and usually grow with time and also appears in new areas with somewhat symetrical pattern it can start at any age and can grow to generalised vitiligo or vitiligo universalis where very few normal pigmented patches are left behind.
It is further categorised into
Vitiligo Universalis depigmented patches cover almost whole body with very few patches of normal pigmented patches are left behind , Micheal Jackson suffered from this type.
Generalised Vitiligo depigmented patches scattered throughout the body in somewhat symeterical fashion.
Focal Vitiligo one or few small patches in an area, commonly found in children.
Acrofacial vitiligo only fingers and periorificial areas involved
Mucosal Vitiligo only mucosal membranes involved
Segmental type usually affects segments of skin supplied by dorsal root from spinal cord. its usually nonsymetrical and unilateral, it is less frewuently associated with other autoimmune disorders as compared to segmental type, it usually is stable and static and does not grow much in size eith time.
When patches of affected skin are exposed to UV-A light it glows blue and the normal unaffected skin shows no reaction
Biopsy helps in confirmation of diagnosis