the exact prevalence of psoriasis , vitiligo and atopic dermatitis ( ad ) in india is not known and we rely on western data . the information on prevalence would be useful for planning strategies to manage these diseases . this point prevalence study was undertaken to determine the epidemiological pattern of psoriasis , vitiligo and ad in india . to conduct a proper epidemiological study a huge amount of money and trained manpower even door - to - door survey can have limitations since all the occupants may not be available and information regarding the occupants may not be revealed . in the light of above situation the study was conducted in four zones of india namely north , south , east and west . an invitation letter to join the study was sent to all the medical colleges in india having a dermatology postgraduate programme through post and email . one college from each zone that had volunteered for the study was randomized by lots . a common profoma was sent to the selected medical colleges , one in each zone . , the details regarding dermatology outpatients and also the total number patients attending hospital was collected simultaneously . the data regarding the patients with psoriasis , vitiligo and ad was collected as per the proforma . medical college selected by random method from each zones were aiims , delhi ( north zone ) , vss medical college , odisha ( east zone ) , svs medical college , mahabubnagar ( south zone ) and byl nair ch . there were 4785 cases registered in the outpatient departments of the four hospitals on 20 november 2012 and 443 cases were registered for dermatology consultation . the point prevalence of psoriasis , vitiligo and ad among dermatology diseases were 8.002% , 9.98% and 6.75% respectively [ table 1 ] . point prevalence and sex ratio of psoriasis , vitiligo and atopic dermatitis among the psoriasis patients , the ratio of male to female was 1.1:1 . highest prevalence was noted in the age group of 21 - 30 and 41 - 50 years , comprising 25% each [ table 2 ] . the most common sites of involvement in descending order of frequency were the palms and soles ( 33% ) and scalp ( 20.8% ) . age distribution among psoriasis and vitiligo patients the male to female ratio among vitiligo patients was 1:1.8 . highest point prevalence of vitiligo was found among 11 - 20 years of age group , comprising 26.08% . indian academy of dermatology , venereology and leprosy task force on vitiligo has defined stability of vitiligo as a patient reporting no new lesions , no progression of existing lesions and absence of koebner 's phenomenon during the preceding one year . in our study , lower lip involvement was present in 75% of patients and both lips were involved in 41% . the site of onset was the lower limb ( 43.47% ) , upper limb ( 15.21% ) , face ( 15.21% ) abdomen ( 13.04% ) , back ( 4.34% ) , chest ( 2.17% ) and breast ( 2.17% ) . positive family history was found in 17.39% patients of vitiligo , among them the first - degree relatives ( parent / brother / sister / son / daughter ) accounted for 50% and second - degree relatives ( grandparent / maternal and/or paternal uncle or aunt ) accounted for the remaining 50% . personal history of atopy was present in ( 59.5% ) patients , who mostly had allergic rhinitis followed by conjunctivitis and bronchial asthma . family history was present in 37.03% of patients of which 60% were of the first generation and 30% of the second generation . psoriasis is a common disorder in which environmental factors contribute to the development of sharply demarcated erythematous scaly plaques in genetically predisposed individuals . from the available studies , the prevalence of psoriasis in india ranges from 0.44 to 2.8% . the high prevalence rates in our study may be due to the study being conducted during winter . bedi reported a positive family history of psoriasis in 14% of their patients which is similar to our study 12.5% . vitiligo is a commonly acquired , idiopathic , heritable depigmentary disorder of the skin and/or mucous membranes . the point prevalence of vitiligo was 9.982% in our study compared to that by handa and kaur , where the relative prevalence varied between 0.46 and 8.8% . the cause of female preponderance is probably because of greater cosmetic awareness and the impact of the disease on their social life . koranne et al . stated that in india , family history ranged from 6.25% to 18% , which is similar to our reported figures . younger people were more frequently affected and had active vitiligo compared to older people . early onset and generalized vitiligo ( 56.52% ) was the most common type followed by acrofacial and other types . . and sarin et al . also reported generalized vitiligo to be more common in their studies . lower limbs were the most common site of onset in 43.47% of patients in this study irrespective of the clinical type of vitiligo , similar to studies by to shajil et al . this could be because of larger body surface area of lower limbs compared to upper limbs . ad is a chronic relapsing eczematous skin disease characterized by pruritus and inflammation and accompanied by cutaneous physiological dysfunction , with a majority of the patients having a personal or family history of  atopic diathesis . the prevalence of atopic eczema in 56 countries had been found to vary between 3 and 20.5% . in our study in contrast to children in north india , only 0.01% ( 3 out of 2100 ) children in a south indian study had ad . even in our study , the flexural involvement in our study was found in 48.14% of atopic patients , similar to another study . in our study , dry skin was found in 92.5% of ad at the time of presentation . the changed lipid content and personal and family history of atopy was observed in 59.25% and 37.03% respectively . in another study , the personal and family history of atopy was observed in 54% and 65% , respectively . itching was present in 96.2% of patients at the time of presentation . itching in ad is caused by central and peripheral neural sensitization , impaired barrier function , itch scratch cycle and various mediators including serine proteases , interleukin 31 and nerve growth factor . the point prevalence of psoriasis , vitiligo and ad were 8% , 9.98% and 6.75% respectively . our data correlates with previous hospital - based prevalence studies of psoriasis , vitiligo and ad . the limitation of our study is that it is not the exact prevalence in the community since it was a hospital - based study . hence more detailed community based epidemiological studies need to be done to know more about the disease course and clinical patterns that vary in different individuals .
background : the knowledge of the prevalence of common dermatoses will be useful for optimum use of valuable resources of the country.aim:the aim of the study is to determine the pattern and prevalence of psoriasis , vitiligo and atopic dermatitis ( ad ) in india.materials and methods : this was a hospital - based study conducted on a single day in one medical college each in four zones of india.results:the point prevalence of dermatological cases was 9.25% . 
 the point prevalence of psoriasis , vitiligo and ad were 8% , 9.98% and 6.75% respectively . 
 chronic plaque type psoriasis was the most common ( 50% ) clinical pattern . 
 the most common site of involvement of psoriasis was the palms . 
 stable type of vitiligo was common which accounted for 65.21% . 
 lower lip was involved in 75% of mucosal vitiligo . 
 lower limbs were the most common site of onset of vitiligo . 
 ad was most prevalent in the first decade ( 40.7% ) . 
 personal history of atopy was present in ( 59.5% ) patients . 
 dry skin was present in 92.5% of patients.conclusions:our data correlates with previous hospital - based prevalence studies of psoriasis , vitiligo and ad .