Epidemiology of childhood psoriasis: a study of 419 patients from northern India.

BACKGROUND: We undertook this study in order to determine the pattern and prevalence of childhood psoriasis in northern India and to highlight the differences and similarities with previous studies.
MATERIALS AND METHODS: In this retrospective epidemiologic study, the data from 419 children (less than 14 years of age) with psoriasis registered at the Psoriasis Clinic between January 1990 and December 2002 were included.
RESULTS: The 419 children registered at the Psoriasis Clinic constituted 0.3% of the dermatology outpatients and 12.5% of the total psoriasis patients seen over a period of 13 years in the department. There were 219 (52.2%) boys and 200 (47.7%) girls, with a male to female ratio of 1.09 : 1. The age of onset ranged from 4 days to 14 years. The mean age of onset was 8.1 +/- 2.1 years in boys and 9.3 +/- 2.3 years in girls. The peak age of onset in boys was in the 6-10-year age group, whereas the majority of girls showed an onset of psoriasis between the ages of 10 and 14 years. A positive family history was present in only 19 (4.5%) patients. The extensors of the legs were the most common initial site affected [105 (25%) cases], followed by the scalp [87 (20.7%)]. Classical plaque psoriasis was the most frequent clinical presentation [254 (60.6%) patients], followed by plantar psoriasis [54 (12.8%)]. Nail involvement was observed in 130 (31%) cases. All types of nail changes described in psoriasis were seen in these patients. Pitting was the most common nail change, followed by ridging and discoloration. Five children (1.1%) (three girls and two boys) had psoriatic arthropathy. Precipitating factors that brought about the onset of the disease or were associated with exacerbation could be recalled in only 28 (6.6%) patients. Koebnerization was observed in 27.9% of patients. Pruritus was the most frequent symptom, reported by 365 (87.1%) children. Twenty-seven (6.4%) children had other concurrent mucocutaneous diseases (vitiligo, pityriasis alba, alopecia areata, ichthyosis vulgaris, halo nevus, aphthous stomatitis, urticaria, pityriasis versicolor, nummular eczema, salmon patch, and verrucous epidermal nevus). Eighteen children had systemic disorders, including seizures, bronchial asthma, mitral regurgitation, scleroderma, Down's syndrome, high arched palate, cholelithiasis, anterior mongoloid slant, and prognathism; however, these conditions were possibly chance findings only and no correlation with the age of onset or severity of the disease was found.
CONCLUSIONS: Our findings differ from those of previous studies in showing a delayed onset, equal sex distribution, less frequent facial involvement, uncommon guttate lesions, more frequent involvement of the soles, and a less frequent history of familial occurrence.