Meteorological influences on the incidence of lichen planus in a north Indian population.

Lichen planus is a chronic, autoimmune, mucocutaneous disease that shows differences in clinical presentation at different times of the year. The present retrospective study was conducted to clarify the meteorological factors that influence the incidence of lichen planus, as well as the general features and clinical presentation of this condition during three consecutive years, 2008, 2009, and 2010, in Moradabad district (Western Uttar Pradesh, India). The study group comprised 1,355 patients extracted from the records of the outpatient department of Kothiwal Dental College Research Centre and Hospital, who were clinically diagnosed as having lichen planus during this three-year period. The highest number of patients (735) were recorded in summer, and the lowest (56) in winter. Females were affected more often, and psychosocial influences were also evident. There were significant differences in the incidence of lichen planus in different seasons, and the summer peak was attributable to the intensity of sun exposure (actinic lichen planus and summertime lichen planus).