CURRENT EPIDEMIOLOGY OF LICHEN SIMPLEX CHRONICUS

Background Lichen Simplex Chronicus (LSC) is a common extremely pruritic dermatoses affecting seriously the wellbeing of patients. Although the diagnosis is easily confirmed the therapy is still a challenge for specialists. The aim of the study was to update the epidemiology of LSC. Objective and Methods To assess the tendencies in distribution of LSC were analyzed data collected from registers of Medical Centre “St. Anna” Varna from January 2007 till July 2015. Data include reports of 39968 outpatients with different skin problems. The model of the study was retrospective and investigates the total morbidity, gender distribution, age distribution, peak condition and place of the disease in the structure of selected chronic recurrent dermatoses with negative impact on quality of life. Data were collected and processed after obtaining written permission from the leadership of MC “St. Anna” Varna. Results. The overall frequency of LSC was 4.04%. It increased from 2.59% (2007) to 4.62% (2015). Results show a tendency of rejuvenation of LSH with two peaks of morbidity: over 65 years of age 11.87% and second in the range 25-30 years -10.77%.The the ratio female / male is established to 1.2: 1.The distribution analysis shows the prevalence of LSC in winter season – January 5.14%, February – 4.57% and low morbidity in summer mouths July 1.92% and August 0.66%. (p = 0.001) The distribution of LSC was compared with that of several skin diseases with a chronic course and a negative influence on the quality of life of patients. Results show increasing of LSC from 3.36% (2008) to 4.55% (2014) (p = 0.001). Conclusion This is the first study in our country, which aims to update the epidemiology of LSC.


INTRODUCTION
Lichen simplex chronicus (LSC) is a chronic skin condition occurring as a result of traumatic injury (scratching) of the skin.Constant irritation due to strong and uncontrollable itching formed infiltrated plaques [1].The condition has been estimated to occur in 12% of the popu-lation [2].The highest prevalence is middle to late adulthood, with a peak at 30-50 years.Pathogenesis of this dermatosis is not well distinguished.Disorders of skin barrier are described as a trigger or enhance pathological symptoms of LSC [3].On the other hand, in the pathogenesis of LSC an important role have psychological factors.[4] The dominant symptom in LSC is pruritus.[1] Although LSC is quite common disease with strong impact on quality of patients' life there are not recent studies on its distribution and morbidity.The purpose of this study was to update the epidemiology of LSC.

OBJECTIVE AND METHODS
To assess the tendencies in distribution of LSC were analyzed data collected from registers of Medical Centre "St.Anna" Varna from January 2007 till July 2015.Data include reports of 39968 outpatients with different skin problems.Taking into account the specifics of LSC all patients younger than 18 years of age were excluded and finally observed data include 31 981 dermatologic outpatients.Diagnosis LSC was placed in 1305 cases (4.08%).
Data were collected and processed after obtaining written permission from the leadership of MC "St.Anna"

Varna
The model of the study was retrospective study.We analyzed the total morbidity, gender distribution, age distribution, peak condition and place of the disease in the structure of selected chronic recurrent dermatoses with negative impact on quality of life.
The statistical analysis was performed with SPSS v.21.0 for Windows.Hypotheses were tested using ÷²-criteria (for the descriptive profile data).Results with p<0.001 were interpreted as statistically significant.

RESULTS
Taking into account the specifics of LSC all patients younger than 18 years of age were excluded and finally observed data include 31 981 dermatologic outpatients.Results show the overall frequency of LSC was 4.04%.As 1042 (79.84%) diagnosed in primary visit and 263 (20.16%) during checkup.We observed significant trend of increasing morbidity over the years.As in 2007 morbidity was 2.59 % and in 2014-4.62%(p = 0.002) (Figure 1) The distribution according the gender show the ratio female / male to 1.2: 1 For a period of 102 months 571 ( 54.79% ) female and 471 (45.20%) male at first visit and 141 (53.61%) female and 122 (46.38%) male at checkup were diagnosed with LSH (Table 1)  The results of the comparison of age and gender of the patients show that in younger age groups most of patients are female and this ratio changes with increasing of

Fig. 4. Distribution by months
The frequency of LSC was compared with that of several chronic skin diseases with influence on the quality of life of patients including -seborrheic dermatitis, atopic age in favor of male.In group 25-30 years the ratio female / male is 1.7: 1, and at the age 65 up years, this ratio has been 1: 2.3, which is dominated by male patients.(Figure 3) dermatitis 18up years, lichen planus, eczema.The morbidity of LSC was mean 3.98% with a range of 2.53% for 2007 to 4.55% for 2014.(Figure 5)   Khaitan et al (1999) [9].Relatively large range in incidence of the disease could be explained by the different target groups, who were included in studies.For example Cybulski M. and co-authors (2015) reported that the disease commits 12% of patients, but they study the distribution of skin diseases among elderly patients [10] while we involved patients from different ages.
In a conducted retrospective study we established, significant though slight trend of increasing morbidity over the years (p=0.002).As in 2007 frequency was 2.59%, and in 2014-4.62%.The primary visits were respectively 2.54% for 2007 and 4.55% for 2014, and checkup -4.08% for 2007 and 5.01% for 2014.In literature we did not find such studies, which gives us reason to assume that this is the first study till now.
Many data suggest that the peak of the disease is between 35 and 50 years of age with more prevalent in female than male and the ratio being 2:1[3].Controversially there are data pointing out that LSC is more common in adults, with a peak above 65 years of age at the same distribution by gender.[10] The data obtained in our study showed a ratio of female / male, being 1.2: 1.The distribution by age showed two peaks of the disease: over 65 years of age 11.87% and second in the range 25-30 years -10.77%.The results of the peak of the disease in patients over 65 years correlate with the exported data that LSC is a dermatosis of adulthood.[1, 10,11] In the literature we met no reports of "rejuvenation of the disease."We assume that the peak in the age 25-30 years is due to the increased physical and mental stress, which is one of the major pathogenetic mechanisms of the disease [3].It was further investigated the addiction between age groups and gender of the patients.In younger ages most of patients were female while with the increasing of the age number of male predominated.So in age group 25-30 years the ratio female / male was 1.7: 1, and in age group 65up years this ratio was 1: 2.3.
Results are discussed in the light of other dermatological pathologies which have similar characteristics with LSC.The distribution of LSC compared with that of several skin diseases with a chronic course and a negative influence on the quality of life of patients show increasing of LSC from 3.36% (2008) to 4.55% (2014) (p = 0.001).
The seasonal modulation in LSC should be expected because etiopathogenetic mechanisms of the disease [12,13].Link between skin hydration and cold seasons been known long ago [14] Boulter E.et al (2013) published data on the relationship between homeostasis of skin barrier (corneal layer) and the age and season.[15].Slominski and colleagues (2013) found seasonal variations in hormonal activity [16] Several studies show an increased risk of depression and suicide attempts during the cold seasons and in countries with lower levels of sun [17] .All these data explain established in our study seasonal modulation in LSC.The results showed peak of the disease during the autumn-winter season, and a significant reduction in July and August.Most high percentage was recorded in January an average of 5.14 %, 4.57 % in February and 4.44% in December.Lowest was morbidity in July 1.92% and August 0.66%.

CONCLUSION
Lichen Simplex Chronicus (LSC) is a skin disorder characterized by itching, which seems to have a marked psychological component.The disease is quite common.However, the epidemiological futures are few investigated so far.This is the first study in our country, which aims to update the epidemiology of LSC-including social, demographic, and disease related futures.

Fig. 5 .
Fig. 5.The distribution of LSC in group of similar skin disorders

Table 1 .
Gender distribution