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ORIGINAL ARTICLE
Year : 2022 | Volume
: 42
| Issue : 2 | Page : 97-102
Prevalence and risk factors associated with acanthosis nigricans in primary school children
Noha E. Mohamad MD 1, Samar M.R. El-Tahlawy2, Naglaa A. El Sherbiny3, Eman S. Ebrahim1
1 Department of Dermatology & STD and Andrology, Fayoum University, Fayoum, Egypt
2 Department of Public Health & Community, Fayoum University, Fayoum, Egypt
3 Department of Dermatology, Cairo University, Cairo, Egypt
Correspondence Address:
Noha E. Mohamad
Department of Dermatology and Venereology, Faculty of Medicine, Fayoum University, Keman Faress, Fayoum 39111
Egypt
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/ejdv.ejdv_16_21
Background Acanthosis nigricans (AN) is characterized by pigmented velvety thickening of the intertriginous body areas and neck. Many studies linked it to metabolic syndrome.
Aim To detect the prevalence of AN among primary school children and to identify the associated risk factors.
Patients and methods We included 2060 primary school students who were selected from two rural and four urban schools. The data were collected by questionnaire sheets that were fulfilled from each student in which present and past history for any disease were taken.
Results The prevalence of AN was 17.7% of all examined students, higher in females (18.6%) than males (16.3%), but it was not statistically significant. More than half of the students 55.0% were of normal weight, 23.3% were overweight, and 21.7% were obese. In the current study, 69.1% of obese children were having AN.
Conclusions Regular dermatologic examination for early identification of AN is required. AN in the knuckles should be considered as a classic site and highly prevalent. It should be borne in mind that coordinated efforts of medical professional teams may be required aiming to correct the underlying disease to improve the skin symptoms. Strict follow-up of patients with AN for early detection and management of insulin resistance and metabolic syndrome.
Keywords: acanthosis nigricans, prevalence, primary school children
Acanthosis nigricans (AN) is asymptomatic dermatosis manifested as velvety, brownish-black, hyperkeratotic plaques, typically affecting the intertriginous surfaces and neck [1]. AN recognition should prompt the clinician to further evaluate the patient clinically to determine the underlying cause, which may be benign (obesity related, hereditary, or endocrine) or malignant [2].
AN frequency is often underestimated commonly seen in middle aged or elderly, but recently, an increase in the childhood cases is reported [3]. AN has no known sex predilection. An Indian study found that 77.8% were females versus 22.2% for males [3].
Flexural distribution of AN can be caused by mechanical factors having an important role in keratinocyte proliferation. Other areas involved are conjunctiva, eyelids, lips, elbows and knees, knuckles, external genitalia, areolae, and anus. In some cases of malignancies, AN may affect oral cavity, esophagus, nose, or larynx [4].
AN types included obesity-associated AN, syndromic AN, malignant AN, unilateral AN, acral AN, drug-induced AN, and mixed AN [5].
The most frequent form is obesity-associated AN whose course is often slowly reversible after weight loss. It is more common in overweight patients with insulin resistance (IR) [3]. AN has been demonstrated now as a reliable marker for IR in children and adolescents with obesity [6]. There is no specific treatment for AN. It should be borne in mind that coordinated efforts of medical professional teams may be required aiming to correct the underlying disease to improve the skin symptoms.
AimThe aim of this work was to estimate the prevalence of AN among primary school children with identification of the associated risk factors.
Patients and methodsStudy design
This was a cross-sectional descriptive study conducted in Dermatology and Venerology Department, Faculty of Medicine, Fayoum University.
Sample size and type
In total, 2060 primary school children were included, they were selected according to their geographical distribution from two rural (public) and four urban (two public and two private) primary schools in Fayoum governorate; during the period from March 2019 to May 2019.
Study population and subtypes
The study population was primary school students, from both public and private schools. It consisted of children attending two private schools (600 children), children from two public schools in an urban area (700 children), and children from two public schools in a rural area (760 children) with a total of 2060 students.
In each school, student patients were chosen aged 9–12 years attending fourth, fifth, and sixth grades of primary schools to be easy in answering the questions with proper clinical examination. All the students’ classes were enrolled after official and parental approval was granted.
Study questionnaire: the items included name of the studied patients, ages, sex, residence, family history, food habits, parents’ education, and occupation and lifestyle.
Ethical consideration
This study was reviewed and approved by the Faculty of Medicine Research Ethical Committee. The study was conducted after explaining the aim of the study and confidentiality was expressed to the students and their parents. Verbal consents were taken from the class teacher and students before examination. The method of clinical examination was explained to students with the help of a social worker or class teacher and conducted in a previously prepared room. Treatment was prescribed when indicated and the method of use was explained.
Study tools
Structured questionnaire with close-ended questions includes the following:
Sociodemographic aspects such as age, sex, residency, father and mother education, and father and mother occupation.The predisposing factors such as diet habit, behavioral factor in the form of watching television, and physical activity in the home and at school.The full history (present and past) related to the skin lesion such as onset, course, duration and relapse or complication, and family history of the lesion.Clinical examination of all students
All students underwent a detailed physical examination, including anthropometry (height, weight, waist circumference, and BMI). The waist-to-height ratio was calculated to assess central obesity. All the measurements were taken twice and the mean of the readings was recorded. Fitzpatrick skin phenotype was also done. Neck severity and neck-texture severity was assessed using the Burke’s quantitative scale [7] for AN, other anatomical sites were chosen to assess the presence and extent of AN, including the axilla, knuckles, elbows, knees, other intertriginous areas, and general overview on the rest of the body. The patients were asked about the onset, course and duration of the disease, affection of other family members, and if there were any associated symptoms with the lesion.
Statistical analysis
Data were collected and coded to facilitate data manipulation and double entered into Microsoft Access and data analysis was performed using SPSS software; software statistical computer package version 22 (SPSS Inc., USA), version 18 under Windows 7. Simple descriptive analysis in the form of numbers and percentages for qualitative data, and arithmetic means as central-tendency measurement, SDs as a measure of dispersion for quantitative parametric data, and inferential statistic test. Independent Student t test was used to compare measures of two independent groups of quantitative data. χ
2 test to compare two of more than two qualitative groups. The level of P value less than 0.05 was considered the cutoff value for significance.
ResultsThe study population was distributed as follows: most participants 1460 (70.9%) were selected from public schools, while 600 (29.1%) attended to private schools. The age ranges from 9 to 12 years old, more than half of the children 57.8% (N=1191) were females and 42.2% (N=869) were males. According to residence of students, most of them 63.1% (N=1300) inhabited urban areas and 36.9% (N=760) inhabited rural areas. The prevalence of AN, according to a quantitative scale of AN, was 17.7% with 95% confidence interval (CI) of 16.0–19.3%. There was a statistical significant association between prevalence of AN and type of school (P<0.0001). The prevalence rate of AN in private school children (22.7%) was found to be higher than among those in public schools (15.6%) ([Table 1]).
Table 1 Relation between demographic characteristics and acanthosis nigricans prevalence among study childrenAs regards educational level, there was no statistical significant association between the prevalence of AN among children and educational status of their fathers. In contrast, there was a statistical significant association between the prevalence of AN among children and educational status of their mothers. AN was more common in children whose mothers completed the university education [prevalence rate=21.6%, odds ratio (OR)=1.977, 95% CI: 1.064–3.673, P=0.031]. With the same manner, mother’s occupation was significantly associated with the prevalence of AN. The prevalence rate in children whose mothers were working in professional occupations was found to be 21.0% (OR=1.404, 95% CI: 1.081–1.824, P=0.011) followed by 17.0% (OR=1.084, 95% CI: 0.811–1.450, P=0.585) for employees as compared with workers (prevalence rate=15.9%) ([Table 2]).
Table 2 Relation between socioeconomic characteristics and acanthosis nigricans prevalence among study childrenAs regards to food habit, it was statistically significantly related with AN prevalence with high prevalence of AN among students who eat junky food (prevalence rate=21.8%, OR=4.006, 95% CI: 2.797–5.738, P<0.0001) compared with who eat healthy food (6.6%), as shown in [Table 3].
There was a statistically significant positive correlation between the quantitative scale of AN and different study parameters as in [Table 4].
According to family history, about one-third (30.2%) of cases had family history of obesity followed by 10.2% of cases that had family history of diabetes mellitus, 8.5% of cases had family history of AN, 1.1% of cases had family history of hypertension, and 6.0% of cases had family history of other diseases.
According to the anatomical site of AN, the neck was affected in near 100% (95.6) of cases followed by knuckles of fingers (37.4%) and hands (35.2%), and then axilla (14.2%). Regarding neck grading, grade 2 represented 40.9% (N=149) of AN cases ([Table 5]).
Students with AN spend more time watching TV than those without AN (1.7±0.5 vs. 1.4±0.6), which was statistically significant (P<0.0001), also, there was a statistical significant association between the prevalence of AN and activity. Prevalence of AN was higher in children with sedentary lifestyle (prevalence rate=34.9%, OR=9.225, 95% CI: 5.235–16.257, P<0.0001) and active children (prevalence rate=15.9%, OR=3.262, 95% CI: 1.902–5.593, P=0.0001) as shown in [Figure 1].
Figure 1 Relation between the level of activity and prevalence of AN. AN, acanthosis nigricans. Discussion The current study found that the prevalence of AN was 17.7% of all examined students, which was lower than the findings from studies conducted in Brazil (76%), United States (74%), and Mexico (64.2%), but higher than those found in Saudi Arabia (14.1%) [8]. Obesity-associated AN was the most prevalent in our study (90.9%) followed by familial AN (9.1%). This was in agreement with a study conducted by Koh et al. [9], who found that the majority was obesity-associated type. On the same line with the various international studies, which found the prevalence of AN in obese children or adolescents ranged from 49.2 to 58.2% [10]. In our thesis, 4.6% of overweight children had AN and 69.1% of obese children had AN, which agreed with a study carried on 74 obese pediatric patients who attended the Department of Pediatrics at Chosun University Hospital in Korea, which found that AN was observed in 56 (75.7%) patients, but still, our study has a higher ratio regarding sample size [9]. Obesity is commonly associated with IR. Insulin and insulin-like growth factor-1 and their receptors are incorporated into complex regulation, resulting in epidermal hyperplasia [11].
Our study showed a positive correlation between the severity of AN and different variables, including age, weight, height, waist circumference, BMI, and BAZ (BMI- for age Z scores). Older children had a longer duration of being obese and having IR. This was in agreement with a study carried out in a tertiary care hospital in Pune, Maharashtra, in which the severity (grades) of AN correlated with increasing BMI and waist circumference [12].
According to family history, about one-third (30.2%) of cases had family history of obesity followed by 10.2% of cases that had family history of diabetes mellitus, 8.5% of cases had family history of AN. This may be due to genetic predisposing factors. This was in agreement with a study conducted at two university children hospital outpatient centers, in Simferopol, Ukraine, and in Heidelberg, Germany [13].
Females having AN were higher in our study (18.6%) than males (16.3%), but this was not statistically significant. This may be due to the relative higher number of females in our sample. On the same line, a study conducted in New Mexico found no sex predilection for AN. On the contrary, a study conducted in India showed the sex distribution of AN, 77.8% were females [3].
The current study found that the prevalence rate of AN in urban school children (22.7%) was higher than in rural schools (9.1%). The area of living, either urban or rural, might have an impact on nutrition and health status because of changes in the lifestyles and dietary habits. This was in disagreement with a study conducted on 392 of Palestine children aged 2–18 years [14]. Obesity-associated AN showed less activity, sedentary life, and dietary junk food. Sedentary lifestyle is associated with junk food with subsequent obesity. This was in line with a study carried out in a tertiary-care hospital in Pune, Maharashtra, in which sedentary lifestyle, physical inactivity, and change in dietary habits were the same risk factors [12].
This study found higher prevalence of AN in students who reach school by bus (23.0%) than those who walk to school (12.2%), due to lack of activity and low-energy loss. This was in disagreement with a study conducted in Hebron city that showed no significant association [13].
According to the anatomical site of AN, the neck was affected by 95.6% of cases followed by knuckles of fingers (37.4%) and hands (35.2%), and then axilla (14.2%). The neck is more liable to potentiated cofactors such as friction or perspiration, and mechanical factors, which have an important role on skin keratinocyte proliferation. A study was conducted in France, AN in the knuckles was a classic site and highly prevalent [15], on the same line with a study conducted by [16] Morthy and sudhakar in the medical outpatient department in a tertiary-care teaching hospital, nape of the neck was involved among all the patients with evidence of AN (100%). The distribution of AN in our study was localized (93.7%), the same higher percentage of localized AN was found in a study in Australia [17].
Regarding skin phenotype, the incidence of AN is the highest in those with skin types three and four, the lowest in whitest children. This was in agreement with a study conducted in Razi Hospital in Iran, where AN is much more common in people with darker skin, so that in whites, the prevalence is less than 1% [18]. This thesis revealed that the educational status of their mothers only had a significant impact on the prevalence of AN among children. Both the mother’s and father’s occupation have a great impact on role. This is explained by high-occupied parents, especially mothers who work outside would give their children heavy marketing of energy-dense foods and spent less time on meal preparation. This was in disagreement with a study conducted in Palestine [19]. According to associations, buffalo hump represents 17.3%, milia 16.2%, acne 11.0%, hirsutism 8.0%, skin tag 1.6%, stria 0.5%, and plantar hyperkeratosis 0.3% were reported in our study. This was in disagreement with a study conducted in India in which the associated cutaneous manifestations found in AN cases were skin tags (28%), followed by acne (11%), and hirsutism (5%) [19].
ConclusionAN remains a significant public health problem of which obesity-associated AN represents the majority of children having AN in our study. According to the results of the current study, we concluded that we need more effort to increase the awareness of the nature of AN, which is considered as dirty by majority of the community. School interventions and programs could be conducted to educate students and their parents about obesity and its risk factors, and initiate the standpoint of public policy, including availability of safe spaces for physical activity and healthy-nutrition choices in schools.
Acknowledgements
The authors would like to thank all support staff in outpatients’ clinics of Dermatology department.
Author contributions: substantial contributions to conception and design: Noha E. Mohamad. Acquisition of data: Noha E. Mohamad, Samar M.R., El-Tahlawy, Eman S. Ebrahim, and Naglaa A. Elsherbini. Drafting the article and revising it critically for important intellectual content: Noha E. Mohamad and Eman S. Ebrahim. Final approval of the version: Noha E. Mohamad. All the authors have read and approved the paper.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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