A clinical evaluation of skin tags in relation to obesity, type 2 diabetis mellitus, age, and sex.

BACKGROUND: Skin tags (STs) have been investigated as a marker of type 2 diabetes mellitus (DM), yet the relation of STs to obesity is still a matter of controversy. AIM: The aim of the study is to explore the relation of number, size and color of STs to obesity, diabetes, sex and age in one study.
METHODS: The study included 245 nondiabetic (123 males and 122 females) and 276 diabetic (122 males and 154 females) subjects. We recorded age, sex, body mass index (BMI), relevant habits, STs color, size, and number in different anatomical sites.
RESULTS: The presence and the mean number of STs was more in obese than nonobese participants (P = 0.006 and P < 0.001, respectively) and was not affected by sex. However, the number increased significantly with age. The presence of mixed-color STs was related to obese (P < 0.001) participants. Multivariate logistic regression revealed that only BMI was significantly associated with the mixed-color STs (OR = 3.5, P < 0.001). The association of DM (OR = 1.7) with mixed-color STs was nonsignificant (P = 0.073). Neither age nor sex had any association with mixed-color STs. Within cases that developed mixed-color STs, the multivariate analysis showed that only BMI had a significant correlation to the number of STs (beta = 0.256, P = 0.034).
CONCLUSION: The study showed that not only the number but also the presence of mixed-color ST was related to obesity, but not to diabetes. The presence of mixed-color STs in nondiabetic subjects needs close inspection of BMI.

Introduction

Obesity and impaired glucose tolerance (IGT) are high risk factors for developing diabetes mellitus (DM). IGT is characterized by plasma glucose response to an oral glucose challenge that is above normal but not at the level defining DM. Individuals with IGT manifest abnormalities in both insulin action and early insulin secretion, similar to those seen in patients with type 2 DM.[1] Obesity and a high fat diet may contribute to the development of both insulin resistance and insulin secretory dysfunction in susceptible individuals.[1] Currently, there are no clear parameters to identify the patients with IGT or obesity who proceed on to DM.

Skin tags (STs), soft fibromas, fibroepithelial polyps, or acrochordons are all alternative terms to describe a common benign skin condition, which consists of a bit of skin projecting from the surrounding skin.[2] Histologically, STs is a polypoid lesion with overlying mildly acanthotic epidermis, a loose, edematous fibrovascular core exhibiting mild chronic inflammation and a nerveless dermis.[3] They often develop in areas of skin friction.[4] STs have been reported to be associated with many diseases including type 2 DM[5-7] and obesity.[89] STs have been investigated as a cutaneous marker for type 2 DM and obesity by measuring glucose curve, body mass index (BMI)[510] and insulin level.[1112]

Although the relation of STs to insulin resistance and type 2 DM was established in previous studies,[11] further studies are warranted in the area of obesity and STs.[13] Thus, to explore this area, the relation of the number, size and color of STs to obesity, diabetes, sex and age will be analyzed in one study.

Material and Methods

This study was conducted in a university hospital. The total number of participants was 521. The nondiabetic group included 245 participants from the outpatient clinic of dermatology [123 (50.2%) males and 122 (49.8%) females]. The diabetic group, including 276 participants (type II DM receiving oral hypoglycemic tablets), were from outpatient clinic of DM (122 (44.2%) males and 154 (55.8%) females.

History taking highlighted age, sex, marital status, family history of diabetes, and history of cardiac, hepatic, gastrointestinal or endocrinal disorders, other than DM. Individuals with an associated medical condition were excluded from the study (including pregnant women). Fasting blood glucose for the nondiabetic group was estimated to exclude occult diabetes. BMI was calculated for all cases according to the following equation:[14] BMI = [weight (kg)] / [height(m)]2. The internationally accepted range for BMI is as follows: underweight <18.5, normal 18.5–24.9, overweight 25.0–29.9, obesity 30.0–39.9 and extreme obesity >40.

Number, size, site and color of STs were examined and evaluated in all the participants [Table 1]. The following classification parameters were used (modified from Kahana et al.).[5] Number: Few (1–4), moderate (5–10) and many (>10). Size: Very early (visible not felt), small (projection of <0.5 cm), medium (0.5–1 cm) and large (>1 cm). Site: Eyelids (right–left), neck (right–left), axilla (right–left), trunk (right–left). Color: Flesh color, hyperpigmented or of a mixed color. Mixed-color STs means the presence of both colors, i.e., flesh and hyperpigmented STs in the same anatomical area as in the neck, or in the axillae [Figure 1].

Table 1

Number and percent of the studied population including males, females, nonobese, obese, nondiabetics, diabetics, STs prevalence and STs color

Figure 1

The mixed-color STs in neck

These parameters of STs were compared in the diabetics and obese versus the nondiabetics, nonobese. Data were statistically described in terms of range, mean ± standard deviation (±SD), frequencies (number of cases) and relative frequencies (percentages). Comparison of quantitative variables between the study groups was done using Student's t test for independent samples. For comparing categorical data, Chi square (χ2) test was performed. Exact test was used instead when the expected frequency was less than 5. Correlation between various variables was done using Pearson moment correlation equation. A probability value (P value) less than 0.05 was considered statistically significant. All statistical calculations were done using the computer programs “Microsoft Excel 2003” (Microsoft Corporation, NY, USA) and “SPSS” (Statistical Package for the Social Science; SPSS Inc., Chicago, IL, USA) version 15.

Results

In order to explore the controversy in literature concerning the relation of STs to obesity, the relation of the number, size and color of STs to obesity, diabetes, sex and age was analyzed. The basic characteristics studied are presented in Table 1.

Relation of skin tags to age and sex

The mean number of STs in the studied group was 5.36 ± 11.920, while the mean age of the studied group was 45.30 ± 12.540. In this study, the number of STs correlated significantly with age (P = 0.002). There were no significant differences in prevalence and mean number of STs between males and females groups (P = 0.555 and P = 0.358, respectively). Also, there was no significant difference in the prevalence of STs colors (flesh, dark and mixed) between males and females groups (P = 0.313).

Relation of skin tags to obesity

The prevalence of STs was detected more often among obese participants 199/310 (64.2%) compared to nonobese participants 110/211 (52.1%). This was statistically significant (P = 0.006). The mean number of STs was significantly higher among obese participants (7.11 ± 14.998) in comparison to the nonobese (2.92 ± 4.957, P < 0.001). The prevalence of mixed-color STs was significantly more among obese participants [81 (42.2%)] compared to nonobese [18 (17.6%], P < 0.001). On the other hand, the prevalence of flesh-color [58 (56.9%)] and hyperpigmented [26 (25.5%)] STs was higher in the nonobese group in comparison to the obese group [75 (39.1%)], and 36 (18.8%), respectively], (P < 0.001) [Table 2].

Table 2

Relation of the color of STs to obesity

Relation of skin tags to diabetes mellitus

The prevalence of STs was more often among the diabetic patients 167/276 (60.5%) in comparison to nondiabetic participants 142/245 (58.0%). However, this finding was not statistically significant (P = 0.555). The mean number of STs was higher among diabetics (6.28 ± 13.745) in comparison to nondiabetics (4.45 ± 10.016). This finding was also not statistically significant (P = 0.087). The prevalence of mixed-color STs was significantly higher among diabetics [70 (43.2%)] compared to nondiabetics [29 (22.0%)] (P < 0.001). On the other hand, the prevalence of flesh-color [68 (51.5%)] and hyperpigmented [35 (26.5%)] STs was higher in the nondiabetic group in comparison to diabetic group [65 (40.1%) and 27 (16.7%), respectively], (P < 0.001). The multivariate logistic regression for the factors associated with the occurrence of mixed-color STs is given in Table 3, while the multivariate regression analysis for the factors affecting the number of mixed-color STs is given in Table 4.

Table 3

Multivariate logistic regression for the factors associated with the occurrence of mixed-color STs (n = 294)

Table 4

Multivariate regression analysis for the factors affecting the number of mixed-color STs (n = 256)

Relation of skin tags size to sex, obesity and diabetes mellitus

Comparison of the mean number of STs of different sizes between males to females was nonsignificant. The mean number of medium size STs was significantly higher in diabetic participants than nondiabetics (P = 0.003), while the mean number of small size STs was significantly higher in obese subjects than nonobese (P < 0.001) subjects.

Relation of skin tags in different anatomical sites to sex, obesity and diabetes mellitus

Comparison of mean number of STs in different anatomical sites was nonsignificant between males and females and between diabetics and nondiabetics. Yet, it was statistically significant in obese to nonobese subjects in the right axilla (P = 0.010), in right side of the neck (P < 0.001), left side of the neck (P = 0.001) and in the trunk (P = 0.040).

Discussion

To our knowledge, this is the first report that points to particular characteristics of STs’ color among obese individuals where mixed-color STs prevail.

Relation of skin tags to age

In our study, the mean number of STs increased with age and reached a peak value, then declined (between 51 and 60 years in the diabetic and the nonobese groups and between 41 and 50 years in the nondiabetic group), except for the obese group in which it continued to rise with age. The decline of STs’ number was reported also by Thappa[7] in a study done on 35 subjects with STs. He reported that the risk of getting STs was found to increase with age and the risk of developing STs decreased after the fifth decade. In another report done by Banik and Lubach,[15] they inspected 750 subjects for STs incidence. They recorded that age of 50 years seems to be a turning point at which a stagnation of increase is observed.

Relation of skin tags to diabetes and obesity

In literature, there are two main parameters for predicting type 2 DM, IGT and obesity. The study of Motala et al.[16] represents a mirror image of these parameters. A 10-year study of oral glucose tolerance test was applied on South African Indians, known for their high prevalence of type 2 DM. The study showed that only 91/563 (16.2%) were diabetics. From the nondiabetic group, only 49 (9.5%) progressed into DM. They concluded that higher baseline blood glucose, BMI and obesity are considered as significant predictors of type 2 DM.

In our study, the increase of STs’ numbers was found to be related to obesity rather than DM. On one hand, this finding goes with the results of Puneet and Deepak[8] who reported an association between STs, IGT and obesity; it is also in accordance with the results of Garcia-Hidalgo et al.[9] who studied 156 obese patients and found that percentage of those with acrocordons increased with severity of obesity, and recently, the results corroborated the finding of Ramazan Sari et al.[11] who found that 38/113 (33.6%) of patients with STs were obese. On the other hand, our study contradicts with the observation of Rasi et al.[10] They reported that patients with more than 30 STs were particularly at an increased risk of DM. In our study, the occurrence of STs in the diabetic group was not significantly higher than those in the nondiabetic group (P = 0.555). Also, the mean number of STs among diabetics was not statistically higher than the nondiabetics (P = 0.087). On the other hand, the occurrence of STs in obese participants was significantly higher than nonobese participants (whether diabetic or not) (P = 0.006). Also, the mean number of STs in obese was significantly higher than the nonobese participants (P < 0.001). This contradicts the results of Kahana et al.[5] who showed that STs were not associated with increased incidence of obesity compared to the general population (as it was a single group study without control subjects gathered specifically for his study) and contradicts the results of Rasi et al.[10] and Ramazan Sari et al.[11] They found no correlation between the number of STs and BMI.

Now, do these results support any data at the molecular level? Yes, they support the results of Manal and Olfat.[17] They reported that the tissue expression of insulin-like growth factor (IGF-I) in STs of obese subjects was 2093.3 ng/g, while in STs of diabetic subjects it was 829.3 ng/g. Generally, hyperinsulinemia may induce both fibroblast and epidermal proliferation, which are the main components of STs, via activation of IGF-I receptors.[18]

Relation of skin tags’ color to diabetes and obesity

In the univariant comparisons, the prevalence of mixed-color STs was significantly more among obese participants than the nonobese (P < 0.001) and in the diabetics than the nondiabetics (P = 0.001). But in exploring the factors affecting the occurrence of mixed-color STs by multivariate logistic regression, only BMI was found to be significantly associated with the mixed-color STs (OR = 3.5, P = 0.001). DM also has an obvious association (OR = 1.7) but was nonsignificant (P = 0.073). Neither age nor sex had any obvious association. Within cases that developed mixed-color STs, the multivariate analysis showed that only BMI had a significant positive correlation (beta = 0.256, P = 0.034). Apart from the flesh-color STs, dark-color STs may be hypothesized by the interaction of mast cells[19] and the melanocytes[20] as in urticaria pigmentosa or postinflammatory pigmentation. Another explanation is through acanthosis and papillomatosis which are sufficient – without pigment producing cells – to make STs dark.[13]

Relation of skin tags in different anatomical sites to sex, diabetes mellitus and obesity

Comparison of mean the number of STs in different anatomical sites were only significant in obese to the nonobese subjects. This may be explained by more friction in obese subjects.[4] The mean number of STs was significantly higher in the right axilla (P = 0.010), in the right side of the neck (P < 0.001), in the left side of the neck (P = 0.001) and in the trunk (P = 0.040).

Conclusions

Although the relation of STs to insulin resistance and type 2 DM was established in previous studies, further studies are warranted in the area of obesity and STs. The results of this clinical study showed that not only the number but also the presence of mixed-color ST was related to obesity, but not to diabetes. The presence of mixed-color STs in nondiabetic subjects need close inspection of BMI.

Recommendations

A study recording the effect of weight reduction on color, number and size of STs is advised.