Dermatology Online Journal

New mechanical device for effective removal of skin tags in routine health care
Carina H Fredriksson, Michail Ilias, Chris D Anderson
Dermatology Online Journal 15 (2): 9

Linköping University Hospital, Linköping, Sweden. chris.anderson@lio.se

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Abstract

Skin tags (acrochordons) are exceedingly common benign skin lesions. A novel medical device in the form of a flat adhesive patch applies pressure to the base of a skin tag, leading to its removal within 3-6 days. The device was used in a clinical trial to treat and remove skin tags of the neck, upper torso, and axillae in volunteers. In this study, a total of 177 skin tags were treated in 32 individuals. One hundred seventy-two lesions fulfilled intention to treat (ITT) criteria. A majority of ITT lesions (90%) reached final assessment. Successful outcome was highest (90%) for lesions up to 1 mm in base. For lesions up to 2 mm, the rate of successful outcome was 76 percent. The desired outcome was seen in 65 percent of all ITT lesions. The cosmetic outcome after removal was excellent. Discomfort was assessed as minimal during all stages of the procedure. Analysis of data on blood flow in the skin tags during the treatment showed that the outcome was influenced by whether a decrease in blood flow was achieved immediately after application and at 2-3 days, but that the degree of occlusion was not critical. The results of this study illustrate that the device presents a new option for the management of unmet needs in the treatment of skin tags.

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Introduction

The occurrence of potentially life-threatening malignant neoplasia in the skin focuses attention on all departures from the skin's normal appearance. Since most parts of the skin are accessible for inspection, there is an opportunity for early detection, by the patient, of potentially dangerous neoplasms such as malignant melanoma, squamous cell cancer and a long list of other rare neoplasms. Great effort is spent in educating the population to seek medical advice early. The vast majority of skin lesions are, however, benign. Thus the majority of individuals seek advice for lesions for which there is no medical need for treatment. The patient may, however, desire removal of the lesion for cosmetic reasons.

Figure 1
Figure 1. Skin tags have variable appearance, size and histology, but follow some basic morphological types.

Common benign skin lesions include verruca, seborrhoic keratoses, fibromas, histiocytomas (dermatofibromas), nevi and skin tags. A skin tag is a small outgrowth of epidermal and dermal tissue, 1 to several mm in size, usually flesh-colored and pedunculated. Skin tags display a variety of shapes (Fig. 1) and are described by alternative names, of which acrochordon is the most accepted [1]. The common sites for skin tags are the neck, axillae, trunk and groin but they can occur all over the body. Larger lesions are often fibrosed nevi.

Skin tags have a reported incidence of 46 percent in the general population [2], although it seems likely that the "life-time prevalence" of these lesions may reach 100 percent. Detailed studies remain, however, to be done to improve the factual base in this issue. It is known that some medical conditions such as obesity, diabetes, insulin resistance, and atherosclerosis are associated with more frequent skin tags but the presence of skin tags is in itself of minimal diagnostic use [1, 3]. Skin tags can also be seen in pregnancy [4]. Little is known about the pathogenesis of skin tags but in some related benign conditions, effects on growth of fibroblasts in association with insulin resistance as well as focal changes in the genome have been implicated [5, 6].

The current medical treatment of skin tags involves clipping or shaving the lesion at the base, cryotherapy, or diathermy. Cryotherapy is perceived as inexpensive (it does not require anesthesia) but there are a number of drawbacks. Cryotherapy is not targeted, so healthy tissue is also destroyed, it is painful and there is a risk of blistering, scarring, and pigmentation changes [7]. Alternatively, patients can undertake "self-treatment" by traumatizing the most accessible lesions in different ways including the classic tying off with a sewing thread.

Patients are motivated to the removal of skin tags but the health care infrastructure is often less interested because skin tags are benign and the cost of a clinical intervention can be hard to justify, regardless of the psychological impact on the patient. Skin anomalies such as skin tags may strongly affect the patients' quality of life. Even slight changes in the skin may result in adjustments to social life, relationships, and even the ability to carry out daily tasks [8].

Figure 2
Figure 2. Schematic picture of a pedunculated skin tag showing the hyperplasia of the dermis with loosely arranged fibers and a well developed vascularisation.

Histologically, a skin tag shows localized hyperplasia of the dermis with loosely arranged collagen fibers and dilated capillaries and lymphatic vessels (Fig. 2), indicating that a skin tag is softer, more elastic, and about as vascularized as the surrounding skin. The epidermis can be slightly hyperplastic. The present paper trials are a new medical device in the form of a flat adhesive patch that exerts pressure on the base of a skin tag to cause strangulation.

Figure 3a	Figure 3b
Figures 3a & 3b. Skin tags have variable histology in regard to the stroma and the degree of cell density.

The cellular characteristics of the skin tag are important from the point of view of removal by pressure at the base. Figures 3a & 3b depict the histology of two different lesions. Figure 3a shows a floppy pedunculated skin tag. The connective tissue stroma is thin and loose with few cells.

Externally exerted pressure would result in little resistance from the tissue and the vasculature would easily collapse. These lesions tend to be smaller. However, the presence of nevus cells and a firm connective tissue network may protect the vasculature at the base from pressure (Fig. 3b). These lesions are often larger, broader in base and "dome shaped," and exert more resistance to compression of the base. A complete occlusion of the vasculature at the base could be expected to result in a necrosis of the skin tag. When occlusion of the base is incomplete, a degree of inflammation can be expected. The inflammatory response, by causing swelling, may enhance the occlusive effect.

The general aim of the present study was to investigate the use of a new medical device for the treatment of skin tags in a clinical situation. Specific aims included (1) to document the occurrence and degree of occlusion in blood flow by pressure at the base of the skin tag by the device; (2) to assess tolerability; (3) to document the chronology of tag removal, healing, and the practical/cosmetic outcome of the procedure; (4) to suggest criteria to identify patient groups where the device can be used under medical supervision or as self care.

Materials and Methods

The study is composed of a main clinical study of the use and outcome of the device and a mixed bench top and clinical study of the relationship between compression distance, pressure and blood flow.

Subjects

A question of relevance for dermatologists is whether a "skin tag" may be malignant or have other medical importance. In the present study, all subjects were assessed by a dermatologist. The inclusion criteria were: Patients with skin tags who were interested in their removal; informed consent; 30 years or older (younger persons possibly having a more active nevoid component).

Exclusion criteria were: Other skin lesion requiring medical treatment; past history of malignant melanoma or other condition motivating histopathological diagnosis of all treated lesions; pigmented base; younger than 30; pregnant women.

All participants in the study were under the supervision of the study doctor and nurse.

The study was performed at the Skin Physiology Laboratory of the Department of Dermatology, University Hospital, Linköping, Sweden and at the Department of Biomedical Engineering, Linköping University from November 15, 2006, to March 26, 2007. The study was approved by the Regional Ethical Board of Östergötland, Sweden.

The device

Figure 4	Figure 5
Figure 4. The Devices were used to produce pressure at the base. Two different designs, the "z"- device and "w"-device are shown. Figure 5. The device being applied. Pressure at the ends of the device opened the occluding slit. The device could then be maneuvered over the skin tags body to occlude the base. An adhesive layer on the back of the device attached it to the skin surface.

During the study, two different test-device designs with regard to the method of producing pressure were used: "z"- and "w"-shaped (Fig. 4). Devices were provided by TagAway Devices ApS, Denmark. Figure 5 shows how a test-device is applied to a skin tag in order to exert pressure at the base.

Blood flow measurements using laser Doppler

Two techniques were used to assess the effect of the device on blood flow.

Laser Doppler Perfusion Imaging (LDPI) is a non-invasive technique in which mapping with a laser light beam and measurement of the nature of the reflected light gives a two-dimensional image consisting of perfusion data of the study area [9]. A LDPI scanner by Lisca AB (PIM I, Lisca AB, Sweden) was used in this study. Software (LDPIwin version 2.3, Perimed AB, Sweden) was used in the management of the numerical aspects of the data collected in a computer to measure blood flow in the skin tag area, termed the region of interest (ROI), and the comparison to a reference region of normal skin in the same area. All images were 40 x 40 pixels in size. The size of the area was chosen so that the ROI comprised about 80 percent of the skin tag area.

Laser Doppler flowmetry (LDF) utilises the same technique as LDPI but involves placement of a fiber probe lightly on the skin tag. The system used (PeriFlux 4001 Master, Perimed AB, Sweden) is a sensitive technique and gives a reading from exactly the site measured but no image of the area [10]. When blood flow to the area is diminished, the signal is reduced. Software analysis of the signals was done in PeriSoft for Windows (version 2.5.5, Perimed AB, Sweden) before and after the application of the device and allowed quantification of the degree of blood flow occlusion during a period of 3 to 20 seconds during which no movement artefacts could be discerned.

Main clinical protocol

Once the above criteria were met, lesions up to 6 mm in base were included. The study was based on four visits. On Day 0, a visual inspection and selection of the study lesions took place. The size of the skin tags was determined and the form classified. LDPI and LDF were performed before and directly after application of a test-device in order to allow for comparison of the grade of occlusion achieved and the outcome.

On Day 2/3, the progress of the treatment was assessed by visual inspection and measurement of the blood flow with LDPI.

On Day 5/6, after visual inspection, the device was removed and the status of the treatment noted. The visit was completed by blood flow measurement with LDPI.

On Day 21-28, the final visit day, a final medical assessment was performed. The success of the treatment was graded by visual inspection.

For each subject, a Clinical Research File (CRF) was created. Each lesion treated was documented separately within the CRF. All data including skin tag number and morphology, the subject's demographical data, documentation of blood flow measurements and photographs were stored anonymized in a digital master file (DMF). All subjects gave their consent to participate in the study by signing a consent form after written and verbal information.

Clinical assessment of treatment outcome

The appearance of the lesion during treatment and at Day 21-28 follow up was documented according to the following possible outcomes. (i) Grading of appearance of the skin tag at day 5/6 (removal): 0 - skin-colored; 1 - swollen; 2 - dusky; 3 - dry/necrotic; 4 - came off with device; 5 - came off with device and bled; 6 - inflamed/bleeding. (ii) Grading of appearance at day 21-28 (outcome): 0 - skin-colored; 2 - dusky; 4 - came off; 7 - came off with some residual left. Successful outcome was considered for gradings "4" and "7" at Day 21-28.

Patient reactions and attitudes

An open dialogue was maintained with the subjects throughout the study. Discomfort or pain were noted on a visual analogue scale (VAS) graded from 0 (no discomfort) to 10 (highest possible discomfort). In order to acquire data on the subjects' attitude to the study itself and the treatment with test-devices especially, a questionnaire was sent to the participants, which they were asked to fill in anonymously.

Pressure Study

Figure 6	Figure 7a
Figure 6. The open slit produces the occlusive pressure to the base of the skin tag. For the pressure studies, the compression distance, i.e., x/2 varies depending on the base size of the skin tag. Figures 7a & 7b. Pressure producing Device (Fig. 7a). In Figure 7b the device is in use with the LDF fiber placed on the actual skin tag.

Figure 7b

To investigate the relationship between the pressure delivered by the device at the base of the skin tag and the blood perfusion through the skin tag, a study was performed in two steps: Firstly, the pressure delivered by the devices was determined on the bench top as a function of compression distance, i.e., the distance (gap) between the pressure applying surfaces of the device divided by a factor 2 (Fig. 6). Secondly, the compression distance was simulated in vivo by a pressure measuring device (Figs. 7a & 7b), so that the effect of different compression distances on skin tag perfusion could be measured by means of LDF.

Figure 8
Figure 8. Device for bench top measurement of force as a function of displacement. Figure 8b shows a close view of the test device.

In other words, the compression distance is directly translated to a specific pressure, depending on the actual skin tag measured. In the first step, a portable force indicator (PFI 50N, S.I. Instruments PTY, Ltd, USA) with a resolution of 0.001 kg was used in a bench top study to measure the pressure delivered in vitro by the test devices at different compression distances from 0.1 to 0.5 mm at 0.1 mm steps (Fig. 8). The increasing steps were determined with the help of a vernier calliper. The upper limit of the compression distance was set to 0.5 mm since no gaps wider than 1 mm were observed during skin tag treatment. The second step was performed by means of a tailor-made pressure gauge, specially designed to simulate the TagAway devices, thus delivering and measuring the pressure at the base of the skin tags at the same time. This system includes a pressure sensor (Flexiforce, A201-1 Model, Tekscan, Inc, USA), attached between two plastic surfaces. The readings from the sensor were A/D-converted and recorded using standard solutions provided by National Instruments (DAQCard 6024E and Labview 6.1, respectively). The gauge was calibrated against a precision scale (Mettler PE360, Mettler-Toledo Inc, Sweden) with a resolution of 0.001 grams. The LDF technique was used to evaluate the perfusion changes imposed by the gauge. Pressure was applied in a consecutive and stepwise increasing manner on each skin tag, ranging from 0 up to approximately 50 grams, in 10 grams steps. The initial measurements were done in vivo on individuals participating in the main study. This material was then extended by enrolling subjects exclusively in the pressure study. All individual skin tags (a total of 33) fulfilled the same inclusion and exclusion criteria set for the main study. All lesions were subsequently treated by means other than the device.

Results

The clinical material

Figure 9a	Figure 9b
Figure 9. Treatment and Outcome in three cases (a-c) at Days 0, 2/3, 5/6 and 21/28.

Figure 9c

The study encompassed treatment of 177 skin tags on 32 subjects, of whom 24 were women and 8 were men. Age ranged between 36 and 78 years with an average age of 61 years. One hundred sixty-six lesions (94%) reached the planned device removal Day 5/6 and 160 skin tags (90%) reached the final assessment between Days 21 and 28 as dictated by the protocol. Figure 9 (a-c) shows a number of lesions which had a positive outcome (grading 4 or 7 as seen in the method).

Analysis of excluded lesions

A total of 17 lesions left the study prematurely. In five cases, the test-device was removed after initial measurements on Day 0 since base pigmentation was observed, thus fulfilling an exclusion criterion. Of the 172 ITT lesions in the study, a total of 12 skin tags (7%) did not complete the protocol due to (1) patient not attending the follow up during the study (1 subject, 2 skin tags); (2) skin tag treated by other means due to swelling at Day 2/3 or 5/6 (2 and 5 cases, respectively); (3) loosening of the device (3 lesions). Swelling occurred mostly for larger lesions being more than 2 mm in base and more than 5 mm long. Test-Devices that loosened had been applied in the neck region.

The overall success of the treatment of skin tags (treatment outcome grading 4 and 7, see methods) for the 172 ITT was 65 percent. A detailed analysis of factors affecting successful outcome follows.

Influence of size, shape, and localization of the skin tag on the treatment outcome

The size of the skin tag showed a marked influence on the outcome of the treatment.

Generally, successful treatment was highest for smaller tags. For skin tags with base diameter <1 mm, the success rate was 90 percent. For skin tags with a base diameter <2 mm, the success rate was 76 percent. These two groups constituted 83 percent of all skin tags treated in the study and were the subject of further analysis presented below.

Figure 10a	Figure 10b
Figures 10a - 10c. Overview of the successful treatment of skin tags with the device depending on the morphology of the tag (Fig. 10a), the age of the patient (Fig. 10b), and the duration of the occlusion (Fig. 10c).

Figure 10c

Concerning skin tag morphology, the best results were achieved for lamellar and filiform tags (86% and 79% successful outcome, respectively). The success rate for other morphologies within this size class was slightly lower (64-76%, Fig. 10a). Most of the treated lesions were located in the patients' axillae and neck regions. A better outcome for skin tags localized to the axillae was observed compared to the neck (85% vs. 71%). The success rate decreases slightly with increasing age of the patient (Fig. 10b).

Influence of treatment duration on the treatment outcome

The protocol aimed at a device application time of 5 to 6 days. For practical or subject-steered reasons this application time varied in some cases. A statistically relevant correlation between successful outcome and the duration of treatment could not be found (Fig. 10c).

Pressure study

Figure 11
Figure 11. The normalized blood flow values for different pressure intervals induced as shown in Fig 7. Normalization was performed against the unaffected skin tag (before occlusion).

In the pressure study, measurements were performed on 33 lesions in 13 subjects. Most skin tags were located in the axillae and the lower neck region. For the analysis, the perfusion data was normalised against the perfusion of the unaffected skin tag (prior to occlusion) and was arranged in groups with applied pressures between 0-10 g, 10-20 g, 20-30 g, 30-40 g, 40-50 g (Fig. 11). A decrease in blood flow was observed with stepped increase in applied pressures. A force of up to 50 g will reduce the perfusion by 80 percent in average. The biological zero, BZ, (the perfusion value recorded at total occlusion) is thought to emanate from Brownian motion of red blood cells and spontaneous movements in the microvasculature [11], and is thus greater than zero. The contribution of BZ to the perfusion value of rest flow is affected by a number of different parameters and may vary greatly [11, 12]. Therefore, whether 40, 60, or 80 percent reduction in blood perfusion corresponds to BZ cannot be concluded. A comparison to absolute perfusion values obtained while occluding arterial flow at the base of a test subject's finger suggested that almost 80 percent of the skin tags were totally occluded at some point during the stepped pressure maneuver. In all but two cases this appeared in the skin tags at a pressure below 35 g.

Thirty-four individual devices of two different designs (Fig. 4) were tested in vitro with a force indicator. W-shaped devices (n=24) delivered an average force of 75 g (deviation 75±34 g), exceeding the requirement for total occlusion. Z-shaped devices (n=8) were weaker (18±10 g), indicating that partial occlusion of the blood flow may occur in the skin tag. For both designs, an occlusion distance of 0.2 mm was chosen, similar to the gap between the compression surfaces of the device when applied to a skin tag.

Analysis of the blood flow alteration during treatment

Figure 12a	Figure 12b
Figure 12a. LDPI screen image of a skin tag examination. The right picture shows the "photo" of the skin tag (seen as a dark area) and a surrounding area of normal skin. The left picture is the image of blood flow. ROIs can be chosen in the software. The table in the screen image shows the difference between skin tag perfusion (ROI 1) and normal perfusion (ROI 2). Figure 12b shows the blood flow in the skin tag after occlusion by the device (ROI 1).The table in the screen shows the mean to be lower than in the ROIs shown in Figure 12a.

Figure 13	Figure 14
Figure 13. LDF signals from a skin tag befor (a) and after application of the device (b). PU- perfusion units, CMBC- concentration of moving red blood cells, vel- average velocity of red blood cells ; PU ~ CMBC* vel. Complete occlusion does not lead to a signal of zero. In this example the perfusion was decreased by 77 percent. Figure 14. Outcome chart for a blood flow reduction to any degree after device application (Day 0 and at Day 2/3). Outcomes were deemed "successful" at Day 21/28 if the lesion came off.

Laser Doppler perfusion imaging (LDPI) and laser Doppler flowmetry (LDF) measurements were performed before and after device application and at Days 2/3. The relation between blood flow reduction in the region of interest (ROI) corresponding to the skin tag and outcome was analyzed (Fig. 14). A decrease was observed in 96.9 percent of lesions after device application. At Days 2/3, 87.6 percent showed some degree of occlusion, leading to successful outcome in 80.5 percent of these lesions. For skin tags, where no decrease in flow could be measured, only 37.5 percent of applications had a successful outcome.

A further analysis was performed to assess the impact of 20, 40, and 60 percent reduction in blood flow on the outcome. No significant increase in the rate of successful outcome was observed for higher flow reduction. Remarkably, the success rate for lesions not fulfilling the success criteria increased to 52 percent, 69 percent, and 71 percent, respectively. Thus, a measured decrease to any degree in blood flow after device application was important for a successful outcome rather than the degree of occlusion achieved.

Subject tolerability (discomfort grading)

Figure 15
Figure 15. Subject discomfort during application procedure, between Day 0 and Day 2/3, between Day 2/3 and Day 5/6 and until the final visit.

Patients were asked about their degree of discomfort at all visits. Throughout the study subjects rated their discomfort as minimal. The application procedure was generally experienced as "pricking" to a small degree. During the days following the application of the device some itching occurred, in several cases accompanied by slight scratching. The majority of subjects (90%) graded the discomfort during treatment between 0 and 1 on a scale of 0-10. No discomfort scores higher than 2 were recorded (Fig. 15).

A post-study questionnaire including a renewed enquiry about discomfort was also performed. Twenty-three of 30 contacted subjects responded. Seventy percent of the responders reported no discomfort throughout the treatment. The remainder reported some itching or irritation.

Discussion

In this study, a new device was tested to treat skin tags in a setting that resembles the everyday clinical environment. The success rate in lesions with a base diameter <1 mm was very high (90%). Lesions <2 mm in base diameter had a success rate of 76. It can be envisaged that design development, lesion selection, and clinical use may improve this outcome further. At an individual lesion level, the physical criteria set for successful outcome were removal with little or no scarring and with minimal discomfort. The outcome of the study is therefore extremely satisfactory on these criteria.

The impairment of blood flow in the skin tag is central to the treatment. To our knowledge, no previous studies are available on the expected blood flow levels in skin tags or appropriate target levels for reduction to hinder blood flow and promote necrosis of the skin tag. The device can deliver adequate pressure to achieve blood flow impairment levels that were either total or near to total without mechanically crushing or cutting the tissue. The pressure study documented the occurrence and degree of blood flow decrease in skin tags but was not used to guide treatment. Measurements were performed immediately after device application and at Days 2/3, i.e., at only two points in time during the 5-day application period. Since a proportion of lesions where no flow reduction was detected had a successful outcome, it must be inferred that an adequate blood flow reduction was achieved at some time point during the 5-day period for these lesions to achieve necrosis. Thus, occlusion of blood flow remains the sole patho-etiological hypothesized mechanism for the effectiveness of the treatment concept and achieving it remains the primary aim.

Another important feature is tolerability. In the present protocol, the skin around the tag was protected by a thin adhesive film onto which the device was applied. In most situations this gave good tolerability. Repetitive movement gave some irritation especially in the creases of the neck and the frontal aspect of the axillae (because of arm movement). If irritation in a lesion became pronounced in the present study, a decision was made to interrupt the study and remove the skin tag surgically. This decision was conservative and may have been unnecessary. As clinical experience grows, more lesions may be left to run their full course because a degree of inflammation promotes vessel occlusion. Improvements in device design and material can be expected to increase tolerability.

The present study was conducted in a clinical environment similar to an ambulatory clinic. Treatment could be left in the hands of paramedical personnel and is more convenient than surgical treatment. Application of the device by the patients themselves requires further study but in the questionnaire many patients felt that they could learn to apply devices. Practical and educational issues need further attention especially in the development of correctly formatted information to avoid use of the technique on potentially dangerous lesions.

In conclusion, we demonstrate the effectiveness of a new device for skin tag removal. The treatment is safe and well-tolerated with virtually no discomfort. The cosmetic results of the use of the device are excellent.

Disclaimer: The authors have no commercial interest in the device tested. The practical performance of the study was supported by the company developing proof-of-concept for the tested device, Tag Away A/s, Denmark

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