Measurement of Epidermis, Dermis, and Total Skin

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Original Article

Measurement of Epidermis, Dermis, and Total Skin Thicknesses from Six Different Body Regions with a new Ethical Histometric Technique Pembe Oltulu, Bilsev Ince1, Naile Kokbudak2, Sidika Findik, Fahriye Kilinc Departments of Pathology and Plastic and Reconstructive and Aesthetic Surgery, Meram Faculty of Medicine, Necmettin Erbakan University, 2 Department of Pathology, Numune State Hospital, Konya, Turkey 1

Abstract Introduction: Although it is important to know the normal values of dermis, epidermis, or total skin thicknesses (ST) for some drugs and vaccine research, skin-related clinical investigations, and skin transfer operations used in plastic surgery, it would not be ethical to take new biopsies from healthy volunteers to measure their ST. This study aims to describe a new ethical histometric technique for the measurement of skin layers and to determine the mean ST of some major body regions in the people living in our region. Materials and Methods: A total of 180 skin samples from six major body regions of 90 males and 90 females were enrolled in the study. The measurements were performed histometrically from appropriate skin samples obtained from the pathology archive. The samples were classified according to the six different parts of the body (scalp, abdomen, back, dorsum of foot, dorsum of hand, and the breast). Results: The mean epidermal thickness ranged from 76.9 ± 26.2 to 267.4 ± 120.6 µm. The thickest epidermis was found in the dorsum of foot in women (267.4 ± 120.6 µm) while the thinnest was found in the breast in women (76.9 ± 26.2 µm). The mean dermal thickness ranged from 2115 ± 946.4 to 5888 ± 2422.3 µm. The thickest dermis was found in the breast in men (5888 ± 2422.3 µm), while the thinnest dermis was found in the dorsum of hand in women (2115 ± 946.4 µm). Conclusions: Human ST varies according to ethnic origin. It was determined that the dermis and epidermis of Anatolian people are thicker than that of the previously reported other ethnic groups. The skin pathology archive can be used to create maps of the body’s skin structure. Keywords: Dermis, epidermis, histometric, skin thickness

IntroductIon Skin, which is composed of the epidermis and the dermis, is the outermost tissue of the human body. The epidermis consists of the following four layers (from deep to superficial): basal layer, spinous layer, granular cell layer, and stratum corneum, whereas the dermis involves cells, connective tissue, and ground substance and contains blood and lymphatic vessels, nerves, glands, and hair follicles. The dermis is divided into two layers as the papillary dermis and the reticular dermis. There is a variable amount of subcutaneous fatty tissue beneath the skin.[1] Several studies have reported that human epidermis, dermis, and total skin thicknesses (ST) vary according to different body region, gender, age, and ethnic origin. [2-10] A few histopathological studies investigating differences in the thicknesses of the skin layers from different sites of human Access this article online Quick Response Code: Website: http://www.turkjplastsurg.org

DOI: 10.4103/tjps.tjps_2_17

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body based on ethnicity have been reported in the literature. These studies show data from American, Asian, and Caucasian people.[2,8,11] To the best of our knowledge, with the exception of one previous study[12] on the epidermis of the human breast, no other histopathological studies on the thicknesses of the skin layers of human breast have been reported in the literature, and no study has been conducted on the ST of Anatolian people. Although it is important to know the normal values of dermis, epidermis, or total ST for some drug and vaccine research, skin-related clinical investigations, and skin transfer operations Address for correspondence: Dr. Pembe Oltulu, Department of Pathology, Meram Faculty of Medicine, Necmettin Erbakan University, Konya, Turkey. E-mail: [email protected]

This is an open access journal, and articles are distributed under the terms of the Creative Commons Attribution‑NonCommercial‑ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non‑commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms. For reprints contact: [email protected]

How to cite this article: Oltulu P, Ince B, Kokbudak N, Findik S, Kilinc F. Measurement of epidermis, dermis, and total skin thicknesses from six different body regions with a new ethical histometric technique. Turk J Plast Surg 2018;26:56-61.

© 2018 Turkish Journal of Plastic Surgery | Published by Wolters Kluwer - Medknow

[Downloaded free from http://www.turkjplastsurg.org on Friday, April 13, 2018, IP: 10.232.74.27] Oltulu, et al.: Histometric analysis of the skin layers

used in plastic surgery, it would not be ethical to take new biopsies from healthy volunteers to measure their ST. This study aims to describe a new and ethical histometric technique for the measurement of skin layers. This study also aims to determine the measurement of epidermis, dermis, and total ST of certain major body regions in some people living in our region.

MaterIals and Methods A total of 180 skin samples from six major body regions of 90 males and 90 females were enrolled in this retrospective archive study. We focused on people aged between 30 and 40 years in order to minimize the effect of age factor on ST. People who had a body mass index ≥25 were excluded from the study.

Figure 1: Histopathological images of female breast dermis (left) and epidermis (right) (H&E, ×2, ×40)

Thirty skin samples (15 each from males and females) from each body region were evaluated. The study was approved by the local Ethics Committee. Hematoxylin and eosin-stained skin preparations of these regions were obtained from the pathology archives. All the samples were examined under a light microscope, and the skin samples that did not have at least 9–10 mm of healthy skin tissue adjacent to the surgical margins were excluded. All the measurements were performed on this 9–10 mm of healthy skin area between the lesion and the surgical margin and classified according to the six different parts of the body (scalp, abdomen, back, dorsum of foot, dorsum of hand, and the breast) and according to gender. One or two microphotographs (with 2X objective) were taken from each skin specimen using a digital camera mounted on an Olympus Bx51 microscope (Olympus Co., Shinjuku-ku, Tokyo, Japan). Thickness of the epidermis and dermis were calculate as micrometers (μm) digitally using Pixera software, image analyzing system (Compix Inc.). The epidermis was measured three or four times from the free margin of skin to the dermal papillae and epidermal rete ridge. The dermis was measured three or four times from the epidermal ridge and dermal papillae to the irregular dermal–fat junction [Figures 1-4].

Figure 2: Histopathological images of male back dermis (left) and epidermis (right) (H&E, ×2, ×40)

Figure 3: Histopathological images of dermis (left) and epidermis (right) of male dorsum of hand (H&E, ×2, ×10)

The mean and median, with standard deviation (SD), Q1 and Q2 values of epidermis and dermis, and total ST were calculated statistically using Microsoft Excel® (Microsoft Corporation, Redmond, Washington). The mean (µm) ± SD values were reported for gender and each body region.

results Different results were obtained for the female and male samples in the different body regions, as shown in Figures 1-4. The results of females and males are as follows.

Figure 4: Histopathological images of skin of male breast (left) and female dorsum of foot (right) (H&E, ×2, ×4)

The mean age of 90 females was 34 years (range, 29–40 years). Epidermal thickness ranged from 76.9 ± 26.2 to 267.4 ± 120.6 µm. Of the six body regions, the thickest epidermis was found in

the dorsum of foot (267.4 ± 120.6 µm), while the thinnest in the breast (76.9 ± 26.2 µm). Dermal thickness ranged from 2115 ± 946.4 to 4717.1 ± 1902.5 µm. The thickest dermis

Turkish Journal of Plastic Surgery ¦ Volume 26 ¦ Issue 2 ¦ April-June 2018

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was found in the breast (4717.1 ± 1902.5 µm), while the thinnest in the dorsum of hand (2115 ± 946.4 µm). Total ST ranged from 2310.2 ± 953.8 to 4794 ± 1905.1 µm. Of the six body regions, the thickest skin was found in the breast (4794 ± 1905.1 µm), while the thinnest in the dorsum of hand (2310.2 ± 953.8 µm) [Table 1]. The mean age of 90 males was 37 years (range, 31–40 years). Epidermal thickness ranged from 112.4 ± 22.9 to 244.8 ± 92.9 µm. Of the six body regions, the thickest epidermis was found in the dorsum of hand (244.8 ± 92.9 µm), while the thinnest in the scalp (112.4 ± 22.9 µm). Dermal thickness ranged from 2363.3 ± 960 to 5888 ± 2422.3 µm. The thickest dermis was found in the breast (5888 ± 2422.3 µm), while the thinnest in the dorsum of foot (2363.3 ± 960 µm). Total ST ranged from 2284 ± 1407 to 6052.4 ± 2435.4 µm. Of the six body regions, the thickest skin was found in the breast (6052.4 ± 2435.4 µm), while the thinnest in the dorsum of hand (2284 ± 1407 µm) [Table 2].

dIscussIon Epidermis, dermis, and total ST vary in different healthy human body regions according to body site, gender, age, and ethnic origin.[2,5-9] It is important to know the normal values of dermis, epidermis, or total ST for some drug and vaccine research, skin-related clinical investigations, and skin transfer operations used in plastic surgery.[2,3,5,8,9,13,14] Although it was claimed that increased dermal thickness is a risk factor for wide scar formation,[13] the normal thickness of different human body regions is not yet fully known. For this purpose, many studies on human ST from many different regions have been published in the literature. In these studies, a wide variety of measurement methods have been used; epidermis and dermis thicknesses of different body regions have been measured, and the relationships with age, gender, and ethnicity have been evaluated. These studies have found some similarities and some differences.[2-18] Split-thickness skin grafts used in plastic surgery can be taken many times from the same region. The greatest limitation of this graft removal is dermis thickness. As some dermis is taken during each graft operation, a thick dermis is an important source in a recurrent split-thickness graft donor area. Repeat split-thickness skin grafts are very important, especially in patients with extensive burns. Knowing the thickness of the epidermis is important to prevent the development of postoperative hyperpigmentation after skin regeneration techniques such as peeling dermabrasion.[13] It has been known that the thinnest ST is in the eyelids,[19] and hypertrophic scars very rarely occur on the scalp, eyelids, and anterior lower leg.[20] In contrast, the sternum, shoulders, upper arms, earlobes, and cheeks are the most susceptible regions to keloid and hypertrophic scar formation. It was claimed that this difference is associated with increased dermis thickness.[13] Our results support this claim because although thickness of the eyelid skin was not measured, we found that scalp is one 58

of the thin body regions. Knowing the approximate thickness of the dermis before surgery might help to mitigate the risk of hypertrophic scar. Measuring the thickness of skin layers has some limitations. One limitation is that there are many measurement methods and there is no standardization. Invasive and noninvasive methods are both used in the measurements of epidermis, dermis, and epidermis + dermis which include computed tomography (CT), magnetic resonance imaging (MRI), or ultrasonographic (USG) evaluations; tissue biopsies for histometric evaluation or cadaveric studies; and new techniques such as confocal microscopy.[2-4,9,14-18] MRI and CT are expensive techniques for measuring of ST, and they cannot provide detailed information as much as microscopic examinations. Cone beam CT, although low rates have been reported, also has radiation effects. While there are no radiation effects with USG, a definite objective result cannot be obtained with this method. In addition, the reported ST varies significantly among studies, in which imaging procedures are used to determine ST.[9,15] Confocal microscopy instrumentation methods can provide accurate measurements. However, it is still in the development phase.[17] In some studies, breast ST in women was measured on film-screen mammograms.[18] Direct radiography is not a suitable method for measuring whole-body skin regions, as it produces radiation effects and epidermis and dermis thicknesses cannot be measured separately. Tissue collection for histometric evaluation of ST is an invasive method, and it is not ethical to take a punch biopsy from healthy human volunteers for experimental purposes only. In the literature, there are only two studies measuring ST with punch biopsy.[2,5] It is not ethical to perform a punch biopsy from healthy individuals to measure ST. That is why we used skin biopsies of patients who were previously operated for skin lesions, which we obtained from the pathology archive of our institute. Our technique for measuring ST is suitable for all regions of the body where pathological skin sampling is possible and also ethical. To the best of our knowledge, there are no studies defining a measurement technique like ours. Another technique used to determine ST is cadaver studies. Investigators cannot provide enough male and female cadavers for adequate statistical results or cannot obtain permission from relatives of the deceased person to take a biopsy from autopsies. However, histometric studies remain the gold standard for studies involving the measurement of ST, as they provide more objective information than the other methods.[2,7,9,21] Thus, studies using histometric measurement methods and involving most of the body regions are very rare due to these negative aspects. In the present study, we measured epidermis, dermis, and total ST of six different regions of the body surface in adult Anatolian male and female patients using the traditional histometric method. However, we performed these measurements without taking new biopsies from healthy volunteers, autopsies, or cadavers to measure ST, due to international ethical rules. All the measurements were made retrospectively from the skin biopsy materials



Table 1: Female epidermis, dermis and total skin thickness acording to six body regions Regions (n: 90)

Epidermis (Ep)(μm)

Breast (n: 15) Scalp (n: 15) Abdomen (n: 15) Back (n: 15) Dorsum of hand (n: 15) Dorsum of foot (n: 15)

Dermis (Dm )(μm)

Total skin thickness (Ep + Dm) (μm)

Mean

SD

Median

Q1

Mean

SD

Median

Q1

Mean

SD

Median

Q1

76.9 111.4 127.2 140.2 195.3 267.4

26.2 28.1 38.1 36.6 79.2 120.6

64 108 125 132.5 181 238

55.7 93 107 122.5 145 205.7

4717.1 2238 4550 3264.8 2115 3184.7

1902.5 773.5 2147.7 929.7 946.4 1273.6

4523 1984 5295 3169 1864 3563

2837.5 1834.5 2697 2589 1548 1972.5

4794 2351.5 4679.5 3575 2310.2 3488.6

1905.1 774.5 2166.3 1141.3 953.8 1387.1

4626.5 2108 5426 3363 2170 3816

2891.7 1939.5 2790.7 26689.5 1743 2181

Table 2: Male epidermis, dermis and total skin thickness acording to six body regions Regions (n: 90)

Epidermis (Ep)(μm)

Breast (n: 15) Scalp (n: 15) Abdomen (n: 15) Back (n: 15) Dorsum of hand (n: 15) Dorsum of foot (n: 15)

Dermis (Dm )(μm)

Total skin thickness (Ep + Dm) (μm)

Mean

SD

Median

Q1

Mean

SD

Median

Q1

Mean

SD

Median

Q1

164.3 112.4 163.3 116 244.8 206.4

67.2 22.9 44.5 27.1 92.9 106.3

163.5 107.5 154 106 232.5 198

110.5 131.5 134.3 97.5 200.8 144

5888 31323.8 5497.7 5717.8 2538.5 2363.3

2422.3 1822.5 1722.2 1971 1373.9 960

5690 2579 5203 5640 2263 1965

4629.5 2356 4166 4538.5 1785 1724

6052.4 3245.2 5661 5834 2284 2583

2435.4 1816 1733.2 1958.3 1407 946

5891.5 2654 5417 5750 2529 2229

4808.3 2456 4340.7 4678 2037.5 1969.5

Table 3: Epidermis and Dermis thickness according to ethnic origin Epidermis (μm)

Dermis (μm)

Caucasian

Korean

Anatolian

Caucasian

Korean

Anatolian

Southwood*

Lee**

Current study (n: 180)

Southwood*

Lee**

Current study (n: 180)

(-) (-) 1248 1941 932 1001

5302,6 (n: 30, F+M) 2685,4 (n: 30, F+M) 5023,8 (n: 30, F+M) 4492,8 (n: 30, F+M) 2326,7 (n: 30, F+M) 2774 (n: 30, F+M)

Breast (-) (-) (-) 120,6(n: 30, F+M) Scalp (-) (-) (-) 111,9 (n: 30, F+M) Abdomen 41 79 1640 145,2 (n: 30, F+M) Back 66 76 1805 128,1 (n: 30, F+M) Hand back (-) 189 (-) 220 (n: 30, F+M) Foot back (-) 163 (-) 236 (n: 30, F+M) Caucasian values taken from *Southwood et al.[8] and **Korean values taken from Lee et al.[2]

obtained from the pathology archive of our institute. The skin slides to be evaluated for measurement were obtained from the slides’ archive and examined under a light microscope. The skin biopsies that had at least 9–10 mm of healthy skin tissue adjacent to the surgical margins and small-diameter tumoral lesions that did not change the normal structure of the skin in male and female patients who underwent surgery for a skin lesion were included in this study. The measurements were performed from this healthy skin areas. When performing calculations of the epidermis and dermis thicknesses, the most important points to pay attention to were irregular lower limits of the dermis and rete ridges of the epidermis, as these irregularities of the epidermis and dermis could be a potential problem for the standardization of measurements. To minimize this problem, three or four measurements were made of the thinnest and thickest segments of epidermis and dermis, and then the obtained values were averaged and recorded for each case, as shown in Figures 1-4. In a cadaveric study evaluating ST in human face, full-thickness 4 mm punch biopsy samples were obtained from 39 surgically

relevant anatomic locations of the face from 10 human cadaveric heads. However, in that study, only the face ST was determined, other body regions were not studied and the mean age of the ten cadavers was also 81.6.[9] In our study, the number of samples was 30 for each anatomical region and the ages ranged between 30 and 40 years. Since the skin gets thinner with age, this age range was preferred and the results were standardized. In the literature, one of the most comprehensive studies measuring ST is the study of Koreans with an average of 8.6 samples per region. However, in that study, only three samples were taken from some regions and the number of male and female samples also varied according to regions. In our study, the number of female and male samples was equal and two times more samples per anatomical region were included in the study compared to the study by Koreans. When compared to these two studies, the most important advantage of our study was the evaluation of previous preparations in the pathology archive without a need for additional biopsies. From this perspective, our study defines a new, easy, and a


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different ethical technique for measuring ST. Further studies can measure the epidermis and dermis thicknesses of many more anatomical regions with this technique. In the present study, we specifically examined samples from 30- to 40-year-old adults to minimize the effects of the age factor. We found that ST varies between regions of the body surface. Mean breast, back, and abdominal ST were higher in both males and females than that of the other regions. The dermis of these three regions was also thicker than those of the other regions. According to our results, scar can be more common in these regions.[13] However, the two regions with the thickest epidermis in both females and males were the back of the foot and the back of the hand. The third region with thickest epidermis was the breast in females and the back in males [Tables 1 and 2]. Mean breast ST was 6052.4 ± 2435.4 µm in males and 4794 ± 1905.1 µm in females. The breast skin had the thickest dermis in males and females (5888 ± 2422.3 µm and 4717.1 ± 1902.5 µm, respectively), but the thinnest epidermis was observed in females (76.9 ± 26.2 µm). There are differences between the measurements of our study and those of the other studies found in the literature.[1,8] We found that the dermis and epidermis of Anatolian people are much thicker than those of other ethnic groups. Epidermis thickness of back has been measured as 66 µm in Caucasian people and 76 µm in Korean people. We found this thickness as 128.1 µm. The epidermis thickness of abdomen has been found as 41 and 79 µm in Caucasian people and Korean people, respectively, and we found this value as 145.2 µm in our study. The dermis thickness of back has been measured as 1805 and 1941 µm in Caucasian people and Korean people, respectively. We found the dermis thickness of back as 4492.8 µm in our study. The dermis thickness of abdomen has been found as 1640 and 1248 µm in Caucasian people and Korean people, respectively, and we found this value as 5023.8 µm. The results for other regions are shown in Table 3. A major limitation of the present study is that it has a low number of body regions. Only six different body regions had been included in the study because of the need for large samples of healthy tissue. It was very difficult to collect a lot of samples with a wide surgical margin (at least 9–10 mm) from a wide variety of human body regions in this ethical histometric method. However, our main goal at first was to create maps of the body’s skin structure by comparing six different regions. In future studies, ST of all body surfaces of both the Anatolian people and other ethnic groups can be measured using this ethical histometric method, in centers with wider case populations. All the skin samples in the present study belonged to the people living in Anatolia. Although the case number of groups is low, these preliminary results can provide pioneering data for determining the ST of Anatolian people. It is important to know the normal values of human ST, especially according to ethnic origin. Many ethnic groups can be analyzed using our technique. Using both histometric and ethical methods, the current study measured the thickness of skin from different 60

body regions of a small population of the Anatolian people. Although studies on ST related to American, Asian, and Caucasian people are available, the present study is the first to conduct histometric measurements of the Anatolian people.

conclusIons Human ST varies according to ethnic origin. In this study, it was determined that the dermis and epidermis of Anatolian people are thicker than that of other ethnic groups which have been reported in the literature. The existing pathological skin samples obtained from pathology archives can be used to create maps of the body’s skin structure. In future studies, this map can be further improved using this method with biopsy materials from other body regions.

Financial support and sponsorship Nil.

Conflicts of interest There are no conflicts of interest.

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