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Table of Contents
Year : 2018  |  Volume : 22  |  Issue : 1  |  Page : 28-29

Eccentric hyperbola: A new modified cutaneous scar re-excision on convex surfaces

1 Department of Plastic and Reconstructive Surgery, The Royal London Hospital, Barts Health NHS Trust, London, UK
2 Barts and The London School of Medicine and Dentistry, London, UK

Date of Web Publication31-Jan-2018

Correspondence Address:
Dr. Georgios Pafitanis
4 Newark Street, Whitechapel, E21AT, London
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jdds.jdds_2_18

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“Re-excision of scar” is a common procedure following diagnostic or therapeutic excision of skin cancer cutaneous lesions. With the conventional techniques, skin tension on convex surfaces results in deformity and elongated scars. We present a modified technique for cutaneous scar re-excision that designed along the skin tension lines to enable improved outcomes; the “eccentric hyperbola”. We demonstrate the effectiveness and outcomes of this modification using geometrical regression analysis. This modified technique proves to demonstrate benefits over conventional elliptical excisions on convex surfaces resulting in reduction final scar length and to our experience, enables improved cosmetic outcomes.

Keywords: Wide local excision, cutaneous surgery, scar re-excision

How to cite this article:
Pafitanis G, Hadliandreou M, Gilleard O, Moir G. Eccentric hyperbola: A new modified cutaneous scar re-excision on convex surfaces. J Dermatol Dermatol Surg 2018;22:28-9

How to cite this URL:
Pafitanis G, Hadliandreou M, Gilleard O, Moir G. Eccentric hyperbola: A new modified cutaneous scar re-excision on convex surfaces. J Dermatol Dermatol Surg [serial online] 2018 [cited 2022 Aug 16];22:28-9. Available from: https://www.jddsjournal.org/text.asp?2018/22/1/28/224391

  Introduction Top

“Re-excision of scar” is considered standard practice following diagnostic excisional biopsy or therapeutic excision of skin cancer with infiltrated or incompletely excised margins.[1] Elliptical or fusiform incision is a simple, versatile, and the most common excision technique.[2],[3] Two hyperbolic lines in 3:1 or 4:1 length-to-width ratio and <30°C, aim uniform primary closure without “dog-ear” formation.[2] Other techniques include tangent-to-circle or rhombic and parallelogram, that connect two triangles across a circular sector on their bases, aiming even, tapered, and symmetric final scar.[2] Surgical excision is influenced by the skin surface anatomy. In regions with skin convexity and lack of depth in cutaneous tissue, surgical design aiding primary closure is challenged by defect biomechanics. We present a modified technique for cutaneous scar re-excision; the “eccentric hyperbola, demonstrating the step-by-step design, along with geometrical regression analysis enabling improved scar length on convex skin surfaces.

  Surgical Technique Top

Re-excision of scar in line with the dominant axis on a convex skin surface is challenging to achieve, without wound distortions. In addition, skin tension line stresses the re-excision scar by retraction forces, especially when orientated vertical to the wound edges. A 45°C rotation to the dominant axis of excision forms the modified eccentric hyperbola. This technique utilizes tissue from the wound edges of the rotated re-excision dominant axis while recruiting skin from surface convexity and incorporating subcutaneous tissue planes to improve final primary closure outcomes [Figure 1]a.
Figure 1: (a) Skin excisional biopsy scar with markings demonstrating: Elliptical re-excision (red), eccentric hyperbola (blue), anatomical surface curvature (gray). (b) Eccentric Hyperbola re-excision markings. (c) Re-excision eccentric hyperbola skin incisions completed with exposure of the superficial subcutaneous fat

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  Results Top


To design an eccentric hyperbola, the dominant axis of the excision scar is marked out. The orientation of the skin tension lines and the vectors of surface convexity in relation with the re-excision dominant axis are marked. This technique allows the dominant axis of re-excision to be re-oriented (45°) such that the final scar lies in the optimal direction [Figure 1]a.[2] Two vertical markings at the scar edges (in guidance of margins) and two hyperbolic lines (in accordance with the vectors of surface convexity) along the dominant axis of re-excision are marked [Figure 1]b. The reverse hemiellipsoid re-excision tissue is removed. [Figure 1]c The closure is achieved vertical to the dominant axis re-excision. The final scar is shorter than the conventional technique and without surface contour distortions [Figure 1]a.

Geometrical regression analysis

A primary lesion is excised using a fusiform design with dominant axis equal to the sum of the lesion diameter (x) plus two times the excision margin (y); (x + 2 y), multiplied by the factor 3 or 4 in 1:3 or 1:4 width-to-length ratio, respectively. (3) This results to a final excision scar length (l) = 3 (x + 2y) or 4 (x + 2y) [Figure 2].
Figure 2: Schematic representation of eccentric hyperbola versus conventional elliptical re-excision markings on scar, demonstrating: diameter of primary lesion (x), excisional biopsy margin (y), excisional biopsy scar length (l), scar length with elliptical re-excision (L)

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Conventional fusiform re-excision of scar leads to re-excision scar length (L) with re-excision margins (Y) of three or four times (l + 2Y). This results to a final re-excision scar length range from L = 9x + 18y + 6Y to 16x + 32y + 8Y.

When the dominant axis of re-excision is rotated by 45°, as designed in eccentric hyperbola technique, the final scar length is shortened. This improves the length of the final scar by 30%.

  Discussion Top

Tension-free primary closure in convex cutaneous re-excision should follow the skin tension lines (Langer's lines) and the surface convexity.[4] Clinical and experimental studies suggest that skin incisions along these tension skin lines achieve better outcomes.[4],[5] In 1834, Dupuytren et al. described that circular skin excisions tend to gape in healthy skin. A study investigating wound contraction rates and wound morphology in various anatomical areas and direction of skin tension lines in a porcine model found that following circular excision and primary closure of a skin lesion, the biomechanics created by the skin tension lines influence scar formation along those lines of tension.[6]

These principles applied in this modification of cutaneous re-excision technique, utilize the underlying tissue biomechanics to adjust the hemiellipsoid excision to the surface anatomical convexity. This allows a 30% scar length reduction and unnecessary healthy tissue excision.

  Conclusion Top

Eccentric hyperbola proved a versatile add-on in cutaneous surgical armamentarium, and despite positive regression analysis results, more clinical studies are required to define potential improved clinical outcomes. A prospective randomized study comparing various anatomical convex regions is necessary before any definitive conclusion can be drawn.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Etzkorn JR, Cherpelis BS, Glass LF. Mohs surgery for melanoma: Rationale, advances and possibilities. Expert Rev Anticancer Ther 2011;11:1041-52.  Back to cited text no. 1
Goldberg LH, Alam M. Elliptical excisions: Variations and the eccentric parallelogram. Arch Dermatol 2004;140:176-80.  Back to cited text no. 2
Kraft J, Murray CA. The fusiform skin excision: One recipe for success. J Cutan Med Surg 2011;15:245-9.  Back to cited text no. 3
Meyer M, McGrouther DA. A study relating wound tension to scar morphology in the pre-sternal scar using Langers technique. Br J Plast Surg 1991;44:291-4.  Back to cited text no. 4
Langer K. On the anatomy and physiology of the skin II. Skin tension. Br J Plast Surg 1978;31:93-106.  Back to cited text no. 5
Kwak M, Son D, Kim J, Han K. Static langer's line and wound contraction rates according to anatomical regions in a porcine model. Wound Repair Regen 2014;22:678-82.  Back to cited text no. 6


  [Figure 1], [Figure 2]


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