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Surgical Flaps in Mohs Micrographic Surgery

Goddard, Lindsey; Ivey, Lauren; Seeburger, Jack

Journal of the Dermatology Nurses' Association: March/April 2019 - Volume 11 - Issue 2 - p 75–78
doi: 10.1097/JDN.0000000000000455
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ABSTRACT Skin cancer can be broadly categorized into melanoma and nonmelanoma skin cancer (NMSC). Squamous cell carcinoma and basal cell carcinoma are the most common subtypes of NMSC. When a patient presents with a skin finding suspect for NMSC, a confirming skin biopsy is performed. On the basis of the biopsy results, patient factors, and clinical characteristics of the cancer, an appropriate form of treatment is selected. Mohs micrographic surgery (or Mohs) is a tissue-sparing surgical approach, utilizing frozen section margin control. Once removal of the NMSC has been assured by Mohs surgery, the resultant skin defect is evaluated for repair. The choice of repair should maintain or restore function and aesthetic form while minimizing skin tension. Using a skin flap may be the best choice of repair to achieve these goals. Here, we describe both rotation and advancement flaps. Rotation flaps are constructed using an arciform incision adjacent to the original wound. Advancement flaps describe the movement of skin and tissue directly forward to close the wound, employing no rotational movement. There are three main subtypes of advancement flaps: unidirectional, bidirectional, and island pedicle or V-to-Y flaps.

Lindsey Goddard, MD, Department of Dermatology, Loma Linda University, Loma Linda, CA.

Lauren Ivey, MS, School of Medicine, Loma Linda University, Loma Linda, CA.

Jack Seeburger, MD, Department of Dermatology, Veteren Affairs Hospital, Loma Linda, CA.

The authors declare no conflict of interest.

Correspondence concerning this article should be addressed to Lindsey Goddard, MD, Department of Dermatology, Loma Linda University, 11370 Anderson Street, Suite 2600, Loma Linda, CA 92354. E-mail: lgoddard@llu.edu

Skin cancer can be broadly categorized into melanoma and nonmelanoma skin cancer (NMSC). Squamous cell carcinoma and basal cell carcinoma are the most common subtypes of NMSC, with basal cell carcinoma accounting for over 80% of this group (Hoorens et al., 2016). Melanoma contributes to only 1% of skin cancer cases but compromises the vast majority of skin cancer deaths. NMSC is the most common type of cancer found in humans with an estimated incidence of four million new cases diagnosed yearly (Rogers et al., 2010). Two important risk factors for developing NMSC are patient skin type and cumulative ultraviolet light exposure.

Typically, when a patient presents with a skin finding suspect for NMSC, a confirming skin biopsy is performed. On the basis of the biopsy results, patient factors, and clinical characteristics of the cancer, an appropriate form of treatment is selected. NMSC may be treated with one or more different modalities including surgical excision, topical chemotherapy, electrodessication and curettage, radiotherapy, Mohs micrographic surgery (Mohs or MMS), and systemic chemotherapy. Mohs or MMS, conceived by Dr. Frederic E. Mohs, is a tissue-sparing surgical approach, utilizing frozen section margin control, and offers the highest 5-year cure rate for NMSC (Lam & Vidimos, 2018; Moehrle & Läuchli, 2016). Common indications for Mohs surgery are aggressive histological subtypes, recurrent cancers, tumors in “mask” areas of the face, and neural or vascular invasion (Lam & Vidimos, 2018). Patients with a previous history of high-risk tumors or who are immunocompromised will also likely benefit from MMS.

Once removal of the NMSC has been assured by Mohs surgery, the resultant skin defect is evaluated for repair. The choice of repair should maintain or restore function and aesthetic form while minimizing skin tension. Using a skin flap may be the best choice of repair to achieve these goals. A skin flap is a three-sided composite of skin tissue layers that is transferred from one site (donor site) to another (recipient site) and carries with it its own blood supply. Among the surgeon’s reconstructive options, skin flaps can be categorized as described by their primary movement into flaps that slide and flaps that lift. Flaps that slide include advancement and rotation flaps, whereas flaps that lift include transposition and interpolation flaps. This article will review indications for, and examples of, rotation and advancement flaps.

Rotation flaps are constructed by creating an arciform incision adjacent to the original wound, which has been modified to a triangular shape with its most acute angle directed at the base of the arc (Figure 1). Rotation flaps are most suitable for areas with limited skin elasticity or availability, such as the scalp, and are frequently used in conjunction with other surgical flaps.

FIGURE 1

FIGURE 1

Advancement flaps describe the direct forward movement of skin and tissue to close the wound, employing no rotational movement. There are three main subtypes of advancement flaps: unidirectional, bidirectional, and island pedicle or V-to-Y flaps.

When constructing an advancement flap, a surgeon will create one or more linear incisions at the margin of the wound. The shape and direction of movement determine the subtype of the advancement flap. As with rotational flaps, the original wound may be expanded to create a triangular shape and facilitate closure. Rotational and advancement flaps often additionally employ Burow’s triangles, sections of removed skin outside the lesion created to excise cutaneous deformities that result when a large area of tissue is advanced (Baker, 2015).

Traditionally, a unilateral advancement flap creates two linear incisions extending in one direction from the original lesion using Burrow’s triangles at the base of the incision. A more frequently utilized version of the unidirectional advancement flap is the O–L flap or “L-plasty” (Figure 2). This flap utilizes skin laxity on one side of the defect and advances skin from this area into the wound.

FIGURE 2

FIGURE 2

Bilateral advancement flaps can be thought of as unilateral advancement occurring across a mirrored plane: two flaps advancing toward the wound in opposite directions with Burow’s triangles implemented at the base. A commonly used bilateral advancement flap is the O–T or “T-plasty” (Figure 3). This is similar to the O–L but utilizes tissue from either side of the wound, creating bidirectional movement into the wound with the final suture line resembling the letter T.

FIGURE 3

FIGURE 3

An island advancement flap is a subtype of unipedicle advancement flap in which an “island” or a segment of skin is positioned as to be evenly surrounded by the wound. The island pedicle is an island of skin, with all dermal margins severed, which has an intact subcutaneous pedicle that provides its blood supply (Figure 4). This design allows for larger flaps with good viability (Lee, Elner, Douglas, & Elner, 2011). Defects at the medial check near the alar base, as well as the medial canthal region, are good candidates for repair via island pedicle (Baker, 2015).

FIGURE 4

FIGURE 4

Postoperative wound care for MMS beings with the initial application of petroleum-based or antibiotic ointment to the sutures followed by a nonstick dressing. A bolster of dry gauze and hypoallergenic paper tape can be used to secure. Patients with good compliance may be instructed to clean the wound site with saline and reapply a new dressing daily. An alternate approach is to leave the wound undisturbed until the bandage can be reassessed at follow-up 5–7 days after surgery for suture removal and wound check (Cook, Goldman, & Holmes, 2015). With this method, adhesive strip tapes are applied over the sutured wound before being covered with a pressure dressing secured with mesh or cloth tape. With both methods, sutures should be removed in a timely manner, and the edges of the wound should be supported thereafter with adhesive tape strips. Pain from MMS is usually minimal and can be effectively controlled with acetaminophen (Lam & Vidimos, 2018). Patients should be encouraged to cease smoking and other tobacco products from 1 week before surgery to 2 weeks after to minimize the development of tissue necrosis (Cook, 2003).

In summary, advancement skin flaps provide excellent options for repair of MMS defects. See Table 1 for a general summary of utilization of rotational and advancement flaps.

TABLE 1

TABLE 1

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REFERENCES

Baker S. R. (2015). 24—Reconstruction of facial defects. In Cummings otolaryngology (6th ed., pp. 351–370). Philadelphia, PA: Elsevier.
Cook J. L. (2003). A prospective evaluation of the incidence of complications associated with Mohs micrographic surgery. Archives of Dermatology, 139(2), 143. https://doi.org/10.1001/archderm.139.2.143
Cook J. L., Goldman G. D., Holmes T. E. (2015). 17—Random pattern cutaneous flaps. In Surgery of the skin (3rd ed., pp. 252–285). Philadelphia, PA: Elsevier.
Hoorens I., Batteauw A., Van Maele G., Lapiere K., Boone B., Ongenae K. (2016). Mohs micrographic surgery for basal cell carcinoma: evaluation of the indication criteria and predictive factors for extensive subclinical spread. British Journal of Dermatology, 174(4), 847–852. https://doi.org/10.1111/bjd.14308
Lam C., Vidimos A. T. (2018). 150—Mohs micrographic surgery. In Dermatology (4th ed., pp. 2542–2555). Philadelphia, PA: Elsevier.
Lee B. J., Elner S. G., Douglas R. S., Elner V. M. (2011). Island pedicle and horizontal advancement cheek flaps for medial canthal reconstruction. Ophthalmic Plastic & Reconstructive Surgery, 27(5), 376–379. https://doi.org/10.1097/IOP.0b013e318222f106
Moehrle M., Läuchli S. (2016). Indications for micrographic surgery. British Journal of Dermatology, 174(4), 719–720. https://doi.org/10.1111/bjd.14505
Rogers H. W., Weinstock M. A., Harris A. R., Hinckley M. R., Feldman S. R., Fleischer A. B., Coldiron B. M. (2010). Incidence estimate of nonmelanoma skin cancer in the United States, 2006. Archives of Dermatology, 146(3), 5.
Keywords:

Dermatologic Surgery; Mohs Micrographic Surgery; Surgical Flaps; NMSC; Skin Cancer

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