Читать книгу Veterinary Surgical Oncology - Группа авторов - Страница 143

Many types of reconstructive techniques are available to close defects created by wide removal of skin tumors, and the detailed description of these techniques is beyond the scope of this chapter. Large defects on the head, neck, and body can often be closed using a variety of local and axial pattern skin flaps (Kirpensteijn and Ter Haar 2013). Despite the relatively good outcome of axial pattern skin flaps in the long term in cats and dogs, short term complication rate was high (90%) and a second surgery for revision of the reconstruction was performed in 30% of the cases in a recent report (Field et al. 2015). Surgeons and patient‐owners, therefore, need to be prepared for the possibility of a prolonged aftercare after surgery for large tumors. Skin reconstruction on the distal limbs is more challenging because local and axial pattern flaps are usually not applicable. Options are either aiming for complete excision with narrow margins by excision just outside the tumor pseudocapsule, including underlying muscle fascia, in relatively well‐defined low‐intermediate grade STS, sparing part of the skin if it is not attached to the tumor. Depending on specific tumor type, margin status, and tumor grade, additional radiation therapy may prevent local recurrence (see specific section on radiation therapy). Another option is aiming for a wide excision and thus creating a large skin defect. There are several options to close large distal extremity wounds, including vascularized skin pouch flap, tubed vascularized skin flaps, free vascularized skin flaps with microvascular anastomosis (Fowler et al. 1998), autologous skin transplant (with or without negative pressure wound therapy augmentation) (Stanley et al. 2013; Miller et al. 2016), or healing by second intention (Prpich et al. 2014). Leaving a wound open can often be preferred over an incomplete tumor excision. Healing by second intention has a relatively good outcome and prognosis, however, wound closure is slow and possible complications include a relatively fragile new skin after epithelization and the risk of developing wound contracture, especially in locations with high degree of motion such as the carpus. In one study evaluating second intention healing after STS removal over an extremity, the average time it took for wounds to heal was approximately two months and over 90% of wounds healed completely by second intention alone. Complications occurred in 23% of wounds during healing and 26% of wounds had complications long‐term (Prpich et al. 2014).

In some extremity locations, axial pattern flaps can be used (Henney and Pavletic 1988), such as the superficial brachial axial pattern flap and the reverse saphenous conduit flap (Elliot 2014; Cavalcanti et al. 2018) for the thoracic and pelvic limb, respectively. Use of the relatively lengthy thoracodorsal axial pattern flap for forelimb wounds was met with a relatively high complication rate of an average of 21% distant flap necrosis in 7/10 dogs and the need for surgical intervention in 6/10 dogs (Aper and Smeak 2003). A phalangeal fillet technique provides a sturdy closure of distal metacarpal/metatarsal wounds by sacrificing a digit (Figure 4.7) (Olsen et al. 1997; Demetriou et al. 2007; Cantatore et al. 2013).

Figure 4.7 Excision of STS at distal medial aspect of the metatarsus using a phalangeal fillet flap of digit II in a Heidewachtel. (a) Tumor and 1 cm excision margins drawn on the skin. (b) En‐bloc excision including metacarpal II and digit II and metacarpal III, metacarpophalangeal joint and proximal part of phalanx I of digit II, preserving the main blood supply of digit III. (c) Removal of the bones and nail of digit III (“fillet”), preserving soft tissues and blood supply. (d) Raising and rotating the phalangeal fillet flap into the defect. Note that the digital pad is preserved. This technique is also useful for footpad reconstruction. (e, f) Result after one week.

Although elliptical excisions are commonly used for skin tumor removal, several human studies claim to have better results with round excisions. Furthermore, the shape of the tissue to be excised is dictated by the tumor margins, which commonly results in more or less round wounds. In practice, only the lesion and the required margin of surrounding tissue are excised without attempting to design an elliptical skin incision. The resulting wound is closed by opposing the wound edges along the lines of least skin tension, starting in the center of the wound. Such round excisions result in 14–21% shorter sutured wound length and the wound direction differed from the predicted ellipse in 45% of cases (Hudson‐Peacock and Lawrence 1995). When using this technique, dog‐ears will obviously appear. In general, however, round excision with subsequent dog‐ear removal results in better‐oriented wounds than those achieved by elliptical excision, minimize tissue excision, decrease wound widening, and may still decrease the final sutured wound length (Lee et al. 2011). Dog‐ear reconstructions are relatively simple and can be performed directly after closure or at a later time (Borges 1982) by removal of the excess skin fold and thus extending the wound length. Techniques to reduce dog‐ear folds without removal of skin include suture techniques to anchor the dog‐ear to deeper tissues such as the dog‐ear tacking suture technique (Kantor 2015) and the three‐bite suture technique (Jaber et al. 2015). In the latter technique, a three‐bite suture is placed that sequentially pierces the deep fascial plane and each margin of the dog‐ear, thus flattening the dog‐ear by anchoring the over‐projecting skin to the deep plane. This is a fast, easy, and versatile method of immediate dog‐ear correction without extending the scar while maintaining a full and complete local skin blood supply (Jaber et al. 2015).

Another rarely discussed reconstructive technique is the cuticular purse string technique. In a retrospective study by Cohen et al. (2007), the authors reviewed 98 human patients after cuticular purse‐string suture placement. These sutures will achieve partial surgical wound closure and the postoperative wound area decreased by 6–90%, with a mean of 60% following purse‐string partial closure. The circumferential placement of the cuticular purse‐string suture makes it possible to recruit skin from the entire diameter without needing to undermine the wound edges. Generally, the purse string suture is removed three or four weeks after closure to allow the partially closed wound to completely heal by second intention. According to the authors of this study, this closure technique provides uniform tension to the wound, enhances hemostasis at the tissue edge, and significantly decreases the size of the defect. The technique has been described in people after surgical removal of skin tumors (Cohen et al. 2007) and is reported to be particularly suitable in older human patients because of their skin laxity (Raposia et al. 2014).

Pavletic (2000) described the use of skin stretchers 72–96 hours before excision of large tumors. Skin stretching is an easy way to mobilize skin and is reported to be successful in most cases. Two other techniques for stretching the skin after creating the surgical wound have been studied: staples as anchor points along the edge of each surgical wound margin and a hypodermic needle “skewered” through the skin parallel to each surgical wound margin (needle transpiercing the skin along the length of the margin, going in and out of the skin). Sutures are then placed between the staples or the needles on either side of the wound and tightened over a bandage material covering the open wound (Tsioli 2015).