6Cheek
Abstract
The cheek is a common site of Mohs surgery and subsequent reconstruction. It is a large subunit with complex topography that borders many other facial subunits. Thus, many factors must be considered while operating in this area. This chapter addresses relevant anatomy such as the facial nerve and parotid gland and duct that one must take into account prior to performing surgery on the cheek. Illustrations are shown of the vascular, neural, and glandular anatomy and in addition the relaxed skin tension lines. A unique subunit principle of the cheek, with illustration, is presented including the considerations for these different subunits. An algorithm for approaching reconstruction of a cheek defect is laid out based on location and size of the defect. Reconstructions are discussed and shown with complimentary photographs especially of the more challenging repairs. This chapter ends with a discussion of possible complications that may occur subsequent to a surgery in this area and things to consider in minimizing complication risk.
Keywords: cheek anatomy, Mohs, skin cancer, cheek defects, flap, repair, cheek reconstruction
Capsule Summary and Pearls
•The cheek is a large subunit bordering many other complex facial subunits that must be taken into account when performing surgery in this area.
•Beware of the well-known danger zones where damage of branches of the facial nerve is of higher likelihood (Fig. 6.1).
•The relaxed skin tension lines (RSTLs) of the cheek as well as dynamic and static lines from the muscles of facial expression run parallel and often defects are sutured in this plane to minimize appearance of scarring (Fig. 6.3).
•The cheek can be divided up into eight subunits based on location with each having different skin quality and considerations given proximity to different neighboring facial subunits (Fig. 6.4).
•A reconstructive algorithm can be used as a guide when faced with a cheek defect (Fig. 6.5).
•There are minimal naturally occurring lines on the cheek; if equivocal repair options, consider the repair with the least number of lines (i.e., linear repair has one).
•Curvilinear repairs on the cheek are of great value given convexity and allowing one to minimize tissue redundancy and tension on the eyelid.
•Advancement flaps, including the V-Y advancement flap, are very useful on the cheek given large reservoir of mobile skin on lateral cheek and superior neck.
•Suspension sutures to the medial canthal tendon or periosteum of the nasion or orbital rim are of great value to minimize risk of ectropion.
•The bilobed transposition flap, as utilized on the nose, can be used for very large defects on the cheek with success when reconstructive options are limited.
•Eversion, while still utilized on the cheek, may take a longer time to resolve than other facial sites.
•Standing tissue cones at the inferior pole of a curvilinear repair may persist, while those falling superiorly in the eyelid will often relax.
6.1 Introduction
The cheek is a common area of treatment in Mohs micrographic surgery (MMS) and subsequent reconstruction. It is also one of the larger subunits and borders many other complex structures and subunits (ocular, auricular, oral, nasal, temporal, neck) and defects often may have significant overlap with other facial subunits. The first thing to consider in evaluating and treating a tumor with MMS, and then ultimately the reconstruction of the resulting defect, is the relevant anatomy of a particular area. The relevant anatomy of the cheek is discussed in the following section.
6.2 Relevant Anatomy
In discussing the anatomy of the cheek, we will start by addressing the anatomical structures deep to the surface of the skin. Then we will go on to discuss the superficial peripheral borders and boundaries of the cheek along with the aesthetic subunits of the area.
The superficial fascia, also known as the superficial muscular aponeurotic system (SMAS), of the cheek contains many important anatomic structures. These include the parotid gland and duct, muscles of facial expression as well as branches of the facial and trigeminal nerve, and the facial artery and vein. The parotid gland lies in the inferolateral portion of the cheek in the superficial fascia. The branches of the facial nerve and of course the parotid duct arise from the anterior border of the parotid gland. The parotid duct courses anteriorly from there lying atop the masseter muscle and can be found about 2 cm inferior to the zygomatic arch. The transverse facial artery and buccal branch of the facial nerve can often be found in close proximity to the parotid duct as well. As the parotid duct continues more anteriorly/medially, it eventually pierces the buccinator muscle of the cheek and drains into the oral cavity. The branches of the facial nerve (temporal, zygomatic, buccal, mandibular, and cervical) arise from within the parotid, and a diagram of these branches, the well-known danger zones,1 and parotid gland and duct anatomy is seen in Fig. 6.1.
Fig. 6.1 Please note the above anatomy of the cheek including the parotid duct and facial nerve. Specifically pay attention to the danger zones where the temporal and mandibular branches of the facial nerve lie more superficially and are at higher risk of damage in these areas. The mandibular branch of the facial nerve is found in the cheek and its course parallels the inferior margin of the mandible.
The facial artery crosses the mandible at the anterior border of the masseter muscle lying deep to the platysma in this location. As it progresses proximally at the angle of the mouth, it gives off the inferior labial and superior labial branches and once it reaches the lateral nose it becomes the angular artery. The infraorbital artery enters the cheek through the infraorbital foramen of the maxilla and anastomoses with branches of the facial artery listed earlier.2 The vascular anatomy of the cheek is shown in Fig. 6.2.
The relaxed skin tension lines (RSTLs) begin at the nasolabial fold (NLF) and run parallel to the NLF and eventually parallel to the inferior lateral canthal lines upon progressing more laterally. At the lateral cheek, they begin to no longer run parallel to aforementioned lines and run vertically parallel to the preauricular crease. The RSTLs are important to consider in reconstruction given reconstruction in these planes has the least amount of tension.3 Additionally, in particular for cheek reconstruction, the RSTL plane is also the same plane that all naturally occurring dynamic and static lines (rhytids) are formed over time from movements of the muscles of facial expression. Thus, reconstructions can be performed and can be best hidden if placed within already formed lines or lines that will form in the future. These RSTLs are shown in Fig. 6.3.
Fig. 6.3 The relaxed skin tension lines (RSTLs) are shown above. Specially pay attention to the parallel nature of these lines to the nasolabial fold as they progress laterally and how they change as they approach the auricular and ocular areas.
6.3 Aesthetic Subunits and Defects
The cheek’s peripheral borders are the infraorbital rim and zygomatic arch superiorly and the border of the mandible inferiorly. The medial border is the nasofacial junction, NLF, and labiomandibular crease medially and the preauricular crease laterally.4 For the purposes of this text, we will divide the cheek up into eight subunits all approximately 3 to 4 cm2 in size. These are the superomedial cheek, medial cheek, inferomedial cheek, superior central cheek, central cheek, inferior central cheek, superior lateral cheek, and inferior lateral cheek. These different subunits have different quality of skin with medial subunits being thicker and more sebaceous and superior and lateral subunits being more thin and nonsebaceous when approaching eyelid and preauricular skin. Different repairs are considered in each of these areas primarily based on size and location but also certainly considering differing skin qualities, proximity to other facial subunits and topography of each specific area. These different subunits are displayed in Fig. 6.4.
This figure nicely diagrams these different cheek subunits and the overlap and borders they have with other subunits of the face (ocular, auricular, oral, nasal, temporal, neck). This clearly is a very important consideration in reconstruction of the cheek given defects often are not contained to just one of the facial subunits. Each of the other (noncheek) facial subunits have their own considerations, which are addressed elsewhere in this text, that one must take into account when faced with a cheek defect that overlaps into, approximates, or closely approximates another facial subunit.
6.4 Reconstructive Options
The reconstruction options on the cheek are vast given the diverse areas of the cheek that border many unique structures such as the nose, mouth, eye, and ear. Additionally, the cheek has a large surface area among the facial subunits, thus allowing for larger tumors solely involving the cheek and sometimes necessitating very large repairs. The algorithm shown in Fig. 6.5 has been constructed as a basic guide when approaching a cheek defect. The variables addressed are size and location of the defects, which then guide one to some possible repairs to consider given those variables. Further discussion of different repairs and other considerations are included in the text in the sections to follow.
