Chapter 23: Conchal Bowl and External Auditory Canal

INTRODUCTION

The conchal bowl is an extremely common location for skin cancer. If the defect is small, it is an ideal location to heal with second intent. For larger tumours, skin grafts are the most common closure. Pull-through flaps can be used for defects which are missing cartilage in the conchal bowl.^1,2

Often, conchal bowl tumours extend into the external auditory canal (EAC). This creates the problem of preserving canal patency. Second intention healing will often lead to contracture of the wound and narrowing of the canal. Skin grafts are typically chosen for closure of these defects. Full-thickness grafts have less contracture than split-thickness grafts; however, they produce more oedema and can thicken and possibly narrow the canal.

Wound care is extremely important in these cases. During the extirpation of the tumour, a cotton ball or petrolatum-impregnated gauze can be placed in the EAC to prevent blood collection down the canal where it will clot and impair hearing (and may damage the tympanic membrane). Prior to closing the defect, the canal should be flushed with sterile saline. After the closure is performed, the canal can be packed with petrolatum-impregnated gauze again, which will maintain the canal patency. It also acts like a bolster to the grafts. It should be changed 5 days postoperatively and then every 2 days for the following week.

SECOND INTENTION

Advantages

• No extra surgery or suturing required

• Can provide excellent cosmetic results with scarring confined to the defect area

• Will decrease in size by contracting approximately 30% as it heals

Disadvantages

• Wound care is necessary for approximately 6 weeks

• Not as good for defects with a lot of exposed cartilage

• Graft colour and contour may differ from the surrounding skin

• Contraction can decrease the patency of the EAC

Technique

1. After the wound has been cleansed and haemostasis achieved, assess the wound for any areas of missing perichondrium. The avascular cartilage will not promote healing and, therefore, several perforations through the cartilage are necessary to create portals through to the underside of the cartilage which will aid in granulation. A 1 to 2 mm punch is placed about every 5 mm.

2. Apply antibiotic ointment or petrolatum to the wound. Do not leave any form of haemostatic bandage (gel foam or calcium alginates) on the wound as these tend to dry out the area. This makes subsequent dressings hard to remove and also delays healing due to dehydration of the perichondrium.

3. Apply a non-stick dressing with a light pressure dressing on top for the first 24 to 48 ...