There are several methods for removal of epidermoid cysts after infiltration of local anaesthetic over and around the cyst. They are the most common cutaneous cysts, which have a cheesy keratin material (not sebum). They can occur anywhere but most commonly on the face, scalp and trunk. These include the following methods.1
Make an incision into the cyst to bisect it, squeeze the contents out with a gauze swab and then avulse the lining of the cyst with a pair of artery forceps or remove with a small curette.
Use a 5 mm punch biopsy to punch a hole into the apex of the cyst. Squeeze vigorously to express the contents. Look for the cyst wall, grasp it with forceps and carefully enucleate it. A suture is not necessary.
Incision over cyst and blunt dissection
Make a careful skin incision over the cyst, taking care not to puncture its wall. Free the skin carefully from the cyst by blunt dissection. When it is free from adherent subcutaneous tissue, digital pressure will cause the cyst to ‘pop out’.
Incise a small ellipse of skin to include the central punctum over the cyst (Fig. 3.3a). Apply forceps to this skin to provide traction for dissection of the cyst from the adherent dermis and subcutaneous tissue. Ideally, forceps should be applied at either end. The objective is to avoid rupture of the cyst. Insert curved scissors (e.g. McIndoe’s scissors) and free the cyst by gently opening and closing the blades (Fig. 3.3b). Bleeding is not usually a problem. When the cyst is removed, obliterate the space with subcutaneous absorbable sutures. The skin is sutured with a vertical mattress suture to avoid a tendency to inversion of the skin edges into the slack wound. Send the cyst for histopathology.
Standard dissection of sebaceous cyst
On the first visit, inject LA into the overlying skin. Insert a heated electrocautery needle in the cyst and cauterise the contents for several seconds (Fig. 3.4).
Electrocautery to sebaceous cyst
On the second visit, 7 to 10 days later, inject LA, then make a small incision in the cyst and express the contents.
Treatment of infected cysts
Incise the cyst to drain purulent material. When the inflammation has resolved completely, the cyst should be excised as outlined above.
This method simply unroofs the cyst and allows healing by dressings over an open area. It should be avoided on the face or other areas where a puckered scar is unacceptable. It is very useful for an infected cyst.
Infiltrate the skin over the cyst with local anaesthetic.
Unroof the cyst by removing a disc of skin with scalpel or scissors. This disc should be slightly smaller than the diameter of the cyst (Fig. 3.5).
Evacuate the contents of the cyst and pack with paraffin gauze.
Apply pressure if bleeding is a problem.
Apply non-adherent dressings daily.
A simple deroofing method: (a) cross-sectional view; (b) surface view