Methods for Locating the Pores of Epidermal Cysts

Dear Editor:

Epidermal cysts manifest as dermal or subcutaneous mobile nodules, and may have a clinically visible central punctum representing the plugging of the pilosebaceous unit from which cheesy debris may be expressed.

If treatment is desired, complete excision is the definitive treatment. The region of fusiform excision may be smaller than the area deformed by the cyst; however, the excision should include any poral opening attaching the cyst to the surface. If the entire cyst wall is not removed, the cyst can recur. Because the pore of an epidermal cyst is typically located at the center of the lesion, it is important for surgeons to be aware of the exact location of the central punctum of an epidermal cyst.

Tumescent local anesthesia was first described by Klein in 19871. He detailed the infiltration of large volumes of a diluted solution of lidocaine with epinephrine into fat before liposuction. Since then, the use of the tumescent technique has expanded to include other dermatological surgical procedures such as hair transplantation, laser surgery, and abdominoplasty2, 3. We describe the use of a simple pinch method and dermal tumescent anesthesia to locate the pores of epidermal cysts during excision.

The pinch method is a very easy technique to perform. The pore of an epidermal cyst can be made deeper and wider by pinching the skin with the thumb and the index finger. If the pore is already visible, the punctum can be made more prominent by using the pinching maneuver. If it is difficult to identify the pores on the basis of the gross appearance, the pores can be made visible by pinching several suspected lesions (Fig. 1).

Fig. 1
Pinch method. (A) On pinching the skin with the thumb and index finger, the pore of the cyst becomes deeper and wider. (B) An easy case: An already visible pore of a cyst (top panel) is made more prominent by using the pinching maneuver. (C) A challenging case: The pore is difficult to identify on the basis of gross appearance (top panel). However, the pore becomes visible after pinching (arrowhead).

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Another technique to locate the pores of epidermal cysts is the tumescent anesthesia technique. This technique is used for the delivery of local anesthesia, and it maximizes safety by using pharmacokinetic principles to achieve extensive regional anesthesia of the skin and subcutaneous tissue4. The subcutaneous infiltration of a large volume of very dilute lidocaine and epinephrine causes the targeted tissue to become swollen, or tumescent, and permits procedures to be performed without subjecting patients to the risks of local anesthesia and blood loss5. As the tumescent anesthesia technique causes the skin to swell, the pore of an epidermal cyst will become deeper and wider, and the tiny depression of the pore becomes easily notable. On rare occasions, keratinous material extrudes through the pore during tumescent anesthesia (Fig. 2).

Fig. 2
Tumescent anesthesia technique. (A) Tumescent anesthesia causes the skin to swell. Accordingly, the pore of the cyst becomes deeper and wider. (B) During tumescent anesthesia, the tiny depression of the pore becomes easily notable (arrowhead). (C) On rare occasions, keratinous material extrudes expressed through the pore during tumescent anesthesia (arrowhead). The position of the pore before injection is marked by an arrow.

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We use a commercially available solution of 2.0% lidocaine with epinephrine at 1 : 100,000 dilution. A 26-gauge needle on a 2-ml syringe is used to inject the anesthetic. Only the tip of the needle is inserted into the papillary dermis, at an approximately a 45° angle. The solution is injected slowly to allow diffusion of anesthesia within the dermis and to prevent increased intradermal tissue pressure. Although neither the pinch method nor the tumescent anesthesia technique is a completely new procedure, surgeons can easily apply these simple methods during the excision of epidermal cysts.