Epidermal Cysts: Minimal Excisional Removal

E. J. Mayeaux, Jr, MD, DABFP, FAAFP
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Introduction

Epidermal (sebaceous) cysts are a common complaint in primary care. The cysts arise from the pilosebaceous glands associated with skin adnexal structures. Within the cyst is a white to yellow, cream cheese-like substance commonly (but incorrectly) referred to as sebum. Cysts vary in size from a few millimeters to 5 cm in diameter and have a doughy to firm consistency. Some cysts emit a rancid odor, which is due to the lipid content of the cyst and sometimes decomposition of cyst contents by bacteria. The cysts usually are mobile within the skin, unless they have previously ruptured and scarred the surrounding tissue. 
The contents of the cyst induce a tremendous inflammation if they leak. Most “infected epidermal cysts” are sterile, and the inflammatory response is due to the sterile inflammatory reaction. Many individuals prefer to have cysts removed before they have the opportunity to leak and become inflamed. Inflamed cysts are more difficult to remove surgically and do not excise well with the minimum excision technique. 
Simple incision and drainage is a poor treatment choice, because recurrence with this method is very common. Most providers remove epidermal cysts in toto via incision and dissection. The minimal excision technique was developed to completely remove the cyst with a minimal skin scar. It the cyst wall is not completely removed, future attempts should be attempted using the standard technique. 
Many lesions can be confused with epidermal cysts. If a solid tumor is discovered at the time of the procedure, a biopsy should be obtained. Incisional biopsy can be performed for very large lesions, and excisional biopsy for the smaller lesions. Pilar tumors of the scalp are often confused with epidermoid cysts and may require wide excision because they can erode into the skull. 

Equipment

  • Basic office surgery instruments are used for the standard excision technique (Appendix G). However, the minimal sebaceous cyst removal technique can be performed with a no. 11 scalpel blade, two or three small mosquito hemostats, and sterile gauze.

  • A suggested anesthesia tray that can be used for this procedure is listed in Appendix F.

  • Skin preparation recommendations appear in Appendix E.

Indications

  • Lesions with the clinical findings or appearance of sebaceous cysts, preferably those that have not previously been inflamed or scarred

  • Fluctuant or compressible lesions in common areas for sebaceous cysts (e.g., face, neck, scalp, behind the ears, trunk, scrotum)

Contraindications (Relative)

  • Local cellulitis

  • Severe bleeding disorders

  • Failed previous minimum excision attempt on the specific lesion. A cyst that has previously ruptured and scarred to the surrounding tissue.

The Procedure

Step 1

Anesthesia is accomplished with a two-step procedure. Begin by placing intradermal anesthesia with a 30-gauge, 0.5-inch-long needle into the skin directly overlying the cyst (see Local Anesthesia Administration). When the needle tip is correctly placed, there is resistance to injecting the anesthetic within the skin, and a bleb develops in the skin. In the second step, place a field block (see Field Block Anesthesia). 
  • PITFALL: If the needle tip is placed inadvertently within the cyst, the anesthetic will increase pressure and cause the cyst to explode, often shooting the sebaceous material across the room.

Step 2

Prep the area. Recommendations for performing skin preps are shown in Appendix E: Skin Preparation Recommendations. 
  • PEARL: When working on the scalp, lightly taping the hair back often facilitates the procedure.

Step 3

Create an entry into the cyst by vertically stabbing a no. 11 (sharp-pointed) scalpel blade into the cyst. Usually, a single up-and-down motion is sufficient to create the passage into the cyst. If the cyst is already expressing sebaceous material, use the scalpel to enlarge the opening as necessary. 
  • PEARL: Many operators fail to enter the cyst with the scalpel blade. By directing the blade toward the center of the cyst and inserting until a “give” is felt as the blade tip enters the cyst, the pass of the blade usually will be successful.

  • PITFALL: The clinician should not be positioned directly over the cyst. Opening a cyst that is under pressure can result in upward spraying of the cyst’s contents. Hold some gauze in the nondominant hand to act as a shield when opening the cyst.

Step 4

Alternately, some practitioners prefer the ease afforded by creating a larger opening. A 3- or 4-mm biopsy punch can be inserted directly down into the cyst. The comedone or pore usually is included in the skin that is removed with the biopsy punch. This opening allows much easier emptying of the cyst, but it has the disadvantage of requiring suture closure after the procedure. 

Step 5

The cyst contents must be emptied before attempting removal of the cyst wall. Using the thumbs to squeeze the cyst generally provides the greatest possible hand strength. Place the thumbs on opposite sides of the cyst opening. Press straight down with the greatest possible force, and firmly rotate the thumbs toward each other and then up toward the opening. 

Step 6

Squeezing out the cyst’s contents can cause the sebaceous material to erupt into the face of the practitioner. A more controlled process involves placing a hemostat into the cyst’s opening and squeezing the sebaceous material up into the open hemostat blades. Squeezing is accomplished using fingers on the nondominant hand. After the hemostat fills with material, it is withdrawn with the blades still open, and the sebaceous material is wiped away using gauze. The hemostat is reinserted and the process repeated. 

Step 7

Use gauze to wipe away sebaceous material on the skin surface. Continue vigorously squeezing until all material is removed. The “kneading” produced from the rocking motion of the thumbs toward the cyst opening helps to loosen the cyst from the surrounding subcutaneous and cutaneous attachments. Move the thumbs around the opening so that the vigorous massaging is performed on all sides of the cyst. 
  • PITFALL: Once the cyst contents have been squeezed out, a mass may be palpated adjacent to the cyst, suggesting that a tumor may be present. It is recommended that the minimal excision technique be abandoned for a formal excision and biopsy. If malignancy is discovered in a cyst wall that is removed at the time of the minimal excision technique, the physician may consider a second excision.

  • PEARL: Any atypical-appearing lesion or one associated with a palpable irregularity in the cyst wall should be sent for histologic analysis.

Step 8

After the entire site has been vigorously kneaded and the cyst is completely emptied, reach down through the opening and grasp the posterior wall of the cyst. Gently elevate the cyst toward the skin surface. A lateral rocking motion may be helpful. 
  • PEARL: If adhesions are present, they may be reduced by semisharp dissection using Iris scissors.

Step 9

If resistance is encountered, grasp the cyst wall with a second hemostat just below the initial hemostat application, coming from a horizontal plane. Continue to elevate with both hemostats. If more of the cyst wall slides through the skin opening, the first hemostat can be released and used to regrasp the cyst wall below the second hemostat. 
 

Step 10

An attempt is made to remove the entire cyst wall intact. If the cyst wall breaks, enter the skin opening and vigorously grasp in all directions until additional cyst wall is grasped and pulled out. The incision may be closed with simple or hemostatic sutures. 
  • PITFALL: If any cyst wall remains in the wound, the cyst will usually recur. It is critical that the entire cyst wall be removed. Sufficient preprocedure anesthesia should be administered to permit this vigorous tugging within the wound.

  • PITFALL: Occasionally, previous inflammation of the cyst causes scarring and tethering of the cyst wall to surrounding tissues. This usually prevents removal of the cyst wall by the minimal technique. If the operator is unable to remove the cyst wall using the minimal technique, the operator should convert to a standard removal, making a fusiform excision surrounding the skin opening.

    Step 10
    Step 10

Complications

  • Bleeding

  • Infection

  • Scar formation

  • Recurrence

Pediatric Considerations

Although epidermal cysts are rare in the pediatric population, when present, the removal process is the same. 

Postprocedure Instructions

Simple epidermal cysts that appear to be completely excised do not generally require follow-up, except for suture removal. If a recurrence is brought to the physician’s attention at a later date, standard surgical excision should be attempted. 
Instruct the patient to gently wash an area that has been stitched after 1 day but to not put the wound into standing water for 3 days. Have the patient dry the area well after washing and use a small amount of antibiotic ointment to promote moist healing. Recommend wound elevation to lessen swelling, reduce pain, and speed healing. Instruct the patient not to pick at, break, or cut the stitches. 

Coding Information and Supply Sources

Use the benign excision codes (11400 to 11446) for removal of these lesions. The code selected is determined by size and location of the lesion. The codes include local anesthesia and simple (one-layer) closure, although the codes can be used if the minimal incision technique is used and no suturing is required. 

Bibliography

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2008 MAG Mutual Healthcare Solutions, Inc.’s Physicians’ Fee and Coding Guide. Duluth, Georgia. MAG Mutual Healthcare Solutions, Inc. 2007.
 
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