What is the best course of treatment for a patient with an epidermoid cyst?

Treatment of Epidermoid Cysts

Incision and drainage is the definitive treatment for inflamed epidermoid cysts, while complete surgical excision is the treatment of choice for non-inflamed cysts. 1

Inflamed Epidermoid Cysts

Primary Treatment Approach

• Incision and drainage is the recommended treatment for inflamed epidermoid cysts, carbuncles, abscesses, and large furuncles 1
• The procedure requires thorough evacuation of all purulent material and probing the cavity to break up loculations 1
• Simply covering the surgical site with a dry dressing is the most effective wound management approach 1
• Packing the wound with gauze causes more pain without improving healing outcomes and should be avoided 2

When Antibiotics Are NOT Needed

• Gram stain and culture of pus from inflamed epidermoid cysts are not recommended 1
• Systemic antibiotics are rarely necessary for typical inflamed epidermoid cysts 1
• The inflammation and purulence occur as a reaction to rupture of the cyst wall and extrusion of its contents into the dermis, rather than as an infectious complication 1

When Antibiotics ARE Indicated

Systemic antibiotics directed against S. aureus should be administered only when: 1, 2

• Multiple lesions are present
• Extensive surrounding cellulitis exists (erythema >5 cm from incision with induration)
• Systemic signs of infection are present (fever ≥38°C, WBC >12,000)
• The patient has severely impaired host defenses or is immunocompromised
• Cutaneous gangrene is present

Non-Inflamed Epidermoid Cysts

Surgical Excision Techniques

• Complete surgical excision is the treatment of choice for non-inflamed epidermoid cysts to prevent recurrence 3, 4
• The cyst wall must be removed completely to avoid relapses 4
• Most cases can be performed under local anesthesia with a low complication rate of approximately 2.2% 4

Minimal Excision Technique

For appropriate candidates, a less invasive approach includes: 3

• Making a 2- to 3-mm incision
• Expressing the cyst contents through compression
• Extracting the cyst wall through the incision
• No suture closure required
• Using gauze or a splatter shield to protect from spraying cyst contents

Timing Considerations

• Inflamed cysts are difficult to excise, and it is preferable to postpone definitive excision until inflammation has subsided 3
• Perform incision and drainage first for inflamed cysts, then consider complete excision once inflammation resolves

Common Pitfalls to Avoid

Inadequate Initial Drainage

• Inadequate initial drainage is the most common cause of treatment failure and recurrence 2
• Failure to thoroughly evacuate all purulent material during initial I&D leads to persistent drainage 2
• Loculations or septations within the cyst must be broken up by probing the cavity 1, 2

Inappropriate Antibiotic Use

• Do not prescribe antibiotics without addressing the mechanical problem - antibiotics alone without adequate drainage will fail 2
• Do not assume antibiotics are needed for routine inflamed epidermoid cysts 1

Wound Management Errors

• Do not pack the wound unnecessarily as this increases pain without improving outcomes 2
• Do not close the wound without ensuring complete drainage, as this leads to recurrent infection 2

Special Considerations

Histologic Evaluation

• Histologic evaluation is necessary only if unusual findings or clinical suspicion of malignancy is present 3
• The rarity of associated cancer makes routine pathology unnecessary for typical cases 3

Persistent Drainage

If drainage persists beyond 2-3 weeks post-procedure: 2

• Re-open the incision and ensure complete evacuation of all contents
• Probe the cavity thoroughly to break up any remaining loculations
• Search for retained foreign material or cyst contents
• Cover with dry sterile dressing rather than packing