Treatment of Infected Epidermoid Cysts
The recommended treatment for an infected epidermoid cyst is incision and drainage, with thorough evacuation of the pus and probing of the cavity to break up loculations. 1
Primary Management Approach
Surgical Management (First-Line)
- Incision and drainage is the cornerstone of treatment for infected epidermoid cysts 1
- Complete removal of the cyst wall is essential to prevent recurrence 2
- The surgical site should simply be covered with a dry dressing after the procedure 1
- Some clinicians may pack the wound with gauze or suture it closed, though this is not always necessary 1
When to Consider Antibiotics
Systemic antibiotics are generally not necessary for most infected epidermoid cysts, but should be added in the following circumstances 1:
- Presence of systemic inflammatory response syndrome (SIRS):
- Temperature >38°C or <36°C
- Tachypnea >24 breaths per minute
- Tachycardia >90 beats per minute
- White blood cell count >12,000 or <400 cells/μL
- Extensive surrounding cellulitis
- Multiple lesions
- Cutaneous gangrene
- Severely impaired host defenses
- Severe systemic manifestations of infection (high fever)
Diagnostic Considerations
Laboratory Testing
- Gram stain and culture of pus from inflamed epidermoid cysts are not recommended 1
- The inflammation and purulence in infected epidermoid cysts typically occur as a reaction to rupture of the cyst wall and extrusion of its contents into the dermis, rather than as a primary infectious process 1
Clinical Assessment
- Infected epidermoid cysts typically present as painful, tender, and fluctuant red nodules, often surrounded by erythematous swelling 1
- They are usually filled with keratinous material and may have an epidermal punctum (a clinical diagnostic hallmark) 2
Special Considerations
Antibiotic Selection (When Indicated)
If antibiotics are deemed necessary based on the criteria above, they should cover Staphylococcus aureus:
- First-line options include penicillinase-resistant penicillins or first-generation cephalosporins 1
- For MRSA coverage or penicillin-allergic patients, consider doxycycline, clindamycin, or sulfamethoxazole-trimethoprim 1
Recurrent Infections
- For recurrent abscesses at the same site, search for local causes such as a pilonidal cyst, hidradenitis suppurativa, or foreign material 1
- Complete surgical excision of the cyst with its wall is crucial to prevent recurrence 2
Complications
- The complication rate of surgical treatment is relatively low (approximately 2.2%) 2
- Potential complications include infection, scarring, and recurrence if the cyst wall is not completely removed
Follow-up Care
- Simple wound care with dry dressing changes
- Monitor for signs of recurrence or inadequate drainage
- Consider definitive excision of the cyst wall if recurrence occurs
By following this approach, infected epidermoid cysts can be effectively managed with a low rate of complications and recurrence.