What is the treatment for an infected sebaceous cyst?

Treatment of Infected Sebaceous Cyst

Incision and drainage is the primary treatment for an infected sebaceous cyst, with antibiotics reserved only for patients showing systemic signs of infection. 1

Primary Management: Incision and Drainage

The cornerstone of treatment is incision and drainage with thorough evacuation of all purulent material. 1 This approach directly addresses the infected cyst and provides immediate relief.

Key Technical Points:

• Probe the cavity to break up any loculations or septations to ensure complete drainage 1
• Cover the surgical site with a simple dry dressing after drainage 1
• Do not pack the wound with gauze - studies demonstrate this increases pain without improving healing outcomes 1
• Gram stain and culture of the pus are not routinely recommended 1

Understanding the Pathophysiology:

The inflammation in sebaceous cysts typically results from rupture of the cyst wall with extrusion of contents into the dermis, rather than primary bacterial infection 1. This explains why drainage alone is usually sufficient.

When to Use Antibiotics

Systemic antibiotics are unnecessary unless the patient demonstrates signs of systemic infection or has markedly impaired host defenses. 1

Specific Criteria for Antibiotic Use:

Prescribe antibiotics only when any of the following are present:

• Temperature >38°C or <36°C 1
• Tachypnea >24 breaths per minute 1
• Tachycardia >90 beats per minute 1
• White blood cell count >12,000 or <4,000 cells/µL 1

Antibiotic Selection:

• When antibiotics are indicated, choose agents active against Staphylococcus aureus, the most common pathogen 1
• Consider local MRSA prevalence when selecting specific agents 2

Alternative Approach: One-Stage Excision

For appropriately selected cases, primary excision of the inflamed cyst with closure may be superior to conventional staged treatment. 3 A study of 166 patients demonstrated that one-stage excision followed by 5 days of antibiotics resulted in:

• Decreased duration of antibiotic exposure 3
• Reduced morbidity 3
• Lower overall cost 3

This approach avoids the need for a second procedure and may be considered when the patient can tolerate definitive excision 4, 3.

Management of Inadequate Drainage

If the infection persists or worsens after initial drainage, re-open the incision and ensure complete evacuation of all contents. 1 Incomplete drainage is a common pitfall that leads to treatment failure.

• Thoroughly probe the cavity again to break up any remaining loculations 1
• Ensure all purulent material is evacuated 1

Prevention of Recurrence

For recurrent infections at the same site, search for local causes such as retained foreign material or incomplete cyst wall removal. 1

• Consider complete excision of the cyst and its wall once acute inflammation has resolved 1
• This definitive approach prevents future episodes at the same location 1

Critical Pitfalls to Avoid

• Never close the wound without adequate drainage - this leads to recurrent infection 1
• Do not routinely prescribe antibiotics in the absence of systemic infection signs 1
• Avoid wound packing as it increases pain without benefit 1
• Do not perform routine cultures unless there are specific clinical indications 1