Management of Disseminated Superficial Actinic Porokeratosis (DSAP)
For patients with Disseminated Superficial Actinic Porokeratosis (DSAP), a combination of UV protection and field-directed treatments with either topical 5-fluorouracil or imiquimod is recommended as first-line therapy, with treatment selection based on lesion characteristics, location, and patient factors.
Understanding DSAP
DSAP is a disorder of keratinization characterized by:
- Multiple small, brown plaques with elevated keratotic rims
- Typically occurs on sun-exposed areas (face, arms, legs)
- Female predominance, usually manifesting in third or fourth decades
- Chronic, relapsing condition with risk of malignant transformation
Treatment Algorithm
First-Line Approaches:
UV Protection (Strong recommendation) 1
- Essential for all patients with DSAP
- Reduces development of new lesions and progression of existing ones
Field-Directed Therapies (for multiple lesions):
Topical 5-fluorouracil (5-FU) (Strong recommendation) 1
- Most effective for thin lesions and high numbers of lesions
- Particularly effective on scalp, face, and hands
- Typical regimen: 0.5% cream once daily for 1-4 weeks
Topical imiquimod (Strong recommendation) 1
- Effective for multiple lesions on face, scalp
- Typical regimen: 5% cream 2-3 times weekly for 4-16 weeks
- Alternative: 2.5% or 3.75% cream daily for 2-3 weeks on/off cycles
Lesion-Directed Therapies (for isolated or resistant lesions):
- Cryosurgery (Strong recommendation) 1
- Best for low numbers of lesions
- Particularly effective for lesions on face, scalp, ears
- Cryosurgery (Strong recommendation) 1
Second-Line Approaches:
Diclofenac gel 3% (Conditional recommendation) 1, 2
- Moderate efficacy with good tolerability
- Better suited for lesions below the knee 1
Photodynamic therapy (PDT) (Conditional recommendation) 1, 3
- Consider for:
- Multiple or confluent lesions
- Areas of poor healing
- Lesions resistant to first-line therapies
- ALA-red light or daylight PDT preferred over blue light PDT
- Consider for:
Chemical peels 4
- Consider for refractory cases
- Glycolic acid 50% + salicylic acid 25% in two-layer technique
- Requires multiple treatments (approximately every 6 weeks)
Laser therapy 3
- Options include CO2 laser, fractional photothermolysis, and Q-switched ruby lasers
- Consider for resistant cases with minimal lesions
- Better side effect profile than PDT but limited evidence
Treatment Selection Based on Lesion Characteristics:
| Characteristic | Preferred Treatment |
|---|---|
| Low number of lesions | Cryosurgery, 5-FU |
| High number of lesions | 5-FU, imiquimod, PDT |
| Thin lesions | 5-FU, imiquimod, diclofenac |
| Hypertrophic lesions | Curettage, cryosurgery |
| Resistant isolated lesions | Curettage, biopsy |
Treatment Selection Based on Location:
| Location | Preferred Treatment |
|---|---|
| Face, scalp, ears | Cryosurgery, 5-FU, imiquimod |
| Periorbital | Cryosurgery, curettage (avoid topicals) |
| Confluent scalp | 5-FU, imiquimod (consider pre-treatment with 5% salicylic acid) |
| Below knee | Curettage, cryosurgery, diclofenac |
| Hands | Cryosurgery, 5-FU |
Monitoring and Follow-up
Regular follow-up is essential due to:
- Chronic, relapsing nature of DSAP
- Risk of malignant transformation
- Need to assess treatment response
Biopsy indicated for:
- Diagnostic uncertainty
- Failure to respond to appropriate therapy
- Lesions with concerning features (rapid growth, ulceration, bleeding)
Important Considerations and Pitfalls
- DSAP is often misdiagnosed as chronic UV damage or actinic keratoses, leading to years of ineffective treatment 4
- Treatment resistance is common - patients may require multiple therapeutic approaches
- Chronic management is typically necessary rather than expecting complete cure
- Malignant transformation risk necessitates ongoing surveillance
- Treatment expectations should be realistic - focus on control rather than complete clearance