What is Dapsone (DSAP)?

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What is DSAP?

DSAP stands for Disseminated Superficial Actinic Porokeratosis, a rare autosomal dominant keratinization disorder characterized by multiple superficial keratotic lesions with raised hyperkeratotic borders and slightly atrophic centers, typically appearing on sun-exposed areas. 1, 2

Clinical Characteristics

  • Lesion morphology: Numerous annular papules with subtle raised hyperkeratotic borders and slightly atrophic centers, creating a distinctive appearance 2
  • Distribution: Primarily affects sun-exposed areas, particularly the extremities and trunk 3
  • Inheritance pattern: Usually inherited in an autosomal dominant fashion with genetic heterogeneity 2, 4

Pathophysiology

  • Clonal keratinocyte disorder: The leading hypothesis suggests multifocal expansion of atypical clones of keratinocytes, potentially unmasked by actinic (UV) damage 2
  • Genetic loci identified: Four susceptible loci have been mapped: 12q23.2-24.1, 15q25.1-26.1, 1p31.3-p31.1, 18p11.3, and a novel locus at 16q24.1-24.3 4
  • UV exposure as trigger: Chronic ultraviolet light exposure is considered an etiological factor, with cases reported following narrowband UVB therapy 3

Malignancy Risk

  • Squamous cell carcinoma development: There is an increased risk of cutaneous squamous cell carcinoma developing within DSAP lesions 2
  • Histologic atypia: Lesions often show keratinocytic atypia centrally, which may progress to malignancy 2
  • Immunosuppression as risk factor: Immunosuppression is a well-documented precipitant of porokeratosis and can cause rapid, widespread progression, as demonstrated in cases following bone marrow transplant induction therapy 2

Treatment Approach

  • Simvastatin 2%/cholesterol 2% cream: This represents a promising long-term targeted treatment showing significant improvement in disease severity (measured by Investigator Global Assessment) with most progress occurring in the first 3 months 1
  • Maintenance regimen: After initial daily application, tapering to a proactive approach twice weekly maintains disease control and may be important for skin tumor prevention 1
  • Quality of life improvement: Treatment significantly decreases Dermatology Life Quality Index (DLQI) scores within the first 3 months 1
  • Tumor prevention: No new skin tumors developed during 18 months of treatment with simvastatin/cholesterol cream 1

Critical Clinical Pitfalls

  • Avoid prolonged UV exposure: Given the actinic nature of DSAP, patients should minimize sun exposure and avoid phototherapy when possible, as cases have developed following narrowband UVB treatment for other conditions 3
  • Monitor immunosuppressed patients closely: Aggressive immunosuppression (such as bone marrow transplant conditioning) can trigger rapid, widespread development of DSAP within days 2
  • Surveillance for malignancy: Regular skin examinations are essential given the increased squamous cell carcinoma risk within DSAP lesions 2

Note: DSAP should not be confused with dapsone (a sulfone medication used for dermatitis herpetiformis and leprosy), despite the similar acronym. 5, 6

References

1
Research

Long-term disease control of disseminated superficial actinic porokeratosis (DSAP) with simvastatin 2%/ cholesterol 2% cream.

Journal der Deutschen Dermatologischen Gesellschaft = Journal of the German Society of Dermatology : JDDG, 2025

5
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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