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Disseminated superficial actinic porokeratosis
Other Resources UpToDate PubMed

Disseminated superficial actinic porokeratosis

Contributors: Noah Craft MD, PhD, Lindy P. Fox MD, Sarah Hocker DO, Susan Burgin MD, Lowell A. Goldsmith MD, MPH
Other Resources UpToDate PubMed


Porokeratosis is a disorder of keratinization characterized by a distinct peripheral, thin, ridge-like scale that corresponds histologically to a thin, angled column of epidermal parakeratotic cells that extends through the stratum corneum. Disseminated superficial actinic porokeratosis (DSAP) is a very common form of porokeratosis. The lesions are minimally elevated keratotic papules symmetrically distributed on sun-exposed sites. Patients with DSAP may complain of exacerbations during the summer months with increased pruritus or burning sensation.

DSAP is thought to have autosomal dominant inheritance with onset in the third or fourth decade of life. Women are affected 3 times more frequently than men. Risk factors for developing this disorder also include exposure to ultraviolet radiation and immunosuppression. Individuals with light skin phototypes are more prone to developing this disorder. Recently, mutations in the mevalonate kinase pathway have been identified in DSAP and are thought to be the pathogenetic basis of this disorder.

The potential for transformation to squamous cell carcinoma (SCC) exists but is rare.


L56.5 – Disseminated superficial actinic porokeratosis (DSAP)

41495000 – Disseminated superficial actinic porokeratosis

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Differential Diagnosis & Pitfalls

Although DSAP is distinct in its clinical appearance, it may still need to be differentiated from the following list of diseases:
  • Actinic keratosis have scale throughout the lesion, whereas in DSAP, scale forms a peripheral thin ridge.
  • Granuloma annulare
  • Lichen planus
  • Seborrheic keratosis have a more "stuck-on" appearance.
  • Tinea corporis – A potassium hydroxide (KOH) preparation may be performed to rule out this entity.
  • Flat wart

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Last Updated:01/13/2022
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Disseminated superficial actinic porokeratosis
A medical illustration showing key findings of Disseminated superficial actinic porokeratosis : Forearm, Photosensitivity, Sun-exposed distribution, Lower legs
Clinical image of Disseminated superficial actinic porokeratosis - imageId=662415. Click to open in gallery.  caption: 'A close-up of a flat, annular papule and a similar plaque, each with a peripheral hyperkeratotic, ridge-like scale.'
A close-up of a flat, annular papule and a similar plaque, each with a peripheral hyperkeratotic, ridge-like scale.
Copyright © 2024 VisualDx®. All rights reserved.