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Eruptive squamous atypia
Other Resources UpToDate PubMed

Eruptive squamous atypia

Contributors: Casey P. Schukow DO, Susan Burgin MD
Other Resources UpToDate PubMed

Synopsis

Eruptive squamous atypia (ESA) is a distinct entity characterized by the presence of one or more scaly or crusted papules, plaques, or nodules that display a proliferation of well-differentiated, atypical keratinocytes on histopathology. ESA is also commonly referred to as eruptive keratoacanthoma (eruptive KA). However, this term is a misnomer as "keratoacanthoma" implies squamous cell carcinoma (SCC), whereas ESA represents reactive squamous proliferation.

ESA can be subcategorized into 2 morphologic types. The first type is focal koebnerizing ESA (FK-ESA), which appears as a hyperkeratotic papule or plaque that arises in areas of localized skin trauma, such as surgery, laser therapy, or tattoo application. The second type is diffuse ESA (D-ESA), which presents as multifocal ESA lesions, often on the arms or legs.

Both patterns may occur simultaneously. A skin biopsy should be used to confirm the diagnosis.

Codes

ICD10CM:
L85.8 – Other specified epidermal thickening

SNOMEDCT:
69740004 – Squamous cell atypia

Look For

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Squamous cell carcinoma (SCC)
  • Solitary KA
  • Prurigo nodularis
  • Generalized eruptive KA of Grzybowski – Thousands of skin papules may appear with mucous membrane involvement
  • Multiple self-healing squamous epithelioma (Ferguson-Smith disease) – Multiple and spontaneously regressing KAs, usually begin in the third decade of life in sun-exposed skin areas
  • Pemphigoid nodularis
  • Foreign body reaction

Best Tests

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Management Pearls

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Therapy

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Drug Reaction Data

Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.

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References

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Last Reviewed:02/13/2022
Last Updated:02/16/2022
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Eruptive squamous atypia
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A medical illustration showing key findings of Eruptive squamous atypia : Dorsum of hand, Erythema, Lower leg, Scaly papule/plaque
Copyright © 2022 VisualDx®. All rights reserved.