Papulosquamous disorders

Papulosquamous disorders 

Updated: 02/10/2021

© Jun Wang, MD, PhD

General features
  • Papulo-: Papules and plaques
  • Squamous: Scaly
  • Common skin diseases with dermal inflammation and epidermal hyperkeratosis or desquamation
  • Histological features may be seen in other conditions such as infections, premalignant and malignant dermatoses
  • Drug eruption and dermatophytosis may cause same clinical presentations
Koebner phenomenon
  • New skin lesion on areas of cutaneous injury, also known as isomorphic response
  • May be associated with psoriasis and lichen planus
  • Same clinical and histological features as original lesions
  • NOT due to the seeding of an infectious agent, an allergic reaction to a contact agent, or skin breakdown
  • May form with or without pre-existing skin conditions
  • Confirmed by experimentally reproducing lesions with injury
  • “All or nothing” response:
Patients who develop Koebner phenomenon in response to one method of injury are susceptible to other stimuli
A patient who does not develop skin lesions with one type of injury is NOT expected to exhibit Koebner phenomenon with another type of injury
Entities to be discussed

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