Skin - Nonmelanocytic tumors
Premalignant or noninvasive
Actinic keratosis

Author: Christopher Hale, M.D. (see Authors page)

Revised: 13 October 2016, last major update June 2012

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Actinic keratosis [title]

Cite this page: Actinic keratosis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skintumornonmelanocyticactinickeratosis.html. Accessed December 9th, 2016.
Definition / General
  • Also called solar keratosis, senile keratosis
  • Buildup of excessive keratin due to chronic exposure to sunlight
  • On sun-exposed sites (face, arms, dorsum of hands)
  • Called actinic cheilitis in lips
  • May become invasive with only a single layer of atypical keratinocytes

Risk factors:
  • Fair skin, ionizing radiation, hydrocarbon or arsenic exposure, renal transplant

Variants:
  • Acantholytic: lack of intercellular adhesion with clefts containing rounded, acantholytic cells
  • Atrophic: epidermis has only 3 - 4 layers of keratinocytes
  • Basaloid:
  • Bowenoid: full thickness atypia
  • Epidermolytic: vacuolar changes of keratinocytes at upper spinous and granular layers with coarse keratohyalin granules
  • Hyperkeratotic: with cutaneous horn
  • Pagetoid:
  • Pigmented: resembles solar lentigo, which lacks atypia and has downward projections
Case Reports
  • 54 year old man with inflammation of actinic keratosis due to alkylating agents for lung cancer (Cases J 2009 Jul 2;2:6946)
Treatment
  • Curettage, cryotherapy, topical chemotherapeutic agents (Imiquimod, 5-FU)
Clinical Images

Images hosted on Flickr:

Courtesy of Dr. Ha Do

Gross Description
  • Tan-brown, red or skin colored, circumscribed lesions, sandpaper texture
  • May have cutaneous horn (due to excessive production of parakeratotic scale)
Micro Description
  • Basal cell and squamous layer atypia and disorderly maturation, hyperkeratosis, parakeratosis
  • May have atrophy of epidermal surface
  • Usually no granular layer except at follicular orifices
  • Elastosis and often chronic inflammation of dermis
  • Follicular apparatus and intraepidermal sweat duct are spared
  • May have coexisting melanocytic atypia
Micro Images

Images hosted on other servers:

Various images

Positive Stains
Differential Diagnosis