Skin nonmelanocytic tumor

Benign (nonmelanotic) epidermal tumors or tumor-like lesions

Epidermolytic acanthoma


Resident / Fellow Advisory Board: Caroline I.M. Underwood, M.D.
Editorial Board Member: Kiran Motaparthi, M.D.
Simon F. Roy, M.D.
Jennifer M. McNiff, M.D.

Topic Completed: 18 October 2021

Minor changes: 18 October 2021

Copyright: 2021, PathologyOutlines.com, Inc.

PubMed Search: Epidermolytic acanthoma

Simon F. Roy, M.D.
Jennifer M. McNiff, M.D.
Page views in 2020: 119
Page views in 2021 to date: 2,045
Cite this page: Roy SF, McNiff JM. Epidermolytic acanthoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumornonmelanocyticepidermolyticacanthoma.html. Accessed December 3rd, 2021.
Definition / general
  • Cutaneous acanthotic benign lesion with epidermolytic hyperkeratosis spanning more than 50% of its surface
Essential features
  • Solitary or multiple lesions with acanthosis and epidermolytic hyperkeratosis
  • Epidermolytic hyperkeratosis spanning > 50% of the lesion surface
ICD coding
  • ICD-10: D23.9 - other benign neoplasm of skin, unspecified
  • ICD-11: 2F21.Y - other specified benign keratinocytic acanthomas
Epidemiology
Sites
  • Extragenital (67% of cases): head and neck, upper limbs, trunk or back, lower limbs (uncommon), oral (uncommon)
  • Genital (33% of cases): vulvar, penile, perianal, perineal, scrotal
Pathophysiology
Clinical features
  • Most frequently a single lesion but may be multiple (5% of instances) (J Cutan Pathol 2019;46:305)
  • Erythematous, skin colored or brown papules or nodules with scale
  • Multiple epidermolytic acanthomas are more likely to be found on genital sites
  • May be pruritic
  • Dermoscopy may show pearly white areas, irregular pigmented grooves and peripheral pigmented radial streak-like areas (J Am Acad Dermatol 2017;77:e37)
Diagnosis
  • H&E stain with light microscopy
Prognostic factors
  • Benign
Case reports
Treatment
Clinical images

Contributed by Simon F. Roy, M.D. and Jennifer M. McNiff, M.D.
Solitary epidermolytic acanthoma

Solitary epidermolytic acanthoma



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Multiple epidermolytic acanthomas on scrotum

Multiple epidermolytic acanthomas on scrotum

Gross description
Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Simon F. Roy, M.D. and Jennifer M. McNiff, M.D.
Papillomatous pattern of epidermolytic acanthoma Papillomatous pattern of epidermolytic acanthoma

Papillomatous pattern

Cup-like / endophytic pattern Cup-like / endophytic pattern

Cup-like / endophytic pattern

Positive stains
  • Not usually performed
Videos

Epidermolytic hyperkeratosis

Sample pathology report
  • Skin, left forearm, punch biopsy:
    • Epidermolytic acanthoma
Differential diagnosis
  • Seborrheic keratosis:
    • Acanthosis and papillomatosis but no epidermolytic hyperkeratosis
    • Focal incidental epidermolytic hyperkeratosis may be present
      • Still classified as seborrheic keratosis if covering < 50% of the surface
  • Verruca or condyloma:
    • Hypergranulosis and finely speckled keratohyaline granules
    • No lace-like reticular degeneration
    • No dense cytoplasmic eosinophilia
    • HPV induced
  • Incidental epidermolytic hyperkeratosis in another acanthotic lesion:
    • Epidermolytic hyperkeratosis is found spanning < 50% of the lesion surface
  • Epidermolytic ichthyosis (formerly bullous congenital icthyosiform erythroderma):
    • Generalized desquamating plaques rather than a solitary lesion
    • Hereditary ichthyosiform condition due to alterations in keratin genes
    • Overlapping histology with solitary epidermolytic acanthoma, clinicopathologic correlation is crucial
  • Clear cell acanthoma:
    • Pale epithelial cells with acanthosis but no epidermolytic hyperkeratosis
  • Solitary keratosis with hypergranulotic dyscornification:
    • Dense keratohyaline granules rather than finely speckled
    • Both may display eosinophilic cytoplasm but perinuclear vacuolization is more characteristic of epidermolytic acanthoma
    • Hypergranulotic dyscornification may be a focal incidental finding in other lesions
Board review style question #1


What is the best diagnosis based on the images above, considering this is a solitary lesion?

  1. Clear cell acanthoma
  2. Epidermolytic acanthoma
  3. Epidermolytic ichthyosis
  4. Seborrheic keratosis
Board review style answer #1
B. Epidermolytic acanthoma. Epidermolytic acanthoma is an acanthotic benign lesion that displays epidermolytic hyperkeratosis on more than 50% of its surface. Clear cell acanthoma and seborrheic keratosis do not show epidermolytic hyperkeratosis on their surface. Epidermolytic ichthyosis does not present as a solitary lesion but rather as a hereditary generalized desquamative eruption.

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Reference: Epidermolytic acanthoma
Board review style question #2

What is the histopathological epidermal reaction pattern in the image above?

  1. Acantholysis
  2. Dyskeratotic acantholysis
  3. Epidermolytic hyperkeratosis
  4. Epidermal necrosis
Board review style answer #2
C. Epidermolytic hyperkeratosis. Epidermolytic hyperkeratosis is the epidermal reaction pattern displayed here, with reticular (lace-like) clearing of the epidermis, dense eosinophilia of the keratocytes and coarse keratohyaline granules. Acantholysis is rather a rounded of keratinocytes with detached intercellular attachments (desmosomes). Dyskeratotic acantholysis shows acantholysis in addition to dense eosinophilia of keratinocytes but no reticular degeneration of finely speckled keratohyaline granules.

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Reference: Epidermolytic acanthoma
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