Skin - Nonmelanocytic tumors
Benign (nonmelanotic) epidermal tumors or tumor-like lesions
Pseudoepitheliomatous hyperplasia

Reviewer: Hillary Elwood, M.D. (see Authors page)

Revised: 30 September 2015, last major update September 2015

Copyright: (c) 2003-2015,, Inc.

PubMed Search: Pseudoepitheliomatous hyperplasia [title]
Definition / General
  • Pseuodepitheliomatous (pseudocarcinomatous) hyperplasia (PEH) is a histologic pattern, not a specific diagnosis
  • Histologic mimic of squamous cell carcinoma
  • PEH occurs in a wide range of settings such as:
    • Chronic irritation, including borders of ulcers and healing wounds, urostomy/colostomy sites, prior biopsy site, stasis ulcer, pyoderma gangrenosum, prurigo nodularis, lichen simplex chronicus, halogenoderma
    • Inflammatory dermatoses such as hypertrophic lichen planus, pemphigus vegetans, chronic arthropod bite
    • Infectious dermatoses such as tuberculosis verrucosa cutis, pyoderma vegetans, atypical mycobacterial infection, deep fungal infection
    • Overlying tumors such as granular cell tumor, cutaneous T cell lymphoma, CD30+ lymphoproliferative disorders, Spitz nevi, melanoma
  • Differential for PEH with intraepidermal neutrophilic microabscesses includes:
  • Case Reports
  • 51 year old woman with vulvar pseudoepitheliomatous hyperplasia associated with herpes simplex virus type II (J Obstet Gynaecol Res 2014;40:255)
  • Pseudocarcinomatous hyperplasia in anaplastic large cell lymphoma (J Cutan Pathol 2015 Jun 3 [Epub ahead of print])
  • Pseudoepitheliomatous hyperplasia mimicking invasive squamous cell carcinoma in NK/T cell lymphoma (Histopathology 2015;67:404)
  • Desmoplastic trichoepithelioma with pseudocarcinomatous hyperplasia (J Cutan Pathol 2015;42:102)
  • Pseudocarcinomatous hyperplasia involving the ear from gout (J Cutan Pathol 2014;41:42)
  • Micro Description
  • Prominent acanthosis of epidermis and adnexal epithelium with deep, somewhat bulbous, downgrowths of epithelial cells that may appear invasive
  • Dermal fibrosis and reactive vascular proliferation may be present
  • In cases associated with an inflammatory or infectious process, there may be intraepidermal microabscesses
  • Often associated with trapping of elastic fibers within epidermis
  • Absent or minimal atypia, rare mitoses
  • Micro Images
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    Inflammatory infiltrate in dermis

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    Pseudo-epitheliomatous hyperplasia

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    Surface epithelium

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    Acanthotic squamous epithelium

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    Mild chronic inflammation

    Differential Diagnosis
  • Pseudoepitheliomatous hyperplasia can be seen in a number of settings, as outlined above, and its presence should prompt a search for an underlying infectious process, inflammatory process or tumor as appropriate
  • Well differentiated squamous cell carcinoma:
    • Can be extremely difficult to impossible to distinguish PEH from squamous cell carcinoma (SCC), especially on superficial shave biopsies
    • PEH is mainly differentiated by clinical findings and / or the discovery of an underlying reason for its presence
    • Findings that favor SCC include increased mitoses particularly atypical mitoses, more pronounced cytologic atypia, perineural / lymphovascular invasion