Skin nonmelanocytic tumor
Benign (nonmelanotic) epidermal tumors or tumor-like lesions
Epidermal nevus
Author: Hillary Rose Elwood, M.D.
Last author update: 1 May 2016
Last staff update: 26 July 2023 (update in progress)
Copyright: 2003-2023, PathologyOutlines.com, Inc.
PubMed Search: Epidermal nevus [title]
Table of Contents
Definition / general | Clinical features | Case reports | Microscopic (histologic) description | Microscopic (histologic) images | Differential diagnosisCite this page: Elwood H. Epidermal nevus. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumornonmelanocyticepidermalnevus.html. Accessed October 3rd, 2023.
Definition / general
- Benign, congenital, hamartomatous malformation of epidermal cells
- Other types of epidermal nevi exist, consisting of malformation of adnexal epithelium, sometimes termed “organoid type” of epidermal nevus (see nevus sebaceus)
Clinical features
- 1 - 3 per 1000 live births, males = females, usually congenital, sometimes appears in children later in life
- Usually presents as localized verrucous papules to plaques, often on the extremities, trunk, head and neck
- Other presentations are possible, with linear, one-sided, and extensive variants described
- Most often a localized and incidental finding but may also present with extracutaneous abnormalities or may be seen in association with one of multiple syndromes (e.g. KID, CHILD, Gardners, etc)
- Epidermal nevus syndrome
- Association of epidermal nevus with skeletal, neurologic, ophthalmic abnormalities
Case reports
- 5 year old Mexican girl with systematized epidermal nevus (Am J Med Genet A 2008;146A:2275)
- 4 year old boy with keratinocytic epidermal nevus syndrome with schwann cell proliferation, lipomatous tumor, and mosaic KRAS mutation (BMC Med Genet 2015;16:6)
Microscopic (histologic) description
- Hyperkeratosis with broad low papillomatosis and acanthosis
- Pathology often identical to papillomatous seborrheic keratosis
- Can have slight increase in basal melanin pigment
- Sometimes epidermolytic hyperkeratosis is present within the lesion
- Numerous rare histologic patterns have been described within epidermal nevi such as acanthosis - nigricans - like, hailey - hailey - like, acantholytic dyskeratosis, others
Microscopic (histologic) images
Images hosted on other servers:
Typical histologic features
of hyperkeratosis,
acanthosis and
papillomatosis
Differential diagnosis
- Acanthosis nigricans: Usually has less hyperkeratosis and papillomatosis than typically seen in epidermal nevus, but there are acanthosis nigricans-like variants of epidermal nevus
- Confluent and reticulated papillomatosis of Gougerot and Carteaud (CARP): Papillomatous architecture usually more subtle and sometimes absent
- Epidermal nevus can resemble other proliferations with papillomatous epidermal architecture, and clinical information is often necessary to make the distinction
- Seborrheic keratosis: Often has identical histology; Consider an epidermal nevus if a lesion resembles a seborrheic keratosis but is in a child or young individual, or is described as a congenital lesion
- Verruca vulgaris
