Skin - Nonmelanocytic tumors
Benign (nonmelanotic) epidermal tumors or tumor-like lesions
Acquired digital fibrokeratoma

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

Revised: 3 October 2016, last major update March 2015

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

PubMed Search: Acquired digital fibrokeratoma [title]

Cite this page: Acquired digital fibrokeratoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/skintumornonmelanocyticacquireddigitalfibrokeratoma.html. Accessed December 11th, 2016.
Definition / General
  • Acquired benign lesion of acral (limb or other extremity) skin
Terminology
  • Also known as acral fibrokeratoma and acquired periungual fibrokeratoma
Epidemiology
  • Middle aged adults
  • Men > women
Sites
  • Classically located on fingers and toes but can occur elsewhere on acral skin
Etiology
  • Etiology unknown
  • Trauma has been implicated but no studies have substantiated that hypothesis
Clinical Features
  • Skin colored, slow growing firm nodule, from a few millimeters to over 1 cm in size
  • Rare giant variants have been described (Ann Dermatol 2011;23:64)
  • Hyperkeratotic collarete at base is characteristic
  • May have prominent verruciform surface resembling a verruca or cutaneous horn
Case Reports
Treatment
  • Benign, although appearance or discomfort may prompt treatment
  • Excision is curative
Clinical Images

Images hosted on other servers:

Left great toe

Middle finger

Collarette of epidermis surrounds nodules

Solitary, projecting keratotic mass



Skin colored, pedunculated firm nodule protruding from right heel toward sole

Gross Description
  • Pedunculated to dome shaped nodule on acral skin
Micro Description
  • Polypoid lesion with variably hyperplastic epidermis covering a dermal proliferation composed of dense collagen fibers and variable amounts of mature fibroblasts, small blood vessels and elastic tissue (J Am Acad Dermatol 1985;12:816)
  • Thickened collagen in dermis is oriented predominantly in the vertical direction
  • Stellate stromal cells may be present
  • Covered by variably acanthotic epidermis with hyperkeratotic orthokeratosis
  • Lesion merges with adjacent normal dermis
  • Neural structures are absent or inconspicious
  • Lacks adnexal structures
Micro Images

Images hosted on other servers:

Dome shaped tumor

Collagen fibers perpendicularly arranged

Acanthosis and massive orthokeratosis

Thickened collagen



Hyperkeratosis and acanthosis

Proliferating fibroblasts and capillaries

Compact orthokeratosis

Various images



Polypoid dermal proliferation

Prominent dense collagen

Vertically oriented collagen fibers

Negative Stains
  • Non-contributory
Differential Diagnosis
  • Acrochordon: non acral location, pedunculated, less hyperkeratotic, less dense connective tissue
  • Hypertrophic scar: normal or atrophic epidermis, dermal band of fibroblasts and dense collagen, blood vessels oriented perpendicular to epidermis
  • Periungual fibroma (Koenen tumor): similar/identical histology, distinction is predominantly based on clinical findings (i.e. location, multiple lesions, patient with tuberous sclerosis); some have noted that periungual fibromas can have __
  • Supernumerary digit: has prominent neural structures (i.e. peripheral nerves or tactile corpuscles), sometimes cartilage/bone is present; most are related to the fifth digit