Skin nonmelanocytic tumor
Fibrous, fibrohistiocytic and myofibroblastic neoplasms
Acquired digital fibrokeratoma

Topic Completed: 1 March 2015

Minor changes: 14 March 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Acquired digital fibrokeratoma [title]

Hillary Rose Elwood, M.D.
Page views in 2019: 9,848
Page views in 2020 to date: 5,305
Cite this page: Elwood HR. Acquired digital fibrokeratoma. website. Accessed September 21st, 2020.
Definition / general
  • Acquired benign lesion of acral (limb or other extremity) skin
  • Also known as acral fibrokeratoma and acquired periungual fibrokeratoma
  • Middle aged adults
  • Men > women
  • Classically located on fingers and toes but can occur elsewhere on acral skin
  • 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
  • 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
Microscopic (histologic) 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
Microscopic (histologic) 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
  • Noncontributory
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 prominent stellate atypical myofibroblasts, may have a more prominent vascular component, and may lack the epidermal changes of digital fibrokeratoma (Arch Dermatol 1995;131:1465)
  • 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
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