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Acquired Digital Fibrokeratoma

Editor: Noureddine Litaiem Updated: 8/17/2023 10:49:03 AM


Acquired digital fibrokeratoma (ADFK) is a relatively rare and benign fibrous tumor.[1][2] The condition was first reported in 1968 by Bart et al, who noted multiple cases of this uncommon tumor on the fingers.[3] While ADFK typically occurs on the fingers, it can also occur on other acral surfaces, such as the heel, toes, palms, and soles. Therefore, it is often referred to as acral fibrokeratoma.[4][5][6] 

Clinically, ADFK presents as a small solitary papule surrounded by a characteristic hyperkeratotic collarette. The differential diagnosis usually includes a rudimentary supernumerary digit and the common wart when diagnosing this condition.[7][8] The treatment of choice is surgical tumor excision, as ADFK does not show spontaneous regression.


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The etiology of acquired digital fibrokeratoma remains unclear though it has been proposed that trauma or chronic irritation may be associated with its development, especially in the acral areas.[9] Specifically, repetitive trauma to a single site is believed to contribute to ADFK. This explains why the acral regions, predisposed to significant trauma on a day-to-day basis, are more commonly affected areas.[10] 

Histopathologic studies have revealed the presence of densely packed collagen fibers in affected areas, suggesting that collagen deposition by new fibroblasts may play a role in the etiology.[10]  

However, most patients do not report a known history of trauma to the site of ADFK.[10] As a result, there are 2 other prevailing theories for the etiology of this condition.

The first theory proposes an infectious origin as a possible cause. There have been reports of 2 cases where ADFK developed after a staphylococcal infection, particularly caused by Staphylococcus aureus.[11][12] This may suggest that a proliferative fibroblast response triggered by an infection may lead to the same histopathologic findings associated with trauma in the development of ADFK.

Another theory suggests that the condition may result from a proliferative benign neoplasm. Evidence of factor XIIIa staining in the dermis, much like dermatofibroma, supports this theory.[10] Interestingly, there has been a documented case where ADFK occurred concurrently with gingival overgrowth following cyclosporin treatment.[13]


Acquired digital fibrokeratoma is a rarely reported tumor, and its actual incidence is still unknown. Most publications on this condition consist of individual case reports, with authors often highlighting the lesions’ unusual size, location, or association with other conditions. However, a few case series have been published, with the most significant case including 50 patients.[1]

Documented cases of ADFK appear in patients of all racial backgrounds, and reports exist in German, Polish, Japanese, French, and Indian literature.[7] Males appear to be more affected than females, and the age range for ADFK is reported to be between 12 to 70 years, with a higher likelihood of occurrence in middle-aged adults.[7]


The pathophysiology of ADFK remains unclear. Histological examination of the tumor reveals denser fibers than normal skin and contains more fibroblasts and coarser elastic fibers. Therefore, the presumption is that ADFK results from the neoformation of collagen by fibroblasts.[5][7] 

Nemeth and Penneys reported that factor Xllla, present in fibrovascular tumors, is also found in ADFK.[14] Furthermore, collagen synthesis may undergo regulation by factor Xllla-positive dermal dendrocytes, which are increased in ADFK. This suggests that factor Xllla may be predominant in the fibroblastic reaction associated with ADFK.[10]

In cases of post-staphylococcal ADFK, it has been demonstrated that Staphylococcus aureus enterotoxin B can enhance fibroblast migration.[15]


Excisional biopsy is considered the gold standard for diagnosing acquired digital fibrokeratoma. Histopathological examination of the biopsy specimen typically reveals a very hyperkeratotic and acanthotic epidermis, accompanied by thick collagen bundles oriented vertically in the dermis.

The dermal core of an ADFK presents 1 of 3 histological variants, as characterized by Kint et al.[1] Type I is the most common variant, which presents as a dome-shaped lesion and consists of a dermal core of thick, densely packed collagen bundles with fine elastic fibers.[1] Type II is a tall, hyperkeratotic tumor with more fibroblasts arranged in the cutis than in the first type. It also exhibits reduced elastic fibers.[1] Type III is the least common variant. Type III presents as a flat to dome-shaped lesion with a poorly cellular dermal core, edematous structures, and the absence of elastic fibers.[1]

History and Physical

In most cases, acquired digital fibrokeratoma presents as an asymptomatic protuberance that does not spontaneously regress.[5] Clinically, it appears as a solitary, skin-colored, well-defined papule with a characteristic hyperkeratotic collarette at its base.[16] It primarily occurs on the fingers and toes but can also be found in other areas such as the lower lip, nose, elbow, pre-patellar area, and periungual tissue.[1][7] The lesion size is generally smaller than 1 cm, but there have been reported cases of ADFKs larger than 1 cm, referred to as giant ADFKs.[4][7]

A variant of ADFK is known as multibranched acquired periungual fibrokeratoma (MAPFK), which has been documented in the literature. In MAPFK, multiple filiform papules along the cuticle resemble warts associated with human papillomavirus (HPV).[10] 

Dermoscopy has been used to examine these lesions. Dermoscopy has shown filiform structures and significant variability in the dermoscopic findings due to possible vascular involvement and collagen fiber buildup within the lesions.[10]


The dermoscopic features of acquired digital fibrokeratoma have been rarely investigated and may differ among ADFK cases. Rubegni et al. described a central homogeneous pale-yellow core fringed by a hyperkeratotic white scaly collarette.[10][17] These features may reflect epidermal acanthosis, hyperkeratosis, and the presence of dense collagen fibers. A whitish-yellow area with dotted vessels was observed in the periphery, while globular vessels encircled the whole tumor externally.[17]

Hayashi et al reported the presence of red-clumped structures divided by white meshwork-like keratotic septa. These findings may correspond to the histological retraction of the epidermis.[10][18]

Treatment / Management

Various therapeutic options for ADFK, including cryotherapy, shave excision, curettage, and cauterization, are reported. However, surgical excision is considered the most effective and primary treatment modality. The tumor should be excised from its basal attachment to prevent the risk of recurrence.[19][20] (B3)

Lesions involving the nail plate may require the removal of the nail plate or other surgical intervention. In such instances, a dermatologist, Mohs micrographic surgeon, or other professional experienced in nail surgery may be necessary.[10]

Acquired digital fibrokeratoma has been associated with various conditions and factors. Infection caused by Staphylococcus aureus has been implicated in some cases, as well as an association with leprosy, particularly in individuals with reduced sensation.[10][21][22] (B2)

ADFK has been associated with other conditions, such as brain infarction, cyclosporine use in a renal transplant patient, pyogenic granulomas, pityriasis amiantacea, and psoriasis vulgaris.[10] However, many of these associations may result from trauma to the affected areas due to skin-picking behavior, and the associations are not fully understood.

Due to its histological resemblance to Koenen tumor, there have been discussions regarding a possible association between ADFK and tuberous sclerosis. While there are no clear guidelines regarding this association, it is suggested that patients with multiple lesions consistent with ADFK may warrant a cautious evaluation for other signs of tuberous sclerosis.[10]

Differential Diagnosis

Correctly identifying cutaneous lesions that mimic acquired digital fibrokeratoma is crucial to ensure appropriate and timely treatment. The differential diagnosis of ADFK includes the following:[7][8][23]

  • Supernumerary digit, a common hereditary limb malformation, is found at the base of the fifth finger. Histologically, rudimentary polydactyly differs from ADFK by the presence of nerve bundles and neuroid elements.[6] ADFK can often be mistaken as a supernumerary digit, as demonstrated in a reported case by  M. Ali et al., in which the histological report confirmed ADFK of the big toe.[7]
  • Verruca vulgaris, commonly known as warts, is the most frequently occurring neoplasm of the hand and fingers. It is caused by human papillomavirus (HPV) types 1, 2, 4, and 29.[24] Clinically, common warts exhibit a pattern of tiny black dots known as thrombosed capillaries.[25] Yu and Morgan reported a case in which ADFK was misdiagnosed as common warts and recurred after cryotherapy.[8]
  • A cutaneous horn is a clinical diagnosis referring to an exophytic and hyperkeratotic growth containing a column of keratin. Histological examination may reveal an underlying premalignant or malignant process. Cutaneous neurofibromas are benign tumors that may clinically resemble ADFK. They present as soft, polypoid, dome-shaped tumors on the skin.[26] Histological examination shows loosely spaced spindle cells, wavy collagenous strands, and a myxoid matrix.[5][27]
  • Superficial acral fibromyxoma, also known as digital fibromyxoma, is another condition that can present as a well-circumscribed dome-shaped asymptomatic papule on the digits. Histologically, it shares similarities with ADFK.[10][28][29]  However, digital fibromyxoma is likely to exhibit higher cellularity, and immunohistochemical staining for CD34 or CD99 is positive, while it is negative for ADFK.[28][29] Koenen tumor, also referred to as periungual fibroma, displays similar histological features to ADFK and may be a variant of ADFK or its own lesion. However, Koenen tumor has been associated with tuberous sclerosis.[23][30][31]
  • Eccrine poroma may appear on the palms and soles as a tan-to-pink exophytic papule, though histologically, it will show cuboid cell proliferation (as it is an adnexal tumor) with intercellular bridges, unlike ADFK.[10][23]
  • Pyogenic granuloma is a well-known vascular tumor that usually occurs in areas of minor trauma.[32] Clinically, it presents as a friable, dome-shaped, or pedunculated nodule with a scaly collarette. Other conditions such as dermatofibroma, papillary digital adenocarcinoma, or keratoacanthoma should also be considered when considering the differential diagnosis.[10]


Acquired digital fibrokeratoma is a benign tumor with no known risk of malignant transformation. Surgical excision is generally curative and carries a low risk of pain, bleeding, and infection.

After surgical treatment, patients can expect excellent functional recovery and a satisfying cosmetic outcome. With appropriate surgical management, the likelihood of the lesion reappearing is minimal.[20]


While ADFK generally does not lead to severe complications, there is a rare variant called periungual fibrokeratoma that may cause nail plate deformity and affect the function of the digit.[16]

Deterrence and Patient Education

The exact cause of ADFK is unknown. Therefore, no specific preventative measures can be taken to avoid its development. Patient education should include postoperative instructions to reduce the risk of complications such as infections.

Enhancing Healthcare Team Outcomes

Most patients with concerns about skin lesions first present to primary healthcare professionals. However, due to the vast number of skin lesions, it is essential to collaborate with a dermatologist when faced with an unknown or concerning skin lesion.

Dermatologists have specialized training and expertise in diagnosing and treating skin conditions, including differentiating between benign and potentially malignant lesions. Consulting with a dermatologist can provide valuable insights and guidance in accurately diagnosing and managing skin lesions, especially in cases where there is uncertainty or suspicion of malignancy.

Acquired digital fibrokeratoma is commonly diagnosed based on history and physical examination. Clinicians must be familiar with the various presentations of ADFK and be able to differentiate it from other skin conditions. Microscopic assessment and histological examination are necessary to confirm the diagnosis and identify histological variants.

Management of ADFK often involves surgical intervention with complete excision of the lesion performed by a dermatologist or a plastic surgeon. During the postoperative period, nurses are critical in providing incision care and monitoring for any signs of complications. Additionally, pharmacists collaborate effectively, as appropriate pain management significantly affects the patient's quality of life.

Pharmacists and nurses should remain aware during the treatment and follow-up process. If they detect any treatment failures or issues that may affect patient outcomes, they should report their concerns to the treating clinician. 

Despite ADFK being a benign lesion, the principles of interprofessional team dynamics are essential. The involvement of clinicians, dermatologists, plastic surgeons, nurses, and pharmacists, among others, ensures comprehensive care and promotes better patient outcomes.


(Click Image to Enlarge)
Illustration of Acquired Digital Fibrokeratoma on toe.
Illustration of Acquired Digital Fibrokeratoma on toe.
Contributed by Chelsea Rowe

(Click Image to Enlarge)
Acquired Digital Fibrokeratoma on index finger.
Acquired Digital Fibrokeratoma on index finger.
Contributed by Chelsea Rowe



Kint A, Baran R, De Keyser H. Acquired (digital) fibrokeratoma. Journal of the American Academy of Dermatology. 1985 May:12(5 Pt 1):816-21     [PubMed PMID: 4008685]


Vinson RP, Angeloni VL. Acquired digital fibrokeratoma. American family physician. 1995 Oct:52(5):1365-7     [PubMed PMID: 7572559]


Bart RS, Andrade R, Kopf AW, Leider M. Acquired digital fibrokeratomas. Archives of dermatology. 1968 Feb:97(2):120-9     [PubMed PMID: 5636043]


de Freitas PM, de Sb Xavier MH, Pereira GB, Rochael MC, de Oliveira Cortes JL, Quevedo LP, Araripe AA Jr. Acquired fibrokeratoma presenting as a giant pedunculated lesion on the heel. Dermatology online journal. 2008 Dec 15:14(12):10     [PubMed PMID: 19265623]

Level 3 (low-level) evidence


Choi JH, Jung SY, Chun JS, Seo JK, Lee D, Hwang SW, Sung HS. Giant acquired digital fibrokeratoma occurring on the left great toe. Annals of dermatology. 2011 Feb:23(1):64-6. doi: 10.5021/ad.2011.23.1.64. Epub 2011 Feb 28     [PubMed PMID: 21738365]

Level 3 (low-level) evidence


Verallo VV. Acquired digital fibrokeratomas. The British journal of dermatology. 1968 Nov:80(11):730-6     [PubMed PMID: 5696520]


Ali M, Mbah CA, Alwadiya A, Nur MM, Sunderamoorthy D. Giant fibrokeratoma, a rare soft tissue tumor presenting like an accessory digit, a case report and review of literature. International journal of surgery case reports. 2015:10():187-90. doi: 10.1016/j.ijscr.2015.03.041. Epub 2015 Mar 25     [PubMed PMID: 25863992]

Level 3 (low-level) evidence


Yu D, Morgan RF. Acquired digital fibrokeratoma: a case report. Annals of plastic surgery. 2015 Mar:74(3):304-5. doi: 10.1097/SAP.0b013e3182996ee6. Epub     [PubMed PMID: 24051460]

Level 3 (low-level) evidence


Altman DA, Griner JM, Faria DT. Acquired digital fibrokeratoma. Cutis. 1994 Aug:54(2):93-4     [PubMed PMID: 7956341]

Level 3 (low-level) evidence


Shih S, Khachemoune A. Acquired digital fibrokeratoma: review of its clinical and dermoscopic features and differential diagnosis. International journal of dermatology. 2019 Feb:58(2):151-158. doi: 10.1111/ijd.14046. Epub 2018 May 19     [PubMed PMID: 29777543]


Amarouch H, Aitourghoui M, Ramli I, Zaouri H, Senouci K, Hassam B. [Post-staphylococcal acquired digital fibrokeratoma: a new case]. Presse medicale (Paris, France : 1983). 2015 Jul-Aug:44(7-8):843-5. doi: 10.1016/j.lpm.2015.03.015. Epub 2015 Jun 3     [PubMed PMID: 26049914]

Level 3 (low-level) evidence


Sezer E, Bridges AG, Koseoglu D, Yuksek J. Acquired periungual fibrokeratoma developing after acute staphylococcal paronychia. European journal of dermatology : EJD. 2009 Nov-Dec:19(6):636-7. doi: 10.1684/ejd.2009.0771. Epub 2009 Jul 20     [PubMed PMID: 19620034]

Level 3 (low-level) evidence


Qiao J, Liu YH, Fang K. Acquired digital fibrokeratoma associated with ciclosporin treatment. Clinical and experimental dermatology. 2009 Mar:34(2):257-9. doi: 10.1111/j.1365-2230.2008.02808.x. Epub     [PubMed PMID: 19187308]

Level 3 (low-level) evidence


Nemeth AJ, Penneys NS. Factor XIIIa is expressed by fibroblasts in fibrovascular tumors. Journal of cutaneous pathology. 1989 Oct:16(5):266-71     [PubMed PMID: 2574200]


Pérez-Novo CA, Waeytens A, Claeys C, Cauwenberge PV, Bachert C. Staphylococcus aureus enterotoxin B regulates prostaglandin E2 synthesis, growth, and migration in nasal tissue fibroblasts. The Journal of infectious diseases. 2008 Apr 1:197(7):1036-43. doi: 10.1086/528989. Epub     [PubMed PMID: 18419541]


Lencastre A, Richert B. Flat-Pan Nail-Wide Acquired Epiungual Fibrokeratoma: Report of 4 Cases. Skin appendage disorders. 2019 Feb:5(2):111-113. doi: 10.1159/000491582. Epub 2018 Aug 29     [PubMed PMID: 30815446]

Level 3 (low-level) evidence


Rubegni P, Poggiali S, Lamberti A, Chiantini A, De Paola M, Peccianti C, Fimiani M. Dermoscopy of acquired digital fibrokeratoma. The Australasian journal of dermatology. 2012 Feb:53(1):47-8. doi: 10.1111/j.1440-0960.2011.00793.x. Epub 2011 Jul 12     [PubMed PMID: 22309331]

Level 3 (low-level) evidence


Hayashi K, Matori S, Kariya Y, Sonosaki T, Yamaguchi S, Hagiwara K, Uezato H, Takahashi K. Dermoscopic observation of acquired digital fibrokeratoma developed on the dorsum of the fourth left toe. The Journal of dermatology. 2016 Jan:43(1):107-8. doi: 10.1111/1346-8138.13152. Epub 2015 Oct 5     [PubMed PMID: 26434657]


Lee CY, Lee KY, Kim KH, Kim YH. Total excision of acquired periungual fibrokeratoma using bilateral proximal nail fold oblique incision for preserving nail matrix. Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.]. 2010:36(1):139-41. doi: 10.1111/j.1524-4725.2009.01368.x. Epub 2009 Nov 4     [PubMed PMID: 19889158]

Level 3 (low-level) evidence


Shelley WB, Phillips E. Recurring accessory "fingernail": periungual fibrokeratoma. Cutis. 1985 May:35(5):451-4     [PubMed PMID: 4006511]

Level 3 (low-level) evidence


Palaniappan V, Sadhasivamohan A, Sankarapandian J, Karthikeyan K. Acquired Fibrokeratoma: A Retrospective Study in a Tertiary Centre in South India. Indian journal of dermatology. 2022 May-Jun:67(3):312. doi: 10.4103/ijd.ijd_239_22. Epub     [PubMed PMID: 36386073]

Level 2 (mid-level) evidence


Patki AH, Mehta JM. Acquired digital fibrokeratoma in a patient with leprosy. Indian journal of leprosy. 1992 Apr-Jun:64(2):205-8     [PubMed PMID: 1607722]

Level 3 (low-level) evidence


Longhurst WD, Khachemoune A. An unknown mass: the differential diagnosis of digit tumors. International journal of dermatology. 2015 Nov:54(11):1214-25. doi: 10.1111/ijd.12980. Epub 2015 Jul 30     [PubMed PMID: 26235189]


Tyring SK. Human papillomavirus infections: epidemiology, pathogenesis, and host immune response. Journal of the American Academy of Dermatology. 2000 Jul:43(1 Pt 2):S18-26     [PubMed PMID: 10861103]


Bae JM, Kang H, Kim HO, Park YM. Differential diagnosis of plantar wart from corn, callus and healed wart with the aid of dermoscopy. The British journal of dermatology. 2009 Jan:160(1):220-2. doi: 10.1111/j.1365-2133.2008.08937.x. Epub 2008 Nov 28     [PubMed PMID: 19067694]

Level 3 (low-level) evidence


Forthman CL, Blazar PE. Nerve tumors of the hand and upper extremity. Hand clinics. 2004 Aug:20(3):233-42, v     [PubMed PMID: 15275682]


Pilavaki M, Chourmouzi D, Kiziridou A, Skordalaki A, Zarampoukas T, Drevelengas A. Imaging of peripheral nerve sheath tumors with pathologic correlation: pictorial review. European journal of radiology. 2004 Dec:52(3):229-39     [PubMed PMID: 15544900]


Fetsch JF, Laskin WB, Miettinen M. Superficial acral fibromyxoma: a clinicopathologic and immunohistochemical analysis of 37 cases of a distinctive soft tissue tumor with a predilection for the fingers and toes. Human pathology. 2001 Jul:32(7):704-14     [PubMed PMID: 11486169]

Level 3 (low-level) evidence


Cohen PR, Alpert RS, Calame A. Cellular Digital Fibroma: A Comprehensive Review of a CD34-Positive Acral Lesion of the Distal Fingers and Toes. Dermatology and therapy. 2020 Oct:10(5):949-966. doi: 10.1007/s13555-020-00418-3. Epub 2020 Jul 29     [PubMed PMID: 32728848]


Reddy IS, Somani VK. Giant periungual and subungual fibromas (Koenen's tumor) of tuberous sclerosis complex. Indian journal of dermatology, venereology and leprology. 2023 Jan-Mar:89(2):290-291. doi: 10.25259/IJDVL_1194_20. Epub     [PubMed PMID: 34114422]


Kint A, Baran R. Histopathologic study of Koenen tumors. Are they different from acquired digital fibrokeratoma? Journal of the American Academy of Dermatology. 1988 Feb:18(2 Pt 1):369-72     [PubMed PMID: 3346418]


Zaballos P, Carulla M, Ozdemir F, Zalaudek I, Bañuls J, Llambrich A, Puig S, Argenziano G, Malvehy J. Dermoscopy of pyogenic granuloma: a morphological study. The British journal of dermatology. 2010 Dec:163(6):1229-37. doi: 10.1111/j.1365-2133.2010.10040.x. Epub     [PubMed PMID: 20846306]