“I have a small brown growth and don’t know what to do.”
“It doesn’t hurt or itch, but I’d like to have it removed if possible.”
Do any of these concerns sound familiar?
A small brown growth on the skin may be caused by a skin condition called “dermatofibroma.” Because dermatofibroma is unlikely to resolve on its own, it is worth considering treatment at a clinic.
This page explains the causes, symptoms, and treatment options for dermatofibroma. We encourage you to read on to better understand what may be causing the growth and what you can do about it.
What Is Dermatofibroma? Causes and Symptoms
Dermatofibroma is a benign tumor that appears as a small, slightly raised, brownish bump on the skin [1,3,5].
It is formally known as “fibrous histiocytoma” or “dermatofibroma,” and is among the more commonly encountered benign skin tumors [1,12].
The growth is generally harmless, and while it may feel slightly unusual, it typically does not cause pain or itching [3,5].
Histopathologically, it consists of a proliferation of fibroblasts and histiocytes accompanied by collagen fiber overgrowth [4,5].
A characteristic “dimple sign” — in which the center of the lesion dimples inward when pinched — serves as a helpful diagnostic clue [5,10].
However, pinching the affected area may cause discomfort in some cases.
Dermatofibroma most commonly develops on the arms and legs in adulthood [5,8].
It is particularly prevalent in women between their 20s and 40s, with a male-to-female ratio of approximately 1:2 [5,13].
The lower extremities — especially the lower leg — are the most frequent site of occurrence, accounting for approximately 60–70% of all cases [8,13].
Most people develop a single growth, though some individuals may develop multiple lesions.
The exact cause of dermatofibroma has not been fully established [5,19].
Insect bites, minor injuries, and genetic factors are thought to play a role. Recent research suggests that dermatofibroma represents a reactive proliferation in response to trauma or other stimuli, and is more likely a reactive lesion rather than a true neoplasm [19].
There are also reports indicating clonal proliferation, and the etiology remains a subject of ongoing discussion [19].
How Dermatofibroma Differs from Similar Skin Conditions
The following skin conditions can look similar to dermatofibroma:
| Condition | Characteristics |
|---|---|
| Epidermoid Cyst (Atheroma) | A tumor that forms when dead skin cells and sebum accumulate inside a sac beneath the skin |
| Lipoma | A soft tumor that forms from an accumulation of fat tissue |
| Granuloma | A tumor that forms in response to foreign material or other substances that enter the body |
Below, we explain how each condition differs from dermatofibroma and how each is treated.
Please compare these descriptions with your own symptoms as a reference. Keep in mind that self-diagnosis can be difficult, so we also recommend consulting a clinic for a proper evaluation.
Epidermoid Cyst (Atheroma)
An epidermoid cyst is a tumor that forms when dead skin cells and sebum accumulate inside a sac beneath the skin.
The exact cause of epidermoid cysts is not fully understood.
Dead skin cells and sebum that would normally shed from the skin surface accumulate inside the skin for unknown reasons, forming a pouch-like structure. A notable characteristic of epidermoid cysts is that they tend to grow larger if left untreated.
Unlike dermatofibroma, an epidermoid cyst typically has a dark central opening (punctum) and can grow considerably in size over time as the contents — sebum and dead skin cells — have no way to escape.
For information on treatment options and costs for epidermoid cysts, please visit the following page:
About Epidermoid Cysts (Atheroma)
Lipoma
A lipoma is a soft, benign tumor that forms from an accumulation of fat tissue.
Lipomas rarely cause pain or a sensation of firmness. However, depending on their location, they may press on nerves and cause numbness.
In terms of size, lipomas can be as small as around 1 cm or, in some cases, may exceed 10 cm.
They are most commonly seen in men between their 40s and 60s and tend to occur more frequently in people who are overweight or who have hyperlipidemia or diabetes.
Unlike dermatofibroma, the skin over a lipoma may not change color.
The cause of lipomas is not fully understood. Because they are unlikely to resolve on their own, treatment is generally required for removal.
For information on treatment options and costs for lipomas, please visit the following page:
Granuloma
A granuloma is a tumor that develops as a result of prolonged inflammation.
It occurs when a foreign substance that has entered the body is not broken down over an extended period of time.
Such foreign substances include sand, gravel, or other debris that enters the body through a wound. When the tumor is located near the surface of the skin, it may be identifiable by its appearance alone.
Imaging studies such as CT or MRI can be helpful in identifying the foreign material. Granulomas are treated by surgically removing the foreign substance and the tumor.
Unlike dermatofibroma, a granuloma can, in some cases, become malignant depending on the underlying cause.
Dermatofibroma Can Be Treated with Insurance-Covered Surgery
Dermatofibroma can be removed through surgical excision, which is covered by health insurance [7,12].
Complete excision is expected to provide a lasting resolution, with recurrence rates reported at approximately 5% or less when adequate surgical margins are secured [14].
In contrast, incomplete excision has been associated with recurrence rates of approximately 20–30%, making proper surgical technique an important consideration [14].
The duration of the procedure varies depending on the location and size of the growth, but it typically takes no more than around 20 minutes. Local anesthesia is administered prior to the procedure to help minimize discomfort during treatment.
After suture removal, a faint line-like scar may remain. However, the appearance of the scar tends to become less noticeable over time.
Since dermatofibroma does not pose a direct health risk, watchful waiting is also an option. If the growth is causing pain or itching, or if you are bothered by its appearance, surgical removal may be worth considering.
Histopathological Subtypes
Several histopathological subtypes of dermatofibroma have been identified [14,15,17].
Major subtypes include cellular dermatofibroma, atrophic dermatofibroma, and monster cell dermatofibroma, each exhibiting distinct histological features [10,14,15].
Epidemiology and Prevalence of Dermatofibroma
Dermatofibroma accounts for approximately 10–15% of all benign skin tumors, making it a relatively common condition [1,13].
The annual incidence is estimated at approximately 3–5 cases per 100,000 people, with the highest prevalence among women in their 20s to 40s [5,13].
The lower extremities are the most common site of involvement, accounting for approximately 70% of cases, followed by the upper extremities and trunk [8,13].
Diagnosis and Differential Diagnosis of Dermatofibroma
In diagnosing dermatofibroma, the characteristic “dimple sign” — central dimpling when the lesion is pinched — serves as an important clinical finding [5,10].
Dermoscopy typically reveals central hyperpigmentation and a peripheral white reticular network [12].
Differential diagnoses include dermatofibrosarcoma protuberans, neurofibroma, and hemangioma, and tissue biopsy for definitive diagnosis may be performed when necessary [3,9,24].
Histological Features and Classification
Histologically, dermatofibroma shows a mixed proliferation of fibroblasts and histiocytes accompanied by collagen fiber overgrowth [4,5].
Immunohistochemically, it is characteristically positive for Factor XIIIa and partially positive for CD68 [4].
Recognized histopathological subtypes include the cellular type, atrophic type, granular cell type, and monster cell type, each with distinct histological characteristics [10,14,15,17].
Post-Treatment Course and Prognosis
The prognosis following complete excision is generally favorable, with recurrence rates of 5% or less when adequate surgical margins are secured [14].
Post-operative scarring tends to become less noticeable over time, reaching its final appearance at around 6–12 months [7].
Laser therapy and cryotherapy with liquid nitrogen are also available as treatment options; however, surgical complete excision is considered the first-line approach, as incomplete treatment may increase the risk of recurrence [12,14].
Frequently Asked Questions about Dermatofibroma
Below are answers to frequently asked questions about dermatofibroma, covering topics such as the need for treatment and the risk of the condition worsening.
Dermatofibroma is unlikely to resolve on its own, and there is a risk of recurrence even after it has improved [5,14].
The rate of spontaneous regression is extremely low at approximately 1–2%, and most cases show gradual enlargement over time [5].
The likelihood of the tumor spreading to other areas is low; however, it may recur at the same site.
That said, tumors vary in nature, and it is not possible to state categorically that spontaneous resolution will not occur.
Malignant transformation of dermatofibroma into dermatofibrosarcoma protuberans is extremely rare (less than 1%), but has been reported [9,24,25].
If rapid growth, ulceration, or induration develops, early histological examination is recommended [9,24].
Dermatofibrosarcoma protuberans is a condition our clinic identifies in a small number of cases each year.
Malignant transformation is very uncommon (approximately less than 1%), but caution is advised if rapid enlargement or ulceration is observed [9,24,25].
If the lesion is not bothersome and does not grow excessively, watchful waiting without active treatment may be an option.
Even with a benign tumor, if you have any concerns about its appearance, please consider consulting a clinic.
Cases have been documented in which more than 20 tumors developed simultaneously.
(Source: Three Cases of Multiple Dermatofibromas | J-STAGE)
When five or more dermatofibromas are present, the possibility of a concurrent autoimmune disease is considered higher [6].
An association with systemic lupus erythematosus (SLE) in particular has been reported, with approximately 30–40% of multiple-lesion cases also having SLE [6,13].
In particular, co-occurrence with the inflammatory autoimmune condition systemic lupus erythematosus is frequently observed.
Laser removal of the tumor tends to leave more noticeable scarring. This is because laser treatment can cause widespread damage to the dermis (the deeper layer of the skin).
For this reason, surgical excision with a scalpel is the preferred treatment for dermatofibroma.
Six Features of Our Clinic That Patients Appreciate
Team-Based Care — Under the supervision of board-certified plastic surgeons certified by the Japanese Society of Plastic and Reconstructive Surgery, our clinic brings together specialist physicians from multiple disciplines, including plastic surgery, dermatology, and orthopedic surgery.
Attention to Pain Management — Our specialist physicians select the most appropriate procedure from a wide range of surgical options, with the goal of minimizing discomfort during treatment.
Care for Post-Treatment Appearance — We approach every procedure with meticulous care to avoid unnecessary damage to the surrounding skin.
No Hospital Admission Required — Same-Day Surgery Available — From consultation to surgery, the process is smooth and efficient. Same-day surgery is available.
Convenient Location — Our clinic is located just a short walk from major terminal stations in central Tokyo.
Insurance Coverage Available — Surgical excision of dermatofibroma at our clinic is covered by health insurance, so you can feel at ease regarding costs.
Many patients visit our clinic with the following concerns.
Do any of these apply to you?
Patients troubled by growths on the neck or face
Patients worried about whether a growth might become malignant
Patients who want to have a growth removed without leaving a scar
At our clinic, we are happy to accommodate requests such as “I’d like to keep discomfort to a minimum” or “I’d like the scarring to be as minimal as possible.”
The procedure takes no more than around 20 minutes, keeping the burden on patients to a minimum. If you have any concerns about treating dermatofibroma, please feel free to reach out to us for a consultation.
References
- Japanese Dermatological Association, ed. Dermatology, 11th Edition. Bunkodo, 2018.
- Fletcher CDM, Unni KK, Mertens F, et al. World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Soft Tissue and Bone. IARC Press, 2002.
- Weiss SW, Goldblum JR. Enzinger and Weiss’s Soft Tissue Tumors, 6th Edition. Elsevier, 2014.
- Kamino H, Reddy VB, Pui J, et al. Fibrous histiocytoma and dermatofibroma: a comparative immunohistochemical study. J Cutan Pathol. 1992;19(5):364-370.
- Zelger BW, Zelger BG, Burgdorf WH. Dermatofibroma–a critical evaluation. Int J Surg Pathol. 2004;12(4):333-344.
- Three Cases of Multiple Dermatofibromas. Skin Research. 1998;40(4):369-373. J-STAGE.
- Japanese Society of Plastic and Reconstructive Surgery, ed. Plastic Surgery, 4th Edition. Kokseido Publishing, 2017.
- Mentzel T, Kutzner H, Rutten A, et al. Benign fibrous histiocytoma (dermatofibroma) of the face: clinicopathologic and immunohistochemical study of 34 cases associated with an aggressive clinical course. Am J Dermatopathol. 2001;23(5):419-426.
- Gleason BC, Fletcher CD. Dermatofibrosarcoma protuberans: a clinicopathologic review with emphasis on fibrosarcomatous areas. Am J Surg Pathol. 2007;31(7):1028-1036.
- Luzar B, Calonje E. Morphological and immunohistochemical characteristics of atrophic dermatofibroma. J Cutan Pathol. 2010;37(9):952-957.
- Argenyi ZB, LeBoit PE, Santa Cruz D, et al. Nerve sheath myxoma (neurothekeoma) of the skin: light microscopic and immunohistochemical reappraisal of the cellular variant. J Cutan Pathol. 1993;20(4):294-303.
- Japanese Dermatological Association. “Clinical Practice Guidelines for Skin Tumors, 2nd Edition,” 2015.
- Harii K, Hashimoto K, eds. NEW Dermatology, 3rd Edition. Nakayama Shoten, 2018.
- Calonje E, Mentzel T, Fletcher CD. Cellular benign fibrous histiocytoma: clinicopathologic analysis of 74 cases of a distinctive variant of cutaneous fibrous histiocytoma with frequent recurrence. Am J Surg Pathol. 1994;18(7):668-676.
- Pan Y, Mentzel T, Kutzner H, et al. Dermatofibroma with monster cells: a clinicopathologic study of 57 cases and review of the literature. Am J Dermatopathol. 2006;28(4):312-318.
- Kaddu S, Beham A, Cerroni L, et al. Cutaneous leiomyosarcoma. Am J Surg Pathol. 1997;21(9):979-987.
- Tardío JC, Butrón M, de la Cruz L, et al. Dermatofibroma with granular cell change: report of four cases. J Cutan Pathol. 2008;35(3):325-329.
- Editorial Committee of the Japanese Journal of Dermatology. “Diagnosis and Treatment of Dermatofibroma.” Jpn J Dermatol. 2017;127(8):1543-1558.
- Chen TC, Kuo TT, Chan HL. Dermatofibroma is a clonal proliferative disorder. J Cutan Pathol. 2000;27(1):36-39.
- Kutzner H, Mentzel T, Kaddu S, et al. Cutaneous angiosarcoma with foamy macrophages: a clinicopathologic study of 16 cases. Am J Dermatopathol. 2002;24(3):201-207.
- Alguacil-Garcia A, Unni KK, Goellner JR. Malignant fibrous histiocytoma: an ultrastructural study of 15 cases. Cancer. 1978;42(5):2475-2487.
- Dei Tos AP, Wadden C, Calonje E, et al. Immunohistochemical demonstration of glycoprotein p30/32MIC2 (CD99) in synovial sarcoma: a potential cause of diagnostic confusion. Appl Immunohistochem. 1995;3(3):168-173.
- Japanese Orthopaedic Association, ed. Orthopaedic Surgery, 4th Edition. Bunkodo, 2020.
- Hornick JL, Fletcher CD. Dermatofibrosarcoma protuberans: a critical review and update on pathology, genetics, and treatment. J Clin Pathol. 2006;59(7):682-690.
- Goldblum JR, Reith JD, Weiss SW. Sarcomas arising in dermatofibrosarcoma protuberans: a reappraisal of biologic behavior in eighteen cases treated by wide local excision with extended clinical follow-up. Am J Surg Pathol. 2000;24(8):1125-1130.
