Keloid


Article Author:
Sarah McGinty


Article Editor:
Waqas Siddiqui


Editors In Chief:
Ritesh Menezes


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Frank Smeeks
Kristina Soman-Faulkner
Trevor Nezwek
Radia Jamil
Patrick Le
Sobhan Daneshfar
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
3/19/2019 6:57:40 PM

Introduction

Keloids result from abnormal wound healing in response to skin trauma or inflammation. Keloid development rests on genetic and environmental factors. Higher incidences are seen in darker skinned individuals of African, Asian, and Hispanic descent. Overactive fibroblasts producing high amounts of collagen and growth factors are implicated in the pathogenesis of keloids. As a result, classic histologic findings demonstrate large, abnormal, hyalinized bundles of collagen referred to as keloidal collagen and numerous fibroblasts. Keloids present clinically as firm, rubbery nodules in an area of prior injury to the skin. In contrast to normal or hypertrophic scars, keloidal tissue extends beyond the initial site of trauma. Patients may complain of pain, itching, or burning. Multiple treatment modalities exist although none are uniformly successful. The most common treatments include intralesional or topical steroids, cryotherapy, surgical excision, radiotherapy, and laser therapy.[1][2][3]

Etiology

Both genetic and environmental factors play a role in keloid development. Predisposed individuals may develop a keloid following any level of skin trauma including surgery, piercings, acne, tattooing, insect bites, burns, lacerations, abrasions, vaccinations, and any other process resulting in cutaneous inflammation. Increased tension in a wound also may contribute to keloid formation.[1][4][5]

Epidemiology

Dark-skinned individuals of African, Asian, and Hispanic descent have higher rates of keloid development compared to Caucasians. The incidence in these darker-pigmented populations ranges from 4.5% to 16%. The incidence is notably higher during pregnancy and puberty. A positive family history increases the risk for the development of keloids although no specific gene has been identified. Rare genetic syndromes can also confer increased risk for the development of keloids including Rubinstein-Taybi and Goeminne syndrome.[1]

Pathophysiology

Keloids are a result of aberrant wound healing. Standard wound healing consists of three phases: (1) inflammatory, (2) fibroblastic, and (3) maturation. In keloids, the fibroblastic phase continues, unchecked, resulting in the clinical and histopathological findings. 

Keloidal fibroblasts have increased proliferative activity, persist for longer, and have lower rates of apoptosis compared to typical wound healing. This results in an overproduction of collagen and cytokines.  Collagen synthesis in keloids is 20 times greater than that of healthy skin and three times greater than a hypertrophic scar.

Transforming growth factor-beta and platelet-derived growth factor are thought to be the primary drivers of this process. Transforming growth factor-beta, an integral part of wound healing, promotes chemotaxis of fibroblasts to the site of inflammation and produces collagen. Dysregulation of this pathway leads to fibrosis and abnormal scar response.[6][7][8]

Histopathology

The histologic hallmark of a keloid is increased whorls of thickened, hyalinized collagen bundles widely known as keloidal collagen. This feature is found in up to 55% of specimens. However, experts have determined the following four other diagnostic criteria when keloidal collagen is absent: 

  1. Standard epidermis and papillary dermis
  2. “Tongue-like” advancing edge below the papillary dermis
  3. Horizontal fibrous band in the upper reticular dermis
  4. Prominent fascia like a band in the deep dermis

Important clinical and histopathologic differential includes hypertrophic scar. An increased number of fibroblasts and thickened collagen bundles arranged parallel to the skin surface characterizes these lesions. Another common finding includes vertically oriented blood vessels, which are rare in keloids. Hypertrophic scars do not exhibit keloidal collagen. Contrary to previous belief, smooth muscle actin expression is not a reliable way to differentiate hypertrophic scar from keloid.

History and Physical

Keloids are benign, dermal growths related to previous skin trauma or inflammation. Lesions may develop as early as 1 to 3 months or as late as one year after injury. Spontaneous lesions have been reported. However, it is more likely that the injury was not recalled due to its insignificance or that the keloid development was delayed by months or even years. Keloids may develop anywhere, but the most commonly affected locations include deltoid, pre-sternal chest, upper back, and ear. Unusual locations for these growths include eyelids, genitalia, palms, and soles. Keloids present as firm, rubbery nodules and frequently project above the underlying skin. They may have a narrow base, resulting in pedunculated lesions, or develop into a more a broad-based plaque. As stated above, an important differential diagnosis includes hypertrophic scar which will not project above underlying skin further than 4 millimeters and, as a rule, will never extend beyond the initial area of injury. In contrast, keloids always extend beyond the area of original trauma. Color ranges from erythematous, flesh-colored, or hyperpigmented and may change with the evolution of the lesion. Although these lesions are benign, they are frequently symptomatic. In one study, 86% of patients complained of pruritus while 46% experienced pain. Other reported symptoms include tenderness and burning. Finally, keloids may have significant cosmetic implications for affected patients as they can grow to be large and disfiguring.[1][9]

Evaluation

Evaluation is primarily clinical. A biopsy is not required unless the diagnosis is in question. In that case, a biopsy is diagnostic. No further workup is necessary.

Treatment / Management

Keloids remain a therapeutic dilemma. Not only are they difficult to treat but incomplete therapy can lead to a keloid worsening and growing. Therefore, primary prevention is key. Predisposed individuals should avoid elective procedures if possible, especially ear piercing and tattooing. If accidental trauma occurs or surgical interventions are required, there are ways to minimize and perhaps prevent the development of keloid scar. Minimizing wound tension is important to reduce the risk for keloid development. Rapid primary closure and adequate hemostasis are the cited key elements in tension-free wound closure. Prolonged wound stabilization using silicone sheeting also may help reduce tension on wounds. Compression therapy is noted in the literature to reduce keloid development with pressures of 15 to 45 mmHg recommended for more than 23 hours per day for at least 6 months.

Several modalities alleviate symptoms of existing keloids:

  • Corticosteroids- Intralesional steroids are considered the first line in the treatment of keloid scars. Multiple injections at intervals of 4 to 6 weeks are required. Recommended doses range from 10 to 40 mg/cc of triamcinolone. This may be used alone or in combination with other modalities. Topical ointments and steroid impregnated tapes also have been shown to reduce symptoms of itching and burning. 
  • Cryotherapy- Delivery via spray, contact, or intralesional-needle cryoprobe all have been described. Multiple treatments are required. Freeze-thaw cycles of 10 to 20 seconds are recommended to achieve scar tissue necrosis. Post-treatment pigmentary alteration makes this method less desirable in darker skin types. 
  • Surgical excision- Due to high recurrence rate between 45% and 100%, this method should always be paired with an adjuvant therapy such as post-surgical radiation or intralesional steroid injections.  
  • Radiotherapy- Best utilized as adjuvant therapy 24 to 28 hours following excision. Caution should be used in patients less than 18 years of age and in vulnerable areas such as the head, neck, and breast as it carries an inherent risk of carcinogenesis.   
  • Laser- Successive sessions using 585 nanometers (nn) pulse-dye laser and 1065 nm neodymium-doped yttrium aluminum garnet (ndYAG) laser have been shown to induce flattening and regression of keloids. 
  • Other treatments including topical imiquimod following excision, intralesional botox, intralesional bleomycin, intralesional 5-fluorouracil, and silicone gel sheeting have also been reported to be successful in treating keloid scars either alone or in combination with the above modalities. 

It is important to manage patient expectations as all treatments require multiple sessions and do not uniformly result in complete regression of keloid. The most successful treatment results from the use of multiple modalities and tailoring therapy to meet patient needs.

Differential Diagnosis

When evaluating a patient with suspected keloids, the differential diagnosis is narrow. However, it is important to note key features to determine which lesions warrant skin biopsy. As discussed above, hypertrophic scars can appear very similar to keloids and occur after skin trauma. Hypertrophic scars tend to be smaller and, as a rule, are confined to the area of injury as opposed to keloids which can continue to grow and involve the surrounding skin. Dermatofibroma is another aberrant scar response that typically results in flesh-colored or hyperpigmented papule or nodule. The classic clinical feature of these lesions is central depression when applying lateral pressure, which is known as the “dimple sign.” Dermatofibrosarcoma protuberans is a rare, locally aggressive spindle cell tumor that arises on the trunk and proximal extremities of young adults. In contrast to keloids, these lesions have no preceding trauma and have more irregular borders. Keloidal variants include morphea and scleroderma. These patients would have progressive disease in the absence of a known inciting event and may also show other signs of connective tissue disease. Xanthoma disseminatum is rare, histiocytic proliferation with skin lesions that may resemble keloids. Lesions present acutely in a diffuse symmetric pattern, and systemic involvement may result in the development of diabetes insipidus. Finally, lobomycosis is a deep fungal infection caused by the organism Lacazia loboi. It presents as a slow-growing keloid-like nodule on distal extremities and is associated with exposure to dolphins or rural soil in Central and South America. 

Prognosis

Keloidal scars are benign, and treatment is primarily directed toward symptom relief or cosmetic concerns. 

Pearls and Other Issues

Keloids have a predilection for darker-skinned individuals. Keloids are a result of aberrant wound healing.  In contrast to hypertrophic scars, keloidal tissue extends beyond the area of initial skin injury. Treatment is difficult and rests primarily in symptom relief.

Enhancing Healthcare Team Outcomes

All physicians including nurse practitioners should be aware of keloids. Any healthcare provider doing surgery, administering injections or looking after trauma patients, must educate the patient on keloids. These skin lesions are extremely difficult to treat. Despite the wide number of treatment, none works consistently or reliably. Giving patients false hopes is another major problem when it comes to keloid treatment. Many of the treatments can in fact make the keloid scar look worse. If one has no idea what to do, the best advice is to leave the keloid alone.[10][11]


  • Image 284 Not availableImage 284 Not available
    Contributed by DermNetNZ
Attributed To: Contributed by DermNetNZ

Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Keloid - Questions

Take a quiz of the questions on this article.

Take Quiz
Which of the following refers to the overgrowth of tissue beyond the initial wound edges?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
What is the major difference between a keloid and a hypertrophic scar?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A patient complains of a dome-shaped linear scar that is wider than the original incision. What information would a patient be provided after a diagnosis of keloid is made?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following results from large quantities of collagen during scar formation?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A patient has total hip arthroplasty. The incision has healed but is raised, shiny, erythematous, and extends past the original incision. What is the diagnosis?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A 17-year-old female presents with a large keloid on her neck from a previous thyroid surgery. What is the best initial treatment?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is most highly associated with the development of a keloid scar?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following cell types is most associated with keloid formation?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is true regarding keloids? Select all that apply.



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Keloid - References

References

Abnormal wound healing: keloids., Robles DT,Berg D,, Clinics in dermatology, 2007 Jan-Feb     [PubMed]
Huang C,Liu L,You Z,Du Y,Ogawa R, Managing keloid scars: From radiation therapy to actual and potential drug deliveries. International wound journal. 2019 Mar 12;     [PubMed]
Wang M,Chen L,Huang W,Jin M,Wang Q,Gao Z,Jin Z, Improving the anti-keloid outcomes through liposomes loading paclitaxel-cholesterol complexes. International journal of nanomedicine. 2019;     [PubMed]
Palko JR,Arfeen S,Farooq AV,Reppa C,Harocopos GJ, Corneal keloid presenting forty years after penetrating injury: case report and literature review. Survey of ophthalmology. 2019 Mar 5;     [PubMed]
Kang S,Hur JK,Kim D, Advances in diagnostic methods for keloids and biomarker-targeted fluorescent probes. The Analyst. 2019 Mar 11;     [PubMed]
Chen Y,Chen Y,Liu Y, Abnormal Presentation of Aggressive Fibromatosis After Radiotherapy for Keloids: Case Report and Brief Literature Review. Annals of plastic surgery. 2018 Dec 13;     [PubMed]
Lei R,Shen J,Zhang S,Liu A,Chen X,Wang Y,Sun J,Dai S,Xu J, Inactivating the ubiquitin ligase Parkin suppresses cell proliferation and induces apoptosis in human keloids. Journal of cellular physiology. 2019 Feb 19;     [PubMed]
Coentro JQ,Pugliese E,Hanley G,Raghunath M,Zeugolis DI, Current and upcoming therapies to modulate skin scarring and fibrosis. Advanced drug delivery reviews. 2018 Aug 30;     [PubMed]
O'Boyle CP,Shayan-Arani H,Hamada MW, Intralesional cryotherapy for hypertrophic scars and keloids: a review. Scars, burns     [PubMed]
Lee YI,Kim J,Yang CE,Hong JW,Lee WJ,Lee JH, Combined Therapeutic Strategies for Keloid Treatment. Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.]. 2019 Jan 11;     [PubMed]
Greywal T,Krakowski AC, Pediatric dermatology procedures and pearls: Multimodal revision of earlobe keloids. Pediatric dermatology. 2018 Mar;     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Pathology-Forensics. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Pathology-Forensics, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Pathology-Forensics, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Pathology-Forensics. When it is time for the Pathology-Forensics board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Pathology-Forensics.