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External ear tumors - benign / nonneoplastic

Keloid

Authors: Andrew Dettrick, M.B.B.S., Ruta Gupta, M.D.

Editorial Board Member: Bin Xu, M.D., Ph.D.

Deputy Editor-in-Chief: Kelly Magliocca, D.D.S., M.P.H.

Last author update: 22 May 2023

Last staff update: 22 May 2023

Copyright: 2002-2024, PathologyOutlines.com, Inc.

PubMed Search: Keloid

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Table of Contents

Cite this page: Dettrick A, Gupta R. Keloid. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/earkeloid.html. Accessed April 26th, 2024.

Definition / general

Abnormal proliferation of scar tissue that extends beyond the boundaries of the initial injury and does not regress (Sci Rep 2021;11:9390)
Forms at the site of cutaneous injury (often minor) (Sci Rep 2021;11:9390)

Essential features

Excessive scar tissue that extends beyond the boundaries of the initial injury
Very common in dark skinned people (Fitzpatrick skin types 4 - 6) (Cureus 2022;14:e23503)
Recurrence after excision is common (Burns Trauma 2020;8:tkaa031)
Characteristic broad, pink bands of collagen (keloidal collagen)

Terminology

Keloid / keloid scar
Keloid is Greek for crab claw
Not to be confused with hypertrophic scar, which is confined to the limits of the injury (Exp Dermatol 2021;30:146)

ICD coding

ICD-10: L91.0 - hypertrophic scar
ICD-11: EE60.0 - keloid

Epidemiology

Any age but most are in patients 10 - 30 years old (Front Cell Dev Biol 2020;8:360)
15 times more common in Asian, Hispanic and African populations (J Clin Aesthet Dermatol 2021;14:S24)
Among keloids in the head and neck, 70% occur on the ear / earlobe (Facial Plast Surg Aesthet Med 2021;23:59)
Common in young African women after ear piercing
Unique to humans (Adv Wound Care (New Rochelle) 2019;8:77)
First recorded in the Smith papyrus from Egypt around 1700 B.C. (Exp Dermatol 2021;30:146)

Sites

Sites of previous surgery, trauma or burns
Common sites: anterior chest, shoulders, upper back, back of neck, cheeks and earlobes (Clujul Med 2013;86:313)

Pathophysiology

Exact pathogenesis of keloids and hypertrophic scar formation is unknown
Keloids and hypertrophic scars are an abnormal response to trauma
Wounds more likely to undergo keloid formation include wounds healing by secondary intention, wounds with prolonged inflammation (foreign body, infection, burn, earring site) and sites of repeated trauma (Clujul Med 2013;86:313)
Hypothesized pathogenesis involves excessive and prolonged inflammation leading to dysregulated normal healing with excessive production of collagen, elastin and extracellular matrix (Scars Burn Heal 2021;7:2059513120980320)
Fibroblasts and mast cells are increased (Scars Burn Heal 2021;7:2059513120980320)
Growth factors and cytokines such as TGF beta, TNF alpha, interleukins are increased in keloids (Scars Burn Heal 2021;7:2059513120980320)
Keloids have higher collagenase activity, type III collagen, chondroitin 4 sulphate and glycosaminoglycans than normal scars (Exp Dermatol 2021;30:146)
Inconsistent genetic associations have been found linked to certain HLA subtypes and blood group A (Téot: Textbook on Scar Management, 1st Edition, 2020)

Etiology

May develop after minor injuries, trauma, burns, insect bites, surgery, cryotherapy, topical treatments (e.g., imiquimod), acne, infections (e.g., shingles) and immunization (Int J Mol Sci 2017;18:606)
May arise months or years after injury (Am Fam Physician 2009;80:253)

Clinical features

Patients usually present with cosmetic concerns but may present with itch or pain (J Clin Aesthet Dermatol 2021;14:S24)
Red to purple, firm, smooth and raised area with no hair
Grows slowly, over months to years
Characteristically grow laterally beyond the border of the original wound (Burns Trauma 2019;7:39)
Clinical overlap can make distinction from hypertrophic scars and other mimics difficult (Exp Dermatol 2021;30:146)
Risk factors include
- Age: < 30
- Fitzpatrick skin types 4 - 6 (Cureus 2022;14:e23503)
- Body region (see Sites) (Facial Plast Surg Aesthet Med 2021;23:59)
- Family history
- Previous history or multiple keloids
- History of only minor injury preceding onset of the scar
- Local tension on the skin
- Pregnancy
- Hypertension
- Rare syndromes (e.g., Noonan syndrome)
No useful biomarkers exist to predict risk

Diagnosis

Can usually be diagnosed by visual inspection, palpation and history (Burns Trauma 2019;7:39)
May mimic a tumor and therefore imaging (ultrasound, CT or MRI) may help define extent and nature but there are no imaging modalities that can accurately identify keloids (Burns Trauma 2019;7:39)
Ultrasound elastography may be helpful as keloids and hypertrophic scars are harder than the surrounding tissues
Ultrasound may also assess effect of treatment

Radiology description

Ultrasound: hypoechoic dermal based lesion

Radiology images

Images hosted on other servers:

Keloid ultrasound appearance

Prognostic factors

Keloid is biologically harmless with no risk of malignant transformation (Sci Rep 2021;11:9390)
Most eventually stop growing and remain stable or even involute slightly (J Plast Reconstr Aesthet Surg 2014;67:87)
Persistence and recurrence are common (Semin Plast Surg 2021;35:145)
May lead to aesthetic issues and serious adverse psychosocial outcomes (G Ital Dermatol Venereol 2019;154:148)
May undergo suppuration, in which cystic cavities in keloids result in acute inflammatory flares and oozing (Int J Dermatol 2021;60:1392)

Case reports

10 year old child with meatoplasty keloid (J Laryngol Otol 2006;120:594)
30 year old woman with keloids in stretch marks (Clin Case Rep 2022;10:e6723)
32 year old man developed keloids following cupping therapy (Plast Reconstr Surg Glob Open 2022;10:e4669)
47 year old woman with extensive keloid scarring from pemphigus vulgaris (Clin Case Rep 2022;10:e6424)
70 year old woman with spontaneous keloids (Cureus 2022;14:e23227)

Treatment

Multiple treatment options exist and there is considerable variability in practice
Optimal treatment will vary depending on the age of the patient (pediatric versus adult) and body site
An escalating treatment algorithm may be followed (Burns Trauma 2019;7:39)
Treatment options include
- Emollients and regular massage
- Occlusive dressing
- Compression
- Fixation for lesions on a joint
- Local corticosteroid
  - Steroid tape / plaster
  - Steroid injections: intralesional steroids (e.g., triamcinolone acetonide)
- Surgical excision
  - Recurrence following excision alone 45 - 100%; the new keloid may be larger than the original (Burns Trauma 2020;8:tkaa031)
  - Excision may be combined with other modalities including steroids, imiquimod, bleomycin, cryotherapy or radiotherapy and recurrence rates are lower (Dermatol Ther 2022;35:e15425)
- Radiotherapy (Front Med (Lausanne) 2022;9:1043840)
- Laser therapy is not effective as recurrence rates are very high
- Other injectables: 5FU, interferon
- Oral medicines if large or multiple keloids

Clinical images

Images hosted on other servers:

Keloids and hypertrophic scars

Gross description

Polypoid, covered by thin, hairless skin
Can be small (< 2 cm) up to very large

Gross images

Contributed by Andrew Dettrick, M.B.B.S. and Ruta Gupta, M.D.

Raised dome with hairless surface

Cut surface

Microscopic (histologic) description

Lesion of the deep dermis; sparing of papillary dermis (Am J Dermatopathol 2004;26:379)
Characteristic long, broad, closely packed collagen bundles that stain uniformly eosinophilic (keloidal collagen) arranged in haphazard fascicles (Scars Burn Heal 2021;7:2059513120980320)
Fibroblasts are increased compared to normal skin (Front Cell Dev Biol 2020;8:360)
May appear edematous due to increased dermal mucosubstances (J Zhejiang Univ Sci B 2022;23:699)
Tongue-like advancing edge (Front Cell Dev Biol 2020;8:360)
Epidermis may be normal, thin or thick (most) and may be affected by secondary changes (such as hypertrophy and inflammation due to irritation / scratching) (Front Cell Dev Biol 2020;8:360)
Lesion replaces adnexal structures (i.e., hair follicles and sweat glands) (Histol Histopathol 2015;30:1033)
Fewer capillaries and blood vessels than surrounding skin (J Plast Surg Hand Surg 2010;44:272)
Tend to have marked inflammation in the dermis at the leading edge of growing keloids (Scars Burn Heal 2021;7:2059513120980320)
Overlap with hypertrophic scar and therefore correlation with the clinical features is recommended

Microscopic (histologic) images

Contributed by Andrew Dettrick, M.B.B.S.

Dermal lesion

Edge of lesion

Keloidal collagen

Increased fibroblasts

Virtual slides

Images hosted on other servers:

Polypoid shape

Increased fibroblasts

Characteristic keloidal collagen

Videos

Keloid scar:
5 minute pathology pearls
by Dr. Jerad Gardner

Sample pathology report

Skin sternum, excision:
- Dermal scar with keloidal type collagen (see comment)
- Comment: The histological features are consistent with keloid or hypertrophic scar; correlation with the clinical features is recommended.

Differential diagnosis

Hypertrophic scar:
- Confined to the area of injury without lateral extension
- Histological overlap: tends to have more delicate fibrillar collagen and no abundant mucosubstances
- Does not recur; clinical correlation may be required to help distinction from keloid
Dermatofibroma, particularly keloidal dermatofibroma:
- More cellular; typically lacks keloidal collagen
- No history of preceding trauma
Dermatofibrosarcoma protuberans:
- No history of preceding incisions / surgery at the site
- Pseudoepitheliomatous hyperplasia of the overlying epidermis
- Storiform pattern
- More cellular
- Cytological atypia present but may be subtle
- Lacks keloidal collagen
- Infiltrative edges
- Extension into subcutaneous tissue
Morphea / scleroderma:
- Involves full thickness of dermis
- Architecture of dermis largely intact
- Collagen is thickened and hypereosinophilic but does not form intersecting bands
- Perivascular inflammatory infiltrate of lymphocytes, plasma cells and macrophages in early lesions
- Does not have increased ground substance
Desmoplastic melanoma:
- Poorly circumscribed with deep infiltration
- Elongated spindle cells surrounded by collagen bundles; also scattered hyperchromatic or multinucleated cells with bizarre nuclei
- May have small foci of lymphoid aggregates
- May be pure or combined with classic melanoma

Additional references

eMedicine: Keloids [Accessed 1 February 2023], DermNet: Keloid and Hypertrophic Scar [Accessed 2 February 2023]

Board review style question #1

Which of the following is true of keloid?

Hypertrophic scar is synonymous with keloid scar
Keloids are more common in Asian and African populations
Recurrence after surgical excision is uncommon
Thick collagen bundles are unique to keloid

Board review style answer #1

B. Keloids are more common in Asian and African populations. Keloids are up to 15 times more common in Asians, Hispanics and Africans. Answer A is incorrect because hypertrophic scars overlap histologically with keloid but are a separate clinical entity; clinical correlation may be required to separate them. Answer C is incorrect because recurrence occurs in up to half following simple excision. Answer D is incorrect because keloidal collagen is characteristic of keloid but can be seen to a lesser extent in hypertrophic scars.

Comment Here

Reference: Keloid

Board review style question #2

This is a photomicrograph of an excision biopsy from the earlobe of a 22 year old Japanese-Australian woman. What is your diagnosis?

Dermatofibroma
Hypertrophic scar
Keloid
Scleroderma / morphea

Board review style answer #2

C. Keloid. The image shows the classic and characteristic appearance of keloidal collagen. Answer A is incorrect because while dermatofibroma can be similar in appearance, it is typically more cellular and is most common on the legs. Answer B is incorrect because while hypertrophic scars can overlap in histological appearance with keloid, they are generally more cellular and have less keloidal collagen. Clinical history helps to make the diagnosis as Asian individuals have a much higher risk, keloids are most common in young people (10 - 30 years old) and the earlobe is a typical site. Answer D is incorrect because while scleroderma / morphea can mimic keloid on a small biopsy, the collagen pattern is different (being more ordered and almost acellular) and the clinical history is not suggestive.

Comment Here

Reference: Keloid

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