Abnormal repair: chronic wounds, hypertrophic scar, keloid, contracture !

Lesion

Repair can fail in three ways: too little (a wound that will not close), too much (a raised scar or keloid), or a scar that shrinks and pulls.

Updated 2026-11-01

What it is

Repair goes wrong when it is deficient, excessive or produces contracture. Deficient repair gives dehiscence and chronic ulcers (venous, arterial, pressure, diabetic). Excessive repair gives exuberant granulation tissue, hypertrophic scars and keloids, and aggressive fibroblast proliferations (fibromatoses). Contracture, excessive shrinking by myofibroblasts, deforms and limits movement after burns. The keloid versus hypertrophic scar comparison is a classic exam question.

Structure

Chronic ulcer: base of granulation tissue and fibrin, a thickened edge of epidermis that does not advance, fibrotic surroundings.
Exuberant granulation tissue: red, friable tissue protruding above the level of the skin.
Fibromatosis (such as palmar fibromatosis or desmoid tumour): infiltrating bundles of bland fibroblasts and myofibroblasts; locally aggressive, does not metastasise.
Contracture: a short, thick band of scar across a joint or the palm that limits extension.

Hypertrophic scar vs keloid

Feature	Hypertrophic scar	Keloid
Borders	Stays within the original wound	Grows beyond the wound into normal skin
Course	Appears within weeks; often flattens and regresses over months	Can appear months later; does not regress
After excision	Recurrence uncommon	Recurrence frequent
Typical sites	Anywhere, especially over joints and after burns	Earlobes, chest, shoulders, upper back
Who	Any skin type	More frequent in people of African, Asian and Hispanic descent; often familial; usually under 30
Histology	Collagen nodules parallel to the surface, with myofibroblasts	Thick, glassy (hyalinised) collagen bundles in disarray

Clinical notes

Burns of the palms, soles and front of the chest, and burns across joints, are especially prone to contracture.
Keloids are treated with steroid injections, pressure, silicone, cryotherapy, laser or radiation; surgery alone can make them come back larger.
A chronic wound that changes appearance is biopsied, because squamous cell carcinoma can arise in long-standing scars and ulcers.

Test yourself

Think of the answer, then tap the question to see it.

How is a keloid told apart from a hypertrophic scar clinically?

A keloid extends beyond the original wound and does not regress; a hypertrophic scar stays within the wound edges and often flattens over months.

Which cell causes scar contracture?

The myofibroblast, a fibroblast with contractile alpha-smooth muscle actin.

What is a Marjolin ulcer?

A squamous cell carcinoma arising in a chronic wound or an old burn scar.

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Elsewhere in DurgiPedia

← All of general pathology

Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: Keloids: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Venous Leg Ulcer (StatPearls (NCBI Bookshelf), 2024); Pressure Sores | Bedsores | Pressure Ulcers | MedlinePlus (MedlinePlus, US National Library of Medicine, 2026).

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Representative model, for educational purposes only.