Scarring Alopecia

Scarring alopecia is hair loss caused by the permanent destruction of the hair follicle, which is replaced by scar tissue (fibrotic tissue), and whose function is not restored. It is a type of localized alopecia, meaning it affects only a specific area of the scalp.

The causes of scarring alopecia are mainly twofold, and it is therefore classified into the following types:

• Primary scarring alopecia: the hair follicle is destroyed due to an inflammatory, infectious, or autoimmune disease affecting the scalp.
• Secondary scarring alopecia: it occurs due to external causes such as trauma, burns, or surgery.

Hair loss resulting from scarring alopecia is permanent; therefore, lost hair cannot be recovered. Treatments are thus focused on addressing the underlying cause and halting the progression of baldness.

Symptoms

The most characteristic symptoms of scarring alopecia are:

• Well-defined bald patches.
• Scalp inflammation.
• Erythema.
• Increased sensitivity.
• Itching in hair-loss areas.
• Scars, crusts, or pustules.
• In some types, one of the first signs is hair thinning and breakage.

Causes

There are three main types of scarring alopecia depending on their origin:

• Primary scarring alopecia: white blood cells of the immune system play a key role in disease development.
  • Lymphocytic alopecia: lymphocytes (white blood cells) destroy hair follicles.
    • Lichen planopilaris: one of the most common forms. It causes erythema and scaling of the skin around follicles and is often pruritic.
    • Frontal fibrosing alopecia: hair loss occurs along the hairline, creating a "headband-like" pattern. It is common in postmenopausal women.
    • Discoid lupus erythematosus: produces scaly plaques with central atrophy.
  • Neutrophilic alopecia: due to acute inflammation, neutrophils (the most abundant white blood cells) infiltrate the follicle, leading to its destruction.
    • Folliculitis decalvans: often associated with Staphylococcus aureus infection; it causes pustules and crusts leading to patchy hair loss.
    • Dissecting cellulitis: also known as Hoffmann disease; a painful form of alopecia characterized by inflammatory nodules that form purulent fistulas.
  • Mixed alopecia: both lymphocytes and neutrophils are involved.
    • Central centrifugal scarring alopecia: begins with destruction of hair follicles at the crown and spreads outward in a centrifugal pattern. It causes inflammation, pain, and itching.
• Secondary scarring alopecia: usually localized to a specific area of the scalp. Main causes include:
  • Trauma: wounds, lacerations, avulsions (injuries in which tissue is partially or completely torn away).
  • Thermal or chemical burns.
  • Infections such as tinea capitis.
  • Radiotherapy applied to the scalp.
  • Surgical procedures: hair loss occurs at incision scar sites.
  • Trichotillomania: a psychiatric disorder characterized by the compulsive urge to pull out scalp hair, eyebrows, or eyelashes.

Risk factors

The risk of scarring alopecia is higher in the following situations:

• Advanced age.
• Genetic predisposition.
• Trauma or scalp injuries.
• Any of the conditions associated with this type of hair loss, whether physical or psychiatric.
• Medical treatments that may lead to follicular scarring, such as surgery or cranial radiotherapy.
• Frontal fibrosing alopecia is more common in postmenopausal women.
• Central centrifugal scarring alopecia is more prevalent in middle-aged Black women.

Complications

The most frequent complications of scarring alopecia are:

• Spread of inflammation leading to enlargement of hairless areas.
• Depression.
• Low self-esteem.
• Anxiety.
• Social isolation.
• Bacterial infections: inflammation or scratching may facilitate entry of viruses or bacteria.
• Formation of visible scars.
• Scalp skin thinning.
• Increased sensitivity and burning sensation in the affected area.

Prevention

Scarring alopecia cannot be prevented in most cases; however, some types may be controlled by following these recommendations:

• To limit traction-related hair loss, avoid:
  • Frequently tight hairstyles (braids, ponytails).
• To care for the scalp:
  • Avoid excessive heat when drying or styling hair.
  • Avoid harsh chemicals such as dyes or perms.
• Maintain proper hair and scalp hygiene with gentle washing.
• Protect hair from heat using hats and scalp sun protection products.
• Follow a balanced diet rich in iron, zinc, and protein.
• Do not smoke.
• Avoid stress whenever possible.

To slow progression once scarring alopecia has begun, it is important to pay attention to early scalp changes and address them promptly. Early signs typically include redness, scaling, or itching.

Which specialist treats scarring alopecia?

Scarring alopecia is managed within the specialty of Medical-surgical dermatology and Venereology.