Actinic Keratosis: Symptoms, Types, Causes and Treatment

Actinic keratosis (AK) is a common skin condition that often goes unnoticed, yet it can have significant implications for both skin health and overall well-being. With its origins rooted in chronic sun exposure, AK not only affects the appearance and texture of the skin but can also progress to more serious skin cancers if left untreated. Understanding the symptoms, types, causes, and available treatments is crucial for early detection and effective management. In this comprehensive guide, we’ll unravel the complexities of actinic keratosis, providing you with clear, actionable information.

Symptoms of Actinic Keratosis

Actinic keratosis often begins subtly, making it easy to overlook in its early stages. Recognizing the symptoms early can help prevent progression to more severe skin conditions.

Surface	Color	Sensation	Source
Rough	Red/pink	Itchy or tender	1 2 5 11 16
Scaly	Brownish	Burning or stinging	1 2 5 12 16
Bumpy	Skin-colored	May bleed or crust	1 2 12 16
Dry	Grayish	No symptoms (often)	1 12 16

Table 1: Key Symptoms of Actinic Keratosis

Recognizing the Signs

Actinic keratosis lesions are typically found on sun-exposed areas such as the face, scalp, ears, neck, forearms, and the backs of the hands. These lesions may present in several ways:

• Texture: The most characteristic sign is an irregularly rough, sandpaper-like texture. Even before they are visible, AKs can often be felt as a patch of roughness that stands out from surrounding skin 2 5 11.
• Color: Lesions vary in color, ranging from pink, red, or brown to skin-colored or grayish. They may also appear as slightly raised patches or flat spots 5 11 12.
• Sensation: Some people experience itchiness, burning, or tenderness in the affected area, while others do not notice any discomfort 1 2 12.
• Surface: AKs can appear as scaly, dry, or bumpy patches; sometimes, they may develop a wart-like, crusted, or even horn-like surface (cutaneous horn) 2 12.
• Symptoms Progression: Over time, lesions can become thicker, more irritated, or even bleed or form a crust 2 16.

Impact on Daily Life

Beyond the physical symptoms, actinic keratosis can have an emotional and functional impact. Studies show that people with AK often report distress about the appearance of their skin, which can affect self-esteem and daily activities. Treatment with topical agents like tirbanibulin has been shown to significantly reduce these symptoms and improve quality of life 1.

Types of Actinic Keratosis

Not all actinic keratoses are the same. They vary in appearance, thickness, and risk of progression to skin cancer. Understanding the types helps guide both diagnosis and treatment decisions.

Clinical Type	Histological Grade	Distinct Feature	Source
Classic (Papular)	AK I (Basal)	Thin, slightly raised, rough	3 4 5 6
Hypertrophic	AK II (Partial)	Thick, scaly, wart-like	5 6 12
Atrophic/Non-keratotic	AK III (Full)	Flat, ill-defined, red patch	5 6 12
Cutaneous horn	—	Horn-shaped, protruding	2 12

Table 2: Types and Grades of Actinic Keratosis

Clinical and Histological Classification

Olsen Clinical Classification

The Olsen system grades AKs by their thickness and hyperkeratosis:

• Grade 1: Slightly palpable, better felt than seen
• Grade 2: Moderately thick, easily seen and felt
• Grade 3: Very thick, obvious hyperkeratosis or wart-like 6

Roewert-Huber Histological Classification

This system categorizes AKs by the depth of abnormal keratinocyte involvement:

• AK I: Atypical cells confined to the basal layer
• AK II: Atypical cells extend into lower two-thirds of the epidermis
• AK III: Full-thickness involvement of the epidermis 3 4 5 6

Special Forms

• Cutaneous Horn: A distinct, cone-shaped projection of keratin, often with underlying AK, especially in older adults 2.
• Merging/“Patch” AK: Large, confluent areas of affected skin, which may have a higher risk of progression to squamous cell carcinoma (SCC) 7.
• Non-keratotic (Atrophic) AK: Flat, red, and less scaly, often confused with other skin conditions but still carries malignant potential 2 12.

Why Classification Matters

Proper classification helps determine:

• Risk of malignancy (deeper or more confluent lesions may be riskier) 3 4 7
• The best treatment approach (thin vs. thick lesions may respond differently) 6 14

Causes of Actinic Keratosis

Understanding what causes actinic keratosis is key to both prevention and management. While sun exposure is the leading culprit, several factors play a role in its development.

Cause	Risk Factor	Mechanism	Source
UV Radiation	Fair skin, outdoor work	DNA damage to skin cells	2 5 8 9 10 11 12
Immunosuppression	Organ transplant, HIV	Reduced surveillance of abnormal cells	2 8 12
Genetics	Xeroderma pigmentosum	Impaired DNA repair	2 5
HPV Infection	—	Promotes cell growth	8 12

Table 3: Main Causes and Risks for Actinic Keratosis

Ultraviolet (UV) Exposure: The Prime Factor

• Chronic sun exposure is responsible for the vast majority of AK cases. UVB rays cause direct DNA mutations in skin cells, while UVA contributes through oxidative stress and immunosuppression 2 5 9 11.
• Cumulative exposure over years intensifies risk; even brief, intense sun exposure during childhood can contribute 2 5 8.

Additional Risk Factors

• Fair Skin Types: People with Fitzpatrick skin types I and II (pale, burn easily) are most susceptible 2 5 8 12.
• Age and Gender: AK is more common in older adults and men, likely due to greater lifetime sun exposure 2 12.
• Immunosuppression: Organ transplant recipients, those on immunosuppressive drugs, or people with HIV/AIDS have a much higher risk 2 8 12.
• Genetic Disorders: Rare conditions like xeroderma pigmentosum or albinism, which affect DNA repair or pigmentation, dramatically increase susceptibility 2 5.
• Human Papillomavirus (HPV): Some evidence links HPV infection to AK development, probably by promoting abnormal cell growth 8 12.

How AK Develops: The Pathophysiology

• UV-induced DNA damage leads to abnormal keratinocyte (skin cell) proliferation and mutation.
• Other mechanisms include inflammation, oxidative stress, impaired apoptosis (cell death), and tissue remodeling 8 9 12.
• Over time, these changes result in visible lesions that can remain stable, regress, or progress to invasive squamous cell carcinoma 8 9.

Treatment of Actinic Keratosis

Treating actinic keratosis is essential to prevent progression to skin cancer and to improve skin appearance and comfort. There are multiple treatment options, ranging from local therapies for single lesions to broader field treatments for widespread sun damage.

Approach	Example	Use Case	Source
Lesion-Directed	Cryotherapy, Curettage	Isolated lesions	8 14 16
Field-Directed	5-FU, Imiquimod, PDT	Multiple lesions/large areas	8 13 16
Combination	Cryo + Creams	Resistant or recurrent AK	8 12 16
New Agents	Tirbanibulin	Rapid, topical, mild AK	1 15

Table 4: Treatment Options for Actinic Keratosis

Lesion-Directed Treatments

Cryotherapy

• How it works: Freezes and destroys abnormal cells with liquid nitrogen.
• Best for: Isolated, thick, or small number of lesions.
• Advantages: Quick, effective, minimal downtime.
• Drawbacks: May cause blistering, pigment changes, or scarring 14 16.

Curettage & Excision

• How it works: Scrapes off the lesion, sometimes followed by cautery.
• Use: For thicker or suspicious lesions, or those needing biopsy 14 16.

Field-Directed Therapies

Topical 5-Fluorouracil (5-FU)

• How it works: Chemotherapy cream that targets abnormal cells.
• Effectiveness: Most effective for widespread AK, especially on the face and scalp. In a large trial, 5% fluorouracil cream had the highest efficacy at 12 months compared to other leading field treatments 13 16.
• Side effects: Redness, irritation, temporary discomfort 13.

Imiquimod

• How it works: Stimulates local immune response to destroy abnormal cells.
• Effectiveness: Highly recommended; may be less effective than 5-FU for field treatment, but useful in certain patients 13 16.

Photodynamic Therapy (PDT)

• How it works: Photosensitizing agent plus light exposure destroys atypical cells.
• Use: For multiple lesions, especially in cosmetically sensitive areas.
• Advantages: Good cosmetic results 8 16.

Diclofenac, Ingenol Mebutate, and Others

• How they work: Alternative topical or gel-based therapies with moderate efficacy.
• Use: When other treatments are unsuitable or as adjuncts 8 12 16.

Novel and Combination Therapies

Tirbanibulin

• How it works: Inhibits tubulin polymerization and Src kinase signaling in abnormal cells.
• Evidence: Short, 5-day course is effective for facial/scalp AK, with substantial symptom relief and improved quality of life, though recurrences can occur 1 15.
• Side effects: Local redness, scaling, transient pain or itching 15.

Combination Approaches

• Rationale: Combining lesion- and field-directed therapies can improve effectiveness, reduce duration, and minimize side effects 8 12 16.

Prevention and Education

• Sun Protection: Regular use of sunscreen, protective clothing, and avoidance of peak-sun hours is the most effective way to prevent AK 12 16.
• Patient Education: Understanding risk factors, early signs, and the importance of regular skin checks is vital 12 16.

Conclusion

Actinic keratosis is more than just a cosmetic concern—it is a visible warning sign of chronic sun damage and carries a real risk of progression to skin cancer. Early recognition, accurate classification, and prompt, appropriate treatment can make a significant difference in outcomes.

Key Takeaways:

• AK usually presents as rough, scaly, or bumpy patches on sun-exposed skin, often with subtle symptoms 1 2 5 11.
• There are various clinical and histological types, ranging from thin, flat lesions to thick, wart-like growths, some merging into larger patches 3 4 5 6 7 12.
• Chronic ultraviolet exposure is the main cause, with fair skin, age, immunosuppression, genetics, and HPV as important risk factors 2 5 8 9 10 11 12.
• A variety of lesion- and field-directed treatments exist, with 5-fluorouracil, imiquimod, and cryotherapy among the most effective; new options like tirbanibulin are expanding the therapeutic arsenal 8 13 15 16.
• Prevention—especially sun protection—remains the cornerstone of reducing AK risk and recurrence 12 16.

By staying vigilant and proactive about skin health, individuals can reduce their risk of actinic keratosis and enjoy healthier, more resilient skin for years to come.