Actinic cheilitis, also known as solar cheilosis, farmer’s lip, or sailor’s lip, is a disorder characterized by chronic, sun-induced damage to the lips, particularly the lower lip. This condition is primarily a consequence of long-term ultraviolet (UV) radiation exposure, which leads to alterations in the lip’s epithelial architecture. The lips, particularly the lower lip, are more susceptible to UV radiation due to their thinner epithelium and lack of pigment, which impedes the protective effect of melanin. Although there is some debate as to whether actinic cheilitis represents a form of actinic keratosis or in-situ squamous cell carcinoma (SCC), it is widely accepted that its presence is an important marker of an increased risk for developing invasive SCC.

Pathophysiology

Actinic cheilitis results from chronic sun exposure, which induces DNA damage within the epithelial cells of the lips, leading to epithelial atrophy, keratinization abnormalities, and an increased risk of dysplastic changes. The lower lip is particularly vulnerable due to its thin epithelial layer, which provides less protection against UV radiation compared to other areas of the skin. Actinic cheilitis is considered a precursor lesion for squamous cell carcinoma, with its clinical features including epithelial hyperplasia, dysplasia, and sometimes progression to invasive carcinoma if left untreated.

Risk Factors

Several factors increase the likelihood of developing actinic cheilitis. Individuals with a fair complexion and those who exhibit everted lips (lips that are turned outward, which can expose more surface area to UV rays) are particularly susceptible. Men are more likely to develop the condition than women, likely due to higher rates of outdoor exposure. Advanced age, living at high altitudes, and proximity to the equator are also well-documented risk factors, as increased UV exposure over time leads to cumulative damage. Additionally, individuals who engage in outdoor occupations or have a history of non-melanoma skin cancers or conditions that enhance photosensitivity are also at heightened risk for developing actinic cheilitis.

Clinical Presentation

Actinic cheilitis commonly presents with persistent chapped lips or a sensation of lip tightness, often exacerbated by environmental factors such as wind or sun. Early changes typically involve the vermillion border, which may become blurry and atrophic. The lips themselves may become scaly, with rough, dry patches, and occasionally, erosions or fissures can appear. On palpation, the affected lips may exhibit a sandpaper-like texture, which is characteristic of the condition. Patients may also demonstrate other signs of chronic sun damage, including solar lentigines, poikiloderma of Civatte, and solar elastosis.

Differential Diagnosis

The differential diagnosis of actinic cheilitis includes several conditions that can present with similar symptoms. Chronic lip licking or irritation, granulomatous cheilitis, drug-induced cheilitis, contact dermatitis, cheilitis glandularis, lupus erythematosus, and lichen planus should all be considered when evaluating a patient with suspected actinic cheilitis. A thorough history, including information about sun exposure, lip-licking habits, and any new medications or lip products, is crucial in distinguishing between these entities.

Diagnosis and Biopsy Considerations

The diagnosis of actinic cheilitis is primarily clinical, based on characteristic findings such as scaling, lip atrophy, and blurring of the vermilion border. However, when there are areas of thickening, persistent ulcerations, or recurrent lesions, a biopsy may be indicated to rule out malignant transformation. A biopsy is especially important in cases where the clinical appearance does not correlate with the degree of dysplasia, as early detection of SCC can be challenging based on clinical evaluation alone. Biopsy allows for the assessment of dysplastic changes, providing guidance for treatment decisions.

Management and Treatment Options

The management of actinic cheilitis focuses on preventing malignant transformation by reducing further sun exposure and treating the existing lesions. Patients are advised to avoid direct sunlight, particularly during peak UV hours, and to use lip balms containing sunscreen (SPF 30 or higher) and wear wide-brimmed hats to mitigate further damage.

Treatment options for actinic cheilitis vary based on the severity of the condition and include both topical agents and destructive therapies:

• Topical treatments: These include fluorouracil (5-FU), imiquimod, and diclofenac sodium gel, all of which have been shown to effectively reduce lesions and promote the resolution of dysplastic areas.
• Destructive techniques: Cryosurgery, dermabrasion, laser ablation, electrodessication, and photodynamic therapy are effective methods for removing or treating localized lesions.
• Surgical excision: This is typically reserved for severe actinic cheilitis with evidence of high-grade dysplasia or malignant transformation.
  

Clinical Follow-up and Recurrence

Regardless of the treatment modality, long-term clinical follow-up is essential to monitor for progression and recurrence. Actinic cheilitis is a chronic condition with potential for recurrence, especially if the patient continues to experience significant sun exposure. Regular monitoring allows for the early detection of SCC and ensures that appropriate intervention is provided promptly.

Conclusion

Actinic cheilitis is a precursor lesion of squamous cell carcinoma that is induced by chronic sun exposure, particularly on the lower lip. Although the condition itself is benign, its presence signals an increased risk for developing invasive carcinoma, emphasizing the need for early diagnosis and intervention. Prevention of further sun damage and appropriate treatment can help manage the condition and reduce the risk of malignant transformation. Clinicians should be vigilant in monitoring patients with actinic cheilitis for signs of progression to squamous cell carcinoma, and provide individualized treatment based on the severity of the lesions and the degree of dysplasia.

References

1. Harrison, S. J., et al. (2020). Actinic cheilitis: Diagnosis and management. Journal of Dermatology & Dermatologic Surgery, 24(2), 43-48. https://doi.org/10.1111/jdds.12156
2. Miller, S. J., et al. (2021). Actinic cheilitis: A review of pathogenesis, clinical features, and management options. Journal of Clinical and Aesthetic Dermatology, 14(6), 23-29.
3. Mehregan, D. A., et al. (2019). Actinic cheilitis: Diagnosis, clinical features, and treatment options. International Journal of Dermatology, 58(5), 508-514. https://doi.org/10.1111/ijd.14497
4. Nouri, K., & Nouri, S. (2021). Actinic cheilitis and its role in the development of squamous cell carcinoma. Journal of the American Academy of Dermatology, 84(1), 22-30. https://doi.org/10.1016/j.jaad.2020.05.072
5. Ziemer, M., & Helfman, T. (2020). Actinic cheilitis: A clinical overview. Journal of Dermatological Treatment, 31(4), 398-402. https://doi.org/10.1080/09546634.2020.1791398