A precancerous or premalignant lesion is one that has a strong likelihood of transforming into a malignancy. There is much debate about the validity of the concept of precancerous lesions, and the terminology has been confusing.1–4 Lesions discussed in this chapter are those that have a clinically demonstrated potential to become invasive carcinomas and are characterized by histologic atypia confined to the epidermis. The focus is only on the precancerous keratinocyte lesions and not on those of other epithelial cells such as the melanocyte, Merkel, and appendageal cells. Discussion of malignancies and premalignancies associated with these cells can be found in (Chapters 119, 120, and 123) respectively.
A common feature of all premalignant keratinocyte tumors (Table 113-1) is that they have the potential to become invasive squamous cell carcinoma (SCC). These precancerous lesions and SCC are considered by many to represent a continuum of disease with dysplasia at one end of the spectrum and invasive carcinoma at the other.
Table 113-1 Precancerous Keratinocytic Lesions ||Download (.pdf)
Table 113-1 Precancerous Keratinocytic Lesions
• Actinic keratoses (AKs)
• Arsenical keratoses (ArKs)
• Thermal keratoses (TKs)
• Hydrocarbon keratoses (HKs)
• Chronic radiation keratoses (CRKs)
• Reactional keratoses (RKs)
• PUVA keratoses
• Viral-associated precancerous keratinocytic lesions
• Bowenoid papulosis (BP)
• Epidermodysplasia verruciformis (EV)
• Bowen disease (BD) or squamous cell carcinoma (SCC) in situ
• Precancerous lesions of the lower anogenital tract
• Vulvar intraepithelial neoplasia (VIN)
• Anal (AIN) and perianal (PaIN) intraepithelial neoplasia
• Penile intraepithelial neoplasia (PIN)
• Potentially malignant disorders of the oral cavity
Actinic Keratoses at a Glance
- Precancerous lesions on a spectrum from photodamaged skin to squamous cell carcinoma (SCC).
- Strongest predictors of subsequent development of nonmelanoma skin cancer and melanoma.
- Risk factors include individual susceptibility, cumulative ultraviolet (UV) radiation exposure, immunosuppression, prior history of skin cancers, genetic syndromes.
- Long-term and cumulative UV radiation exposure is the most important contributing factor for development of actinic keratoses (AKs).
- Risk of progression of AK to SCC varies from less than 1%–20%.
- AKs should be treated because their course is unpredictable, they are often symptomatic, and they can progress to SCC if untreated.
- Treatment methods include cryotherapy, curettage with or without electrosurgery, shave excision, topical agents, and photodynamic therapy.
Actinic keratoses (AKs) or solar keratoses are cutaneous neoplasms consisting of proliferations of cytologically abnormal epidermal keratinocytes that develop in response to prolonged exposure to ultraviolet (UV) radiation. The concept of a precancerous keratosis was first presented by Dubreuilh in the late 1800s.5 AKs were first identified and named keratoma senilis by Freudenthal in 1926.6 In 1958, Pinkus further characterized these lesions and coined the term actinic keratosis.7 These lesions have also been called solar keratoses and senile keratoses. Actinic ...