The 2012 edition of The Skin Cancer Foundation Journal features medically reviewed, reader-friendly articles such as tanning, the increasing incidence of skin cancer diagnoses among young women, & the prevalence of melanoma among white males over 50.
Issue link: http://skincancer.epubxp.com/i/65757
Watch Out for Aggressive Precancers MICHAEL P. LOOSEMORE, MD ADISBETH MORALES-BURGOS, MD LEONARD H. GOLDBERG, MD T he fact that actinic keratosis (AK) is termed a precancer might make you think these scaly or crusty growths (lesions) aren't serious, but in some instances they can be dangerous. AKs affect more than 58 million Americans,1 and as part of the spec- trum of non-melanoma skin cancers, form the most common group of dis- eases encountered by dermatologists. AK is an abnormal growth of keratino- cytes, the skin cells that make up the top layer of the skin (the epidermis). [See Figure 1, p.62.] Like basal cell carcinoma and other skin cancers, AKs (a.k.a. solar keratoses) are largely initiated by the sun's ultraviolet (UV) radiation. That's why using sun protec- tion and avoiding UV tanning beds is paramount to prevention of both AKs and skin cancers. Most actinic keratoses appear as pink or red scaly or crusty spots. They are often easier to feel than see, as they may be tender and/or rough to the touch. AKs may be single or multiple, localized or involving a large area, small or big, thin or thick. AKs are most often found on sun-exposed areas such as the face, head, neck, and arms. AGGRESSIVE AK AND SCC Some AKs can be aggressive, and are much more prone to develop into squamous cell carcinoma (SCC), the second most common skin cancer. In typical AKs, the abnormal cells involve partial thickness of the epidermis, but when an AK grows to involve the full thickness of the epidermis it becomes an SCC.2 of SCC are diagnosed every year in the US,3 of them arise in lesions previously diagnosed as AKs.4 and an estimated 65 percent SCCs can invade the dermis, the layer of skin beneath the epidermis; these invasive SCCs may occasionally spread to other parts of the body and can become life- threatening. Aggressive AKs can also reach the dermis, extending into the hair and sweat follicles, which makes them more resistant to treatment. Aggressive AKs tend to be over one cm in diameter, thicker, and involve a wider area than regular AKs. Some AKs can be aggressive and are much more prone to develop into squamous cell carcinoma (SCC), the second most common skin cancer. and the same, though with different growth patterns. PAK may spread subclinically (below the skin's surface microscopically), hiding in the depths of the dermis. The authors have experience with four cases of metastatic (spreading) SCC — which can be life-threatening — that developed from PAKs. PAKs and other deeper AKs can be diagnosed only by biopsy, which should be considered in all treatment-resistant AKs. TREATING AGGRESSIVE AKS AK therapies may be localized and lesion-targeted, as with cryotherapy, curettage and desiccation, or broader in coverage and superficial, like topical medications. However, because PAKs and other aggressive AKs can invade the dermis, it is difficult for topical therapies to reach the tumors and destroy the malignant cells. Cryotherapy with liquid nitrogen is a treatment option for all AKs, especially lesions suspected of ex- tending into the dermis, like PAKs. AKs affect more than 58 million Americans,1 58 million+ and as part of the spectrum of non-melanoma skin cancers, form the most common group of diseases encountered by dermatologists. described in 1994, is a specific subtype of these aggressive AKs.5 Proliferative AK (PAK), first PAKs are About 700,000 cases larger than most AKs, have micro- scopic ulcerations (broken skin) on the surface, and grow significantly over time [Figure 2]. We have found a close association between PAK and invasive SCC, indicating that these tumors can be comparably aggressive. When exam- ined under the microscope [Figure 3], the cells of a PAK are often identi- cal to those of an adjacent invasive SCC. This suggests that both groups of abnormal cells are actually one 65% 700,000 About 700,000 cases of SCC are diagnosed every year in the US,3 and an estimated 65% of them arise in lesions previously diagnosed as AKs.4 61