Actinic lentigo, commonly known as “sun spots” or “age spots,” is a prevalent, benign skin condition resulting from long-term exposure to ultraviolet (UV) radiation. These flat, pigmented marks appear on areas of the body that have received the most sun exposure over a person’s lifetime. While harmless, their appearance is often a cosmetic concern and signals underlying sun damage.
Understanding Actinic Lentigo
Actinic lentigines are a direct consequence of chronic UV radiation exposure, which disrupts the normal pigment-producing process in the skin. This exposure causes localized hyperactivity of melanocytes, the cells responsible for producing the skin pigment melanin. This increased activity leads to an accumulation of melanin within the keratinocytes, the main cells in the outermost layer of the skin, resulting in visible hyperpigmentation.
These spots typically present as flat, clearly defined patches, ranging in color from light tan to dark brown, and can vary significantly in size. They are found most commonly on the face, the back of the hands, the forearms, the shoulders, and the upper back, reflecting areas with the highest cumulative sun exposure. Unlike freckles, which often darken in the sun and fade during winter, lentigines persist year-round unless treated, indicating a more permanent change in the skin’s structure.
Distinguishing Actinic Lentigo from Other Skin Spots
Distinguishing benign actinic lentigo from potentially malignant lesions, such as lentigo maligna, is a significant concern. Actinic lentigines are uniform in color and shape, with distinct, regular borders. They represent a stable, non-cancerous proliferation of pigment cells.
Lentigo maligna, a form of melanoma in situ, can initially resemble a large, flat sun spot but displays specific atypical characteristics. The ABCDE rule helps identify suspicious spots that warrant professional examination:
- Asymmetry
- Border irregularity
- Color variation (multiple shades of brown, black, or blue/white)
- Diameter (greater than 6 millimeters)
- Evolving size, shape, or color
Any pigmented lesion that changes rapidly, bleeds, itches, or develops a raised nodule should be evaluated promptly by a dermatologist. While actinic lentigo is benign, its presence is a marker of significant sun damage, which increases the overall risk of developing skin cancers like basal cell carcinoma, squamous cell carcinoma, and melanoma.
Professional Treatment Options
Dermatologists offer several in-office procedures that effectively target and eliminate the excess pigment in actinic lentigo.
Cryotherapy
Cryotherapy involves briefly applying liquid nitrogen to the spot, causing a controlled, localized injury. This freezing destroys the cells containing concentrated melanin, leading to blistering and subsequent peeling of the treated area. The process reveals lighter skin underneath.
Laser Treatment
Laser treatment often utilizes Q-switched lasers, which emit short, high-energy pulses of light. This energy is selectively absorbed by the melanin pigment, breaking it down into tiny fragments that the body’s immune system clears away. Laser therapy is precise and minimizes damage to surrounding healthy tissue, though temporary post-treatment redness or darkening may occur.
Chemical Peels
Chemical peels use mild to medium-strength acids, such as trichloroacetic acid (TCA) or glycolic acid, to remove the outermost layer of the skin. Exfoliating the superficial pigmented cells promotes the growth of new, non-pigmented skin cells, resulting in a more even skin tone. This method can also address other signs of photoaging, such as fine lines and rough texture, across a wider area of skin.
Topical Agents
Prescription topical agents are used under medical supervision, particularly for widespread or numerous lentigines. Hydroquinone, typically in a 2% to 4% concentration, works by inhibiting the enzyme necessary for melanin production. Retinoids, such as tretinoin, increase skin cell turnover, helping to shed pigmented cells more quickly and improving the overall appearance of the spots.
Daily Prevention Strategies
Preventing the formation of new actinic lentigines centers on protection from UV radiation. The consistent application of a broad-spectrum sunscreen with a Sun Protection Factor (SPF) of 30 or higher is essential. Sunscreen must be applied generously to all exposed skin, including the hands, face, and neck, and reapplied every two hours when outdoors, especially after sweating or swimming.
Seeking shade, particularly during the peak sun hours between 10 a.m. and 4 p.m., significantly reduces UV exposure. Protective clothing provides a physical barrier against the sun’s rays. This includes wearing wide-brimmed hats, which shield the face and neck, and sunglasses that offer UV protection. Garments with an Ultraviolet Protection Factor (UPF) rating offer an added layer of defense against sun damage.