Lentigines are common, typically harmless pigmented patches on the skin resulting from a localized increase in melanocytes (pigment-producing cells). These spots are often called “age spots” or “sun spots.” Unlike freckles (ephelides), which darken with sun exposure and fade in winter, lentigines maintain their color intensity year-round.
Visual Identification
Lentigines present as flat, well-defined macules, meaning they are level with the surrounding skin. Their color varies significantly, ranging from light tan or yellowish-brown to dark brown or black. These spots are usually small, often measuring only a few millimeters, but they can slowly expand over time. The edges of a lentigo are generally sharply circumscribed, though they may sometimes have a slightly irregular outline. The color within a single lesion is typically uniform, which helps distinguish them from other pigmented lesions that may exhibit multiple shades.
Primary Causes
The underlying mechanism for all lentigines involves a localized overgrowth of melanocytes in the basal layer of the epidermis. The most common trigger for this melanocyte increase is chronic exposure to ultraviolet (UV) radiation from the sun or tanning beds. This chronic UV damage leads to the development of the most frequent type of lentigo, often seen in adults with fair complexions. These lesions are referred to as “age spots” because they accumulate over a lifetime of sun exposure and become more prominent with age. Genetic predisposition can also play a role, particularly for non-sun-related types that appear in childhood.
Clinical Classification of Lentigines
Lentigines are separated into two main categories based on their cause and location. Solar lentigines are the most prevalent type, resulting directly from chronic sun exposure. These lesions are commonly found on areas that have received the most lifetime sun exposure, such as the face, the back of the hands, the shoulders, and the upper back. They are also known as “sun spots” or “senile lentigines.” The second category is the simple lentigo (or lentigo simplex), which is not associated with UV radiation. Simple lentigines usually appear in early childhood and can be found anywhere on the skin or mucous membranes. They tend to be smaller than solar lentigines, typically measuring between 3 and 15 millimeters.
When to Seek Medical Consultation
While the vast majority of lentigines are benign, a medical consultation becomes important when a lesion exhibits features that could suggest early melanoma, specifically a type called lentigo maligna. Dermatologists use the well-established ABCDE rule to help differentiate a harmless spot from a potentially serious one. This rule includes five key characteristics for self-monitoring:
- A stands for Asymmetry, where one half of the spot does not match the other.
- B is for Border irregularity, meaning the edges are ragged, notched, or blurred.
- C represents Color variation, especially if the spot has multiple shades of brown, tan, black, white, red, or blue within the same lesion.
- D is for Diameter, with a size greater than 6 millimeters (about the size of a pencil eraser) raising suspicion.
- E stands for Evolving, which is the most significant warning sign. This means the spot is changing in size, shape, color, or elevation over a period of weeks or months, or if it begins to itch or bleed.
If a lentigo develops any of these atypical features, a doctor, often using a magnified tool called a dermatoscope, can perform a closer examination to determine if a biopsy is necessary to rule out malignancy. Treatments like cryotherapy or laser removal are available for cosmetic reasons, but they are only pursued after the lesion is confirmed to be benign.