Vitiligo is a chronic skin condition characterized by patches of skin losing their natural color. This occurs when melanocytes, the specialized cells responsible for producing skin pigment (melanin), are destroyed. As a result, the affected areas appear lighter than the surrounding skin or become completely white.
What Vitiligo Looks Like
Vitiligo patches appear as milky-white areas on the skin. Their shapes are irregular, ranging from small, round spots to larger, more widespread configurations. The borders of these depigmented areas are well-defined, creating a distinct contrast with the surrounding pigmented skin.
Despite the color change, the texture of the skin within a vitiligo patch remains normal; it is not itchy, scaly, or raised. Hair growing in affected areas can also lose its pigment, turning white or gray, a phenomenon known as poliosis.
Different Forms of Vitiligo
Vitiligo manifests in several forms, primarily distinguished by the pattern and distribution of the depigmentation across the body. The most common classification includes generalized and segmental types, alongside less frequent variations.
Generalized vitiligo is the most prevalent type. It is characterized by widely distributed patches that appear symmetrically on both sides of the body. These patches can continue to spread and enlarge over time, sometimes affecting large areas of the skin.
Segmental vitiligo, in contrast, affects only one side or a specific segment of the body. This form presents in a linear or band-like pattern, following dermatomes. It starts at an earlier age and tends to spread more rapidly for a period before stabilizing, without further progression.
Other less common forms include focal vitiligo, where scattered patches appear in one isolated area. Universal vitiligo is a rare and extensive form where nearly all of the body’s skin loses its pigment, resulting in almost complete depigmentation.
The Cause of Depigmentation
The underlying biological mechanism responsible for the loss of skin color in vitiligo involves the selective destruction of melanocytes. The prevailing theory attributes this destruction primarily to an autoimmune response. In this scenario, the body’s own immune system mistakenly recognizes melanocytes as foreign or harmful and launches an attack against them.
This autoimmune attack leads to the targeted elimination of pigment-producing cells in the skin. While the exact trigger for this autoimmune reaction is not fully understood, a combination of factors is believed to contribute to its development. Genetic predisposition plays a notable role, as vitiligo often runs in families, indicating an inherited susceptibility.
Oxidative stress is another contributing factor, referring to an imbalance between free radicals and antioxidants in the body. Melanocytes are particularly sensitive to oxidative stress, and an excess of reactive oxygen species can damage or destroy these cells. Additionally, abnormalities in nerve cells within the skin have been implicated, suggesting that certain neurochemical imbalances might also contribute to melanocyte destruction. These interwoven factors collectively contribute to the complex etiology of vitiligo.
Common Locations of Vitiligo
Vitiligo patches can appear on any part of the body, but certain areas are more frequently affected due to their exposure or anatomical characteristics. These common locations often provide insights into the typical distribution patterns of the condition.
The face is a common site for depigmentation, particularly around the eyes, mouth, and nostrils. These areas are often exposed to sunlight, which can sometimes trigger or exacerbate the appearance of patches. Similarly, the hands and feet are frequently involved, with patches often appearing on the fingers, wrists, ankles, and toes.
Body folds, such as the armpits and groin, are also susceptible areas where vitiligo can develop. Furthermore, sites of previous injury, cuts, or pressure, known as the Koebner phenomenon, can manifest new vitiligo patches. This indicates that trauma to the skin might trigger depigmentation in predisposed individuals.
Mucous membranes, which line various body cavities, can also be affected. This includes the inside of the mouth, the nasal passages, and the genital regions. While the distribution can vary widely among individuals, these frequently affected sites highlight the diverse presentation of vitiligo on the human body.