No one is exactly sure what causes vitiligo, but genetics, illness and damage to the skin may be causes. Some drugs may even cause patches of skin to lose pigment.   Stress and illness may also make it worse, causing larger patches of skin to lose pigment.   It's not possible for anyone on this site to tell you for sure that exposure to cockroach allergen is causing pigment loss in your skin. If you're really concerned, you should see your doctor to get a definitive diagnosis. According to the NIH page on vitiligo: Examination is usually sufficient to confirm the diagnosis. In some cases, a skin biopsy may be needed to rule out other causes of pigment loss. Your doctor may also perform blood tests to check the levels of thyroid or other hormones, and vitamin B12 levels. To your health, Joy B.