Hi. Welcome to HCM. Skin pigmentation disorders are conditions that cause the skin to appear lighter or darker than normal, or blotchy and discolored.n hyperpigmentation, the body produces too much melanin, causing skin to become darker than usual. Lichen simplex chronicus is a skin disorder with severe itching that causes thick, dark patches of skin to develop. Lamellar ichthyosis (fish scale disease) is an inherited disease that also is characterized by darkened, scaly, dry patches of skin. Diagnostic tests vary for different types of skin pigmentation disorders. Physicians usually can diagnose albinism by looking carefully at a person s hair, skin, and eyes. They may order blood tests and eye exams as well. A visual exam also is enough to diagnose vitilgo. So you better consult an dermatologist.