Patchy skin color refers to areas of irregular skin coloring. Mottling or mottled skin refers specifically to blood vessel changes in the skin which cause a patchy appearance.

Irregular or patchy discoloration of the skin can be caused by:

• Changes in pigment (melanin), a substance produced in the skin cells that gives skin its color
• Blood vessel (vascular) changes
• Growth of foreign organisms on the skin

Mottling or mottled skin refers specifically to blood vessel changes in the skin.

Melanin may be affected by genetics, heat, injury, solar or ionizing radiation, heavy metals, and other factors. Pigment production and distribution in the body is control in part by hormones. Changes in any of these factors can increase or decrease pigment production.

• Increased pigment production is called hyperpigmentation.
• Decreased pigment production is called hypopigmentation.

Exposure to sun or ultraviolet (UV) light, especially after sensitization with a medicine called psoralens, may increase pigmentation. This may increase the risk for skin cancer.

Skin color changes can be a single disorder, or they may result from other medical conditions or disorders.

Your degree of skin pigmentation determines, to some extent, the skin diseases to which you may be susceptible. For example, lighter-skinned people are more sensitive to sun exposure and damage, which raises the risk for basal cell carcinoma, squamous cell carcinoma and melanoma.

However, excessive sun exposure is a risk factor even for darker-skinned people.

Generally, pigment changes are cosmetic and do not affect physical health. However, psychological stress can occur because of pigment changes. Some pigment changes may indicate a risk for other disorders.

• Cafe-au-lait spots
• Chloasma
• Cuts, scrapes, wounds, insect bites and minor skin infections
  • In darker-skinned people, skin damage may cause permanent hyperpigmentation
• Erythrasma
• Melasma
• Melanoma
• Moles (nevi), bathing trunk nevi, or giant nevi
• Mongolian blue spots
• Photosensitivity as a reaction to medications or certain drugs
• Pityriasis alba
• Radiation therapy
• Rashes
• Sunburn or sun tan
• Tinea versicolor
• Uneven application of sunscreen resulting in areas of burn, tan, and no tan
• Vitiligo

Normal skin color may return on its own in some cases.

Lotions that bleach or lighten the skin, such as hydroquinone, may be used to reduce hyperpigmented skin or to even the skin tone where hypopigmented areas are large or very noticeable.

Selsun blue or tolnaftate (Tinactin) lotion can help in treating tinea versicolor. Apply as directed to the affected area daily until the lesions disappear. Unfortunately, tinea versicolor often returns no matter what type of treatment is used.

Cosmetics or skin dyes may be used to disguise skin color changes. Makeup can help hide mottled skin but will not cure the underlying problem.

Avoid excessive sun exposure and use sun block. Hypopigmented skin sunburns easily, and hyperpigmented skin may get even darker.

Contact your doctor if you have any persistent skin coloring changes without a known cause.

Also call if you you notice a new mole or other growth, or if an existing one has changed color, size, or appearance.

The doctor will carefully examine the skin and ask questions about your medical history and symptoms, such as:

• When did the skin coloring change develop?
• Did it develop slowly or suddenly?
• Is it getting worse? How fast?
• What is your normal skin color?
• Does the skin coloring change appear in more than one location?
• Have you had any injury to the skin (including sunburn or frequent sun tans)?
• Are you pregnant?
• What medications do you take?
• What medical treatments have you had?
• What other symptoms do you have?

Tests that may be done include:

• Scrapings of skin lesions
• Skin biopsy
• Wood's lamp (ultraviolet light) examination of the skin