Hypopigmentation means reduced melanin, the pigment that gives skin its colour. It describes a colour change rather than a diagnosis, so the long word has not done the diagnostic work. Completely white patches are called depigmentation, meaning skin colour is absent rather than just reduced. Neither term tells you by itself whether the affected area will expand.34

Which causes can spread?

Vitiligo can begin with a few small pale patches. Existing patches can enlarge, and new patches can appear nearby or elsewhere. Some patches stay the same size for years; others grow and join together. There is no reliable way to predict how much skin will eventually lose colour. A pale patch can also gradually become white, which is a change in colour, not necessarily an increase in size.15

The pattern depends partly on the type of vitiligo:

  • Nonsegmental vitiligo usually affects both sides of the body. It tends to spread slowly, with new patches appearing off and on throughout life.
  • Segmental vitiligo affects one side or part of the body. It usually spreads rapidly for 6 to 12 months, then stabilises. Most people do not develop new patches once it has stabilised.
1

Pityriasis versicolor, also called tinea versicolor, is another cause of lighter patches. It happens when a fungus normally living on the skin grows more than usual. Patches commonly appear on the chest, upper back, upper arms, neck or tummy. They can feel scaly, sometimes itch, and join into larger areas. The infection usually needs antifungal treatment; skin colour can take a few months to return afterwards.6

When do lighter patches fade instead?

Lighter patches can remain after eczema, psoriasis, burns or other skin injuries. This is called postinflammatory hypopigmentation: colour loss following inflammation. Pigment often returns over weeks to months once the underlying inflammation or infection has cleared. Laser treatments and chemical peels can also leave lighter areas. A pale scar is different from a healing patch with temporarily reduced pigment: colour loss from scarring can be permanent.24

Can it spread to another person?

Spreading across your own skin is different from being contagious. You cannot catch vitiligo from someone or pass it on. Pityriasis versicolor also cannot spread from person to person, despite being a fungal infection. Neither condition means that you are not washing properly.16

What should you do if patches are spreading?

Arrange a medical assessment for new or enlarging pale patches rather than assuming they are vitiligo. A clinician will examine your skin and ask about previous rashes, injuries and treatments. A Wood's lamp, a specialised ultraviolet lamp, can make pigment changes easier to see and help distinguish vitiligo from other causes. Tell the clinician if new patches are appearing frequently, because rapidly progressing vitiligo can change the treatment plan.57

Vitiligo treatment can reduce further colour loss in some people, but it cannot reliably prevent all future spread or cure the condition. Options include prescription skin medicines and light therapy; a dermatologist can consider oral medicine when new patches are developing quickly. Colour returns gradually when treatment works, and maintenance treatment is often needed. Starting treatment sooner tends to make it more effective.157

Use sunscreen with SPF 30 or higher on lighter areas, which are more vulnerable to sun damage. Makeup or self tanner can make pale patches less visible, but their job description ends at appearances. Seek medical care for pale changes around the genitals or anus, where lichen sclerosus is one possible cause. Also ask for help if the colour changes are causing stress, anxiety or depression.2

Where this answer comes from

  1. 1Vitiligo: FAQsaad.org
  2. 2Hypopigmentation: What It Is, Causes & Treatmentmy.clevelandclinic.org
  3. 3Skin pigmentationdermnetnz.org
  4. 4Pigmentation disordersdermnetnz.org
  5. 5Vitiligonhs.uk
  6. 6Pityriasis versicolornhs.uk
  7. 7Vitiligo: Diagnosis and treatmentaad.org