In his new series GP and hospital practitioner Dr Andy Jordan will advise on how to differentiate between two often similar looking skin conditions
A number of conditions can cause scattered depigmented patches but pityriasis versicolor and vitiligo are two of the commonest.
Pityriasis versicolor is an infection with the yeast Malassezia furfur – while vitiligo is an autoimmune condition
They may both present with truncal patches and both lesions are sharply demarcated. But there are a number of distinguishing features.
Pityriasis versicolor
• Affects both genders equally
• Usually occurs in teenagers or young adults
• Tends to affect the trunk and neck and occasionally the upper arms.
• Asymmetrical
• It may be mildly irritant
• Lesions have fine, superficial scaling, highlighted by stretching the skin or blunt scraping
• On white skin affected areas are darker than normal with orange/brown hue
• Affected skin does not tan, as azelaic acid produced by years stops melanin production
• Depigmentation may persist for some months after successful treatment
• May be pale yellow fluorescence under Woods light
Vitiligo
• Affects females more frequently
• Can develop at any age but frequently starts in late teens
• Often a family history of vitiligo or other autoimmune disease
• Pigment loss may be partial or complete- often with a margin of slight hyperpigmentation.
• Areas usually affected are face, hands, feet, elbows, knees, ankles and genitals.
• Lesions tend to be symmetrical- unlike P.versicolor
• Can demonstrate the Koebner phenomen, with areas of depigmentation developing in damaged areas of skin – well demonstrated in man with vitiligo after heart surgery (below, top picture).
• Halo naevi occasionally occur in association with vitiligo and depigmentation of hair can occur in affected areas (bolow, bottom picture)
• Treatment consists of cosmetic camouflage and sunscreen because the affected areas are prone to burning on sun exposure.
• The man with vitiligo in the photograph above also has lichen planus which can be seen to be Koebnerised on right wrist.
Dr Andy Jordan is GP and hospital practitioner in dermatology in Chesham, Buckinghamshire.
Picture 1 - Pityriasis versicolor Picture 1 - Pityriasis versicolor Picture 2 - Vitiligo with lichen planus Picture 2 - Vitiligo with lichen planus Picture 3 - Vitiligo in sternotomy scar Picture 3 - Vitiligo in sternotomy scar Picture 4 - Vitiligo halo naevis Picture 4 - Vitiligo halo naevis
