Pityriasis versicolor

Question 1

What is pityriasis versicolor?

Answer 1

= flakes of variable colour

• fungal skin infection, superficial
• caused by MALASSEZIA
• often asymptomatic except for flaky appearance
• pale white, brown or pink patches
• persist for months or years

Other fungal skin would be tinea (dermatophytes ie ringworm) or candida. This is Malassezia.

Malassezia also causes seborrhiec dermatitis and pityriasis capititus (dandruff).

• more common in hot, humid, sweaty

(used to be called tinea versicolor!)

Question 2

Clinical features of pityriasis versicolor?

Answer 2

• dry scaly rash
• well demarcated, often circular patches (can coalesce)
• affects trunk
• young and middle aged
• slow onset over months / years
• not itchy
• often recurs in summer months

Question 3

Differential diagnoses when considering pityriasis versicolor?

Answer 3

• discoid eczema (itchy!)
• guttate psoriasis (look for lesions elsewhere)
• Pityriasis rosea (rapid onset, herald patch, pink, itchy)
• seborrheic dermatitis (face and scalp, more scaly)
• tinea corporis
• vitiligo (completely white patches)

Question 4

Pathology of pityriasis versicolor?

Answer 4

Melassezia funguses produce acetic acid - diffuses down and affects melanocyte functioning causing paler patches.

Patches do not tan.

Question 5

Diagnosis of pityriasis versicolor?

Answer 5

Can be clinical.

Can confirm with skin scrapings:

• will fluoresce blue-green on Wood’s lamp examination (UV light)
• potassium hydroxide preparation will show clusters of yeast and long hypi (“spaghetti and meatballs” appearance)
• malassezia is hard to grow in lab
• 7 species
• unaffected people also grow malassezia

Question 6

Management of pityriasis versicolor?

Answer 6

Topical agents for 2 weeks
- scaling resolves fairly quickly, colour takes a while

• “-azoles” eg fluconazole, ketoconazole are most effective antifungals for malassezia

Topicals:

• selenium sulphide “selsun yellow shampoo”
• “azoles” shampoo, keep 5 mins, 10 days
• sodium thiosulfate (leave for 10 mins or overnight then wash off)

Oral:
- fluconazole, ketaconazole for resistant / recurrent cases

Prophylaxis for recurrent cases:
- itraconazole 200mg monthly

Wash with anti-dandruff shampoo in future to reduce recurrence.