Pityriasis versicolor

Presented by

Dr. S.M. Ali Ahmed

Phase – B, MD( Microbiology) Resident

BSMMU

Introduction

• Pityriasis versicolor is a common skin complaint in which flaky

discolored patches appear mainly on the chest and back. The

term , Pityriasis’ is used to describe skin conditions in which

the scale appears similar to bran. The multiple colures arising

in the disorder give rise to the second part of the name,

‘versicolor’. It sometimes called ‘tinea versicolor’, although

the term ‘Tinea’ should strictly refer to infection with a

dermatophytes infection.

Cont….

• Recent research has shown that the majority of Tinea

versicolor is caused by the Malassezia globosa fungus,

although Malassezia furfur is responsible for a small number

of cases. These yeast are normally found on the human skin

and only become troublesome under certain circumstances,

such as a warm and humid environment, although the exact

conditions that cause initiation of infection

Cont…

The lesions of Pityriasis versicolor were first described by

Willan (1801), but the fungal nature of the organism was

recognized in 1846 by Eichsted. For more than 100 years,

other classifications were assigned to the genus and species.

However, the terminology "Malassezia yeasts" was given

taxonomic priority for lipophilic fungi that are part of the

normal flora of the skin.

Risk factors

• Hot climated, humidity

• Sweating

• Oily secretion

• Poor hygiene

• Pregnant

• Hormonal change

• Immunocompromised pt taking intralipid therapy

Types of Mallassezia

• Malassezia furfur

• M .sympodialis

• M. globosa

• M. obtusa

• M. restricta

• M. sloofiae

• M. Pachydermatis

Prevalence

• It is frequently seen in tropical regions, with prevalence as

high as 40 %; it is also common in temperate areas,

representing upto 3% of patients seen by dermatologist

during the summer month.

• Children age 0-15 years had a 17.8 % prevalence of pathogens

of the genus malassezia in the skin.

Cont..

The highest prevalence of colonisation is 23.3% in infants age

0-18 months

• 26.7% in 11-15 years olds.

• The species of Malasezia that are involved are M.globosa 77-

90%, m. sympodialis 32-42% , M.furfur 11%

Pathogenesis

• Altered pigmentation characterises PV. Historically, the colour

of these lesions was thought to vary according to sunlight

exposure, chronicity of the infection, and the patients' normal

pigmentation, with darker-skinned people exhibiting

hypopigmented lesions and lighter-skinned people exhibiting

hyperpigmentation.

• However, one study could find no correlation

between pigmentary variation in PV and duration

of infection or background skin colour. There are

multiple theories to explain the pigmentation

abnormalities for both hypopigmented and

hyperpigmented lesions in PV.

• Hyperpigmentation has been

explained by abnormally large

melanosomes,a thick stratum

corneum,and hyperaemia in

response to infection.

Cont…

Hypopigmentation has been explained by

• Damage to melanocytes

• Inhibition of tyrosinase by decarboxylic

acid

• Lipoperoxidase produced by Malassezia

species

• Melanosomes of small size

• Decreased numbers of melanosomes in

affected skin

• Blocking of UV light by lipid-like

material accumulating in the stratum

corneum due to Malassezia species.

Clinical Presentation

• Numerous spots and patches appear on the neck, upper

back,and shoulder

• The spots are covered by a fine scale

• The spots vary in size

• In summer, the spots are light and don’t tan like the normal

skin.

• In winter as normal skin tone fades, the spots look darker

then normal skin.

• Patients with tineaversicolor usually have many irregularly

shaped slightly scaling macule and patches, generally covering

large areas of the body and separated by skip region of

normal skin.The macules and patches are yellowish –brown,

pale yellow, or dark brown occationally reddish or pinkish,

apppear hypopigmented or hyperrpigmented.

Diagnosis of Pityriasis versicolor

• Wood’s lamp showing yellow or

brownish fluorescence in the

skin.

• Specimen : Skin

• M/E : KOH preparation

• Short, septate,unbranched ,blunt

ended fungal hyphae and mixture

of oval or cylindrical yeast cells

present.

• A charecterestic spaghetti and

meat ball appearance

culture

• Raised ,folded rough ,wrinkled dull,lobedmargin

M. Globosa

M. Furfur

M.Obtusa

Culture mediaSelective media :

SDA plus Olive oil :

Composition : Glucose 20 g

Peptone 10g

olive oil 10 ml

Chloramphenical .5g

Gentamicin .5 g

Cyclohexamide .5g

Agar 15 g

Dixon agar media :

Composition :

Malt extract -36g

ox bile 10 g

bacterial peptone 10 g

Tween 40 10 ml

glycerol 2ml

Oleic acid 2g

Chloramphenical and cyclohexamide .5g

Biochemical Test

Physiological M.F M. P M.S M.G M.O M.R M.slo

characteristics

Growth on Sa at 32° − + − − − - -

Growth on mDixon

32°C + + + + + + +

37°C + + + + +-or _ +-or+ +

40°C + + + - − - + -

Catalase reaction + + + + + - +

Esculin hydrolysis +- - + - + - -

Utilization of Tween: M,F M.P M.S M. G MO M.R M.Slo

Tween 20 + - - - - - +-or +

Tween 40 + + + - - - +

Tween 60 + + + - - - +

Tween 80 + + + - - - -

Tweeen 20, 40,60,80 precipitation test in M.furfur

• Tween 20,40,60,80 Precipitation test in M.globosa

Gram’s stain

• In Malassezia furfur :

Oval cylindrical or sperical or elipsoidalcell present. Pseudohyphae with fillamentous strain present

Gram stain

• In M.globosa

Spherical 2.5-8.0μm

fillaments with typical Spaghetti and meatball appearance present

Gram stain

• In Obtusa

cylindrical , budding yeast cell. Fillamentsmay be present.

Differential diagnosis :

• Pityriasis alba – round,oval,irregular plaques that are red ,pink scally andindistinct margin.usually 1-4 cm in diameter,common number 4or 5 to 20 or more.

• Pityriasis rosea :Discrete circular or oval lesions,

Scaling on most lesions, and Peripheral collarettescaling with central clearance on at least two lesions.

• Vitiligo –

Seborrheic dermatitis - patch is erythematous yellowish tint ,scales are greasy but in Pv is furfraceous.

Post inflamatory hypo and hyperpigmentation-

• Erythrasma-

Treatment

• Topical treatment : Selenium sulphide 2.5%

Econazole nitrate 1% cream

• systemic treatment :

Ketokonazole – 200 mg/day for 7-10 days

Fluconazole once oral dose of 400 mg

Itraconazole -200mg/ day for 5-7 days

Terbinafine – 250mg/day for 2 weeks