Hypopigmented patch on face- how to decide diagnosis in an MCQ- Important MCQ

A year old girl presents with ill defined hypopigmented patches on cheek with fine scaling. Her mother has a history of asthma. 

The best possible diagnosis is

a) Indeterminate hansens

b) Pityriasis alba

c) Pityriasis versicolor

d) Atopic dermatitis

Ans: b

Expl:

         

Pointer words for diagnosis of hypopigmented patch on cheek in children

Look for these phrases-	Diagnosis
Single/ few hypopigmented patches on cheek with fine scaling. No atrophy. Normal sensations on patch Personal/ family h/o atopy in the questions (eg: asthma, recurrent URTI, etc) Lesions come and go	Pityriasis alba (pityriasis= powder)
Single/ Few hypopigmented patches on cheek. No scaling Lesions show mild atrophy Sensations are usually normal Child from endemic areas like Bihar/ UP/ West Bengal,Tamil Nadu, etc	Indeterminate hansens
Multiple hypopigmented macules/ patches with scaling on scratching (scratch sign). Usually MCQ will say “multiple lesions on chest and trunk”, sometimes face. Perifollicular hypopigmentation (this word is often present in questions) Can occur in multiple shades of colours (brown/ hypopigmentated/red/pink) Woods lamp-greenish yellow fluorescence. KOH smear positive (spaghetti and meat ball appearance) no h/o atopy in the question	Pityriasis versicolor
Depigmented patches with/without leucotrichia (white hair)	Vitiligo
Depigmented/hypopigmented circular macule over centre of forehead in a female	Leucoderma due to bindi (agent causing it is para-tertiary butyl phenol)

                                   

Why not P. versicolor in this MCQ- see pic below ?

Typical pityriasis versicolor
Note the number of lesions. On scratching there will be fine scaling
(Ref:ehow)

Typical pityriasis versicolor on face

Note the number of lesions. On scratching there will be fine scaling

(Ref:skinsight.com)

Why not Atopic dermatitis?

                                           Typical atopic dermatitis in children (Ref:www.salineherapy.com)

    Note erythema, oozing and inflammation
 (Atopic dermatitis is itchy, P.alba is not.There is no hypopigmentation in atopic dermatitis)

     

Also, for diagnosis of atopic dermatitis, these criteria have to be fulfilled: 

Typical Adult atopic dermatitis

Note the erythema, oozing and inflammation in flexure of knee

(Ref:www.derm-image.org)

Above: Typical change in sites of lesions in atopic dermatitis with age groups

Typical bindi leucoderma on central forehead

Note the depigmentation and white hairs