A number of causes are related for the occurrence of pityriasis alba white/pale spots and patches on the face and body of children. But the knowledge of real reason is elusive.
Pityriasis alba is considered as an atopic dermatitis occurring in children, especially on their face, shoulders and arms and could be an independent eczema. The exact causes of these white spots is not known. The investigations of skin scrapings of a number of patients have indicated non involvement of bacteria and fungus.
Pityriasis alba is not contagious and has no definite etiologic agent. Studies have revealed that the hypopigmentation is due to reduction in the numbers of functional melanocytes and decrease of melanosomes in size and number. Dryness of skin, especially in winter appears to aggravate this ailment and increase the scale formation.
We can infer that cold dry condition may trigger and cause it in persons predisposed to it. In summer months, though the patches appear prominent due to tanning of the surrounding skin, there is no aggravation of the condition. Another hypothesis is that the deficiency of calcium and related vitamins precipitates this pityriasis ailment.
The explanation and reasoning is that pityriasis alba often occurs during the growing years of children. The growing children tend to get deficient in vitamins and calcium easily. Infestation with intestinal worms and parasites has been associated with pityriasis alba occurrence. In rural India deworming of the children is done by feeding them with a spoon of Castor oil with the belief that the condition will resolve.
Some theories have associated public swimming pools as one of the reasons of occurrence of pityriasis alba. Though the condition is asymptomatic for the affected child, it is of a big worry for the parents. Schools and daycare facilities will be very apprehensive about pityriasis alba and its causes and may insist on evaluation of the infective status of the condition.