ABSTRACT

A 12-year-old boy attended the paediatric department for an examination as an area of linear bruising across his left chest had been noted at school. He said he could not remember but thought he had knocked his chest on the floor when he fell the previous day. The paediatrician noted four bars of parallel bruising to the boy’s left chest and a group of four small round bruises on his left upper arm. He also found a large area of depigmentation on the boy’s face (Image 91) which was said to have happened when he pulled a hot cup of tea onto himself when he was 2 years old. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429170423/e1d751c1-a9c7-4bb9-9d59-53742c84031a/content/fig91.jpg"/>

What is the diagnosis and differential diagnosis of the area of depigmentation?

What is the aetiology of the condition?

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This boy was the victim of non-accidental injury. He later said that the bruising to the chest had been caused when his mother hit him when she was angry after he had dropped a cup. The marks on his arm were where she gripped him. Vitiligo is the cause of the area of depigmentation. The differential diagnosis includes such conditions as tinea versicolor and post-inflammatory hypopigmentation or an area of scarring. The latter is unlikely as the surface of the depigmented skin is normal, the same as the adjacent area of pigmented skin.

There is still a debate about the cause of vitiligo which is a polygenic disorder with complex pathogenesis, linked to genetic and non-genetic factors. 1 Suggested causes include destruction of the melanocytes because of an accumulation of a toxic melanin synthesis intermediate or that neurochemical factors damage melanocytes or even that immunological factors damage the melanocytes. The latter cause might explain why 80% of cases have an antimelanocyte antibody. There is also an incidence of autoimmune diseases such as Hashimoto thyroiditis and Addison disease in patients with vitiligo.