QUESTION: A 17-year-old Vietnamese boy being admitted to a juvenile detection facility had linear, bruise-like lesions on his back. The possibility that he was a victim of child abuse was suspected after he claimed to have no knowledge of the cause of the bruising. Are there any other explanations for these marks?
ANSWER: The patient had symmetric linear groupings of petechiae on his back but at no other site. Initially, he claimed to have no idea about their cause. When the practice of coining (rubbing the skin firmly with the edge of a coin) was described to him, he admitted that his mother had engaged in coining him about 4 days previously. She had attempted to improve his breathing, using a method that is common in her country of origin, when she found him unconscious after an episode of illicit drug use. The young man was reluctant to discuss this incident because he was embarrassed by his mother's use of a technique that he considered archaic and un-American.
The petechiae resolved 4 days later. This episode was used to discuss with the patient his mother's concerns regarding his drug use. He was able to talk about the dangers of drug misuse in the context of the lifethreatening event he had experienced.
The symmetric, linear pattern of petechiae on the back is classic for coining. Bruises caused by inflicted trauma would usually be randomly distributed and often would involve more than one part of the body. Therefore, if the examiner is sure the lesions are petechiae, the next question to ask is what could have caused such carefully placed lesions. The clinician might also inquire as to why or how these marks came to be placed on the patient's back.
There are several differential diagnostic possibilities to consider in this case. Petechiae can be seen in various bleeding disorders involving low or abnormal platelet numbers. Bruising or purpura can also be seen in many different coagulopathies. In all of these bleeding disorders, the petechiae or bruising should be seen in other areas in addition to the back.
Other skin conditions are found on the back, but these are not predominantly petechial in their presentation. Pityriasis rosea consists of round and oval patches of salmon-colored lesions with a peripheral ring of scale. The patches follow the skin lines of the back and are aligned in diagonal rows like Christmas tree branches. Although somewhat symmetric, the lesions are not uniformly spaced. Occasionally the condition is intensely pruritic, and the patient may make many scratches that could resemble coining, although these excoriations don't generally look like the lines of petechiae characteristic of coining. Secondary syphilis can also mimic pityriasis rosea with quite dramatic papulosquamous lesions. All sexually active teenagers with these lesions should be tested for syphilis.
Lastly, phytophotodermatitis is caused by an interaction of a photosensitizing chemical and ultraviolet light. This disorder results in gray-brown staining of the skin, which sometimes is mistaken for bruising. The affected areas may take the appearance of a hand (if a hand, with lime juice on it, touches the child and transferred the juice to the skin of the child) or there can be driplike marks caused by the juice dripping down the patient's body. Usually the lesions are not regularly spaced and there is a history of exposure to the chemical, which is found in many citrus fruits. Although there are many causes of bruising in children, none of them appear as uniform as in association with coining.
Figure 1.
Competing interests: None declared