Patterned bruises on 2 infants

The Case

You are called to the emergency department to evaluate a 4-month-old girl with multiple areas of purpura, including a distinctive bruise on the lateral aspect of the left thigh (Figure 1). The child’s mother states that she noticed these lesions after picking up the infant from her biologic father, who was watching the child alone. No trauma history is reported. The child has been otherwise in good health, with no signs of infection.

Diagnosis:

Adult human bites

The pattern of bruising on the child is characteristic of an adult human bite. The upper (maxillary) arch is larger than the lower arch, and the overall width of the maxillary arch is typically between 3 cm and 4 cm.

Inside the upper arch, there are 3 linear bruises parallel to the tooth imprint bruises. The central linear bruise is caused by shear stress on the capillaries because the victim’s skin is crimped between the perpetrator’s maxillary teeth and tongue. The lateral linear bruises may be because of the same shear stress mechanism, although they could also be because of positive pressure from the inner ridge of the perpetrator’s upper molars.¹

A similar pattern of bruising can be seen on the shin of an infant girl who died of abusive head trauma  (Figure 2). The perpetrator, her mother, was a petite adult, so the shape of the bite is more similar to a child-inflicted injury. The outer, darker, round bruise is caused by positive pressure from the perpetrator’s teeth, whereas both inner, brighter, somewhat linear bruises are because of shear stress.

This shear stress mechanism of bruising has been reported as vertical linear bruises along an apparent strain line where the buttocks arch into the gluteal cleft.² The bruises appear to result from compressing/shearing forces arising during abusive spanking (Figure 3). The horizontal pattern of bruising also corresponds to areas of shear strain of the skin at the margins of the perpetrator’s fingers and the hydrostatic force of blood compressed outward from beneath the fingers.

Another site of crimping strain seen in abusive injury is along the top margin of the helix during a hand slap to the face and ear (Figure 4).

When an adult human bite is suspected, in addition to documenting the pattern, size, and color of the lesion, the physician should 1) obtain high-quality photographs, 2) attempt to recover the perpetrator’s DNA from the bite site by the double-swab technique, and 3) obtain a polyvinyl siloxane impression from every bite mark that shows indentation to provide a 3-dimensional model of the bite mark.¹ If the pediatrician is not familiar with these procedures, a forensic odontologist or a child abuse physician should be consulted.

The first child’s injury was wet and dry swabbed for salivary DNA evidence and photographed with a standard American Board of Forensic Odontology #2 scale measurement device. During subsequent questioning by law enforcement, the biologic father disclosed that he had bitten his daughter the night before. He reported doing this because he was frustrated by the infant’s crying and “wanted her to shut up.”

It is critical for medical providers to recognize an inflicted adult bite as a sentinel injury.^3,4 If protective measures for the bite victim are not rapidly implemented, the child has a high likelihood of sustaining additional injuries such as maiming or fatal abusive head trauma.  

REFERENCES

1. Kellogg N; American Academy of Pediatrics Committee on Child Abuse and Neglect. Oral and dental aspects of child abuse and neglect. Pediatrics. 2005;116(6):1565-1568.

2. Feldman KW. Patterned abusive bruises of the buttocks and the pinnae. Pediatrics. 1992;90(4):633-636.

3. Sheets L, Leach M, Nugent, M, Simpson P. Sentinel injuries precede abusive head trauma in infants. Annual Meeting of the Ray Helfer Society. Tucson, AZ; 2008.

4. Petska HW, Sheets LK, Knox BL. Facial bruising as a precursor to abusive head trauma. Clin Pediatr (Phila). 2013;52(1):86-88.