ABSTRACT
A 15-year-old girl had disclosed being sexually assaulted 2 weeks ago. She did not seek medical care at that time but was now concerned about possible pregnancy and sexually transmitted infections. During your evaluation, you noted that her external genitalia and anus appeared normal and there was no sign of discharge or infection. She revealed this lesion on her arm (Image 79a). She began her menses at age 13 years, her last period was 3 weeks previously, and her medical history was otherwise negative.
What are the possible causes for this finding?
What is the best way to determine the aetiology of this finding?
https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429170423/e1d751c1-a9c7-4bb9-9d59-53742c84031a/content/fig79a.jpg"/> 178 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429170423/e1d751c1-a9c7-4bb9-9d59-53742c84031a/content/fig79b.jpg"/>This teen has an oval, patterned lesion on her anterolateral right arm with areas of central hypopigmentation, peripheral hyperpigmentation and scaling skin and some granulation tissue. No active cellulitis or vesicles are present. This could be caused by a healing burn, impetigo, atopic dermatitis, chemical contact reaction or trauma. 1
Given the healing nature of the lesion, determining the aetiology by observation or laboratory assessment is problematic. The shape is suggestive of a pattern and the best way to determine its aetiology, at this point, would be to ask the teenager or her parents if they know how it occurred. When asked directly, the teen responds: ‘He bit me there when he was having sex with me’. While specific teeth marks are not visible, the shape and healing nature of the lesion are consistent with that disclosure. A similarly shaped, but more recent bite mark on a young child is also shown (Image 79b). Bite marks have been commonly noted in association with sexual assault and practices have been developed for evaluation and evidence collection. 2
