3rd July 2023

You are working as an F2 in a GP surgery, and you are asked to review a 17-year-old boy who has come in due to concerns of a new rash

You are working as an F2 in a GP surgery, and you are asked to review a 17-year-old boy who has come in due to concerns of a new rash. He has been unwell for the last 3 days with coryzal symptoms, including a headache, fevers, and some joint pain. His girlfriend noticed a red patch on his back approximately 3cm in diameter (see image). There are no other skin changes of note.

He has a background of acne vulgaris and has been on oral treatment, although he cannot remember the medication name. He is currently not using anything for his skin.

Observation of patient

Based on the history and examination, you suspect the skin change is a herald patch, as seen in pityriasis rosea.

What is the most likely cause?

Select the SINGLE most appropriate option from the list below. Select ONE option only.