10th August 2020

A 30-year-old lady is 32 weeks pregnant. She is seen in clinic due to a rash that has developed rapidly

A 30-year-old lady is 32 weeks pregnant. She is seen in clinic due to a rash that has developed rapidly in the flexure of her right arm. On examination, there is a round annular plaque, with a ring-like appearance. It is erythematous throughout with small white pustules around the edge. She has a similar lesion further down her arm that appears to have crusted. This is her second pregnancy and she has no past medical history of note. She has no lesions anywhere else, including in her mouth. 

Which of the following is the most likely cause? 

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