Question

An $8$-day-old newborn is evaluated in the pediatric clinic for a routine well-child visit. The mother is concerned about a skin eruption that appeared on the infant's face three days ago, which seemed to worsen after they sat in a sunlit room. The infant was born at $39$ weeks gestation via an uncomplicated vaginal delivery and is exclusively breastfeeding well. The mother is a $28$-year-old primigravida who has a history of episodic joint stiffness and cold-induced finger discoloration, for which she has not sought medical care. The infant's vital signs include a temperature of $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure of $65/40 \text{ mmHg}$, respiratory rate of $36/\text{min}$, and a heart rate of $72/\text{min}$. Physical examination of the infant reveals erythematous, annular plaques with slightly raised and scaly borders concentrated around the periorbital regions and scalp. The anterior fontanelle is flat and soft, and the lungs are clear to auscultation. Which of the following is the most appropriate next step in the management of this patient?