Does this young girl have the same rash as her mother?

Joe Monroe practices at the Dawkins Dermatology Clinic, Oklahoma City, and is the department editor for Dermatology Digest. The author has indicated no relationships to disclose relating to the content of this article.


CASE


A 30-year-old mother and her 8-year-old daughter presented with rashes on their arms and hands (Figure 1). The mother had longstanding, poorly controlled psoriasis vulgaris, but now she had a new and even bigger problem: a rash developed on her daughter that the child had never had before. Both Mom and the child's pediatrician were puzzled about the cause of the child's new rash, which had begun almost 3 months ago and was now so florid as to be alarming. The girl's rash first appeared within 2 weeks after resolution of a streptococcal throat infection. The rash was itchy and getting worse by the day. The child had also gotten a new kitten from the animal shelter shortly before this had all begun. Top­ical clotrimazole was of no help. The mother was worried about a possible diagnosis of psoriasis but noted that the child's rash looked completely different from her own.


Physical examination The child's rash was composed of discrete pinkish-orange round scaly papules, nodules, and plaques. These were most dense on the child's face, but a great number were also on her arms, trunk, and legs. Ranging in size from pinpoint to 2 cm, the lesions averaged about 1 cm and were uniformly covered with a loose white scale on a salmon-pink base. KOH (potassium hydroxide) test was negative. There was no involvement of the child's elbows, knees, scalp, or nails.