Pediatric rash post-illness

Over the last six months, each time my ten year old son has had a respiratory illness (including a cold, bronchitis, and a sinus infection, all diagnosed as viral, all febrile), he has broken out in a rash during the second day of his illness.  They are not associated with any particular medication that he has been administered, because he has received a different medication during each visit to the pediatrician.  The lesions are absolutely flat, not raised, and are not scaly in any way. They don't seem to resemble the pictures of post-strep guttate psoriasis that I have seen.  They are distributed over his torso and upper legs, and are 2-3 mm in diameter. They have not previously caused him discomfort, but today he has extreme pruritis and is very uncomfortable.  His pediatrician just shakes his head.  I should mention that he has eczema, his dad has psoriasis, and he has allergies/asthma.  Any ideas what we are looking at?

[Alan Rockoff, MD]

Viruses often cause nondescript rashes like the ones you describe.  I can't ascribe much significance to the fact that it's happened a bunch of times.  If you take photos and show a dermatologist, it's possible that he or she would be able to offer a suggestion,but I doubt it.

Take care.

Dr. Rockoff