Final answer:
The child with a red 'slapped cheek' appearance and a pink macular rash likely has Fifth disease, caused by parvovirus B19. It shares cold-like symptoms with Roseola but is differentiated by the characteristic facial rash and causative virus.
Step-by-step explanation:
If a child presents with a red face, described as a slapped cheek appearance and a lacy, pink macular rash on the torso, it is likely that the child has Fifth disease, also known as erythema infectiosum. Fifth disease is caused by the parvovirus B19 and is more common in children than adults. Early symptoms of this infection include headache, fever, and upset stomach, similar to cold-like symptoms. After these initial signs, the characteristic 'slapped cheek' rash appears on the face, followed by a secondary rash on the arms, legs, chest, back, or buttocks, which can come and go over several weeks.
Roseola and Fifth disease have similarities in that they both have initial cold-like symptoms and rashes as a common presentation, but they differ in the type of rash and the virus that causes them. Roseola usually comes with a high fever followed by a rash that starts on the trunk and might spread outward, caused by human herpesvirus-6 (HHV-6) or HHV-7. In contrast, Fifth disease begins with a 'slapped cheek' rash caused by parvovirus B19.