Viral Exanthem: This is a common condition characterized by a widespread rash, often appearing as macules, and can be caused by various viruses such as enteroviruses, adenoviruses, or parvovirus B19. The absence of pruritus and systemic symptoms, along with the distribution of the rash, supports this diagnosis.

Pityriasis Rosea: Although it typically starts with a herald patch, the subsequent rash can appear as macules and spread over the body, sparing the head. The lack of pruritus is consistent with this condition.
Drug Eruption: A drug-induced rash can present with macules and vary in distribution. The absence of systemic symptoms does not rule out this possibility, especially if the patient has recently started a new medication.
Secondary Syphilis: This condition can cause a rash that appears as macules, often involving the trunk and extremities but sparing the head. However, it usually accompanies other systemic symptoms, which are absent in this case.

Meningococcemia: Although rare, this condition can present with a petechial or macular rash and is life-threatening. The absence of systemic symptoms early in the disease does not rule out this diagnosis, and it is crucial to consider it due to its high mortality rate if untreated.
Disseminated Gonococcal Infection: This can cause a rash that may appear as macules, along with systemic symptoms, but early in the disease, the rash may be the only symptom.

Erythema Multiforme: This condition is characterized by target lesions but can sometimes appear as macules. It is often associated with herpes simplex virus infections or drug reactions.
Kawasaki Disease: Although it primarily affects children, it can cause a rash that may appear as macules, along with other systemic symptoms such as fever, which are not present in this case.
Leptospirosis: A zoonotic infection that can cause a rash among other systemic symptoms. The rash may appear as macules, but the disease is more commonly associated with exposure to contaminated water.