Differential Diagnosis for Children with Maculopapular Rash during Fever from Body to Head

Single Most Likely Diagnosis

• Viral Exanthem (e.g., Roseola, Measles, Rubella): These are common viral infections in children that typically present with a maculopapular rash and fever. The rash often spreads from the body to the head.

Other Likely Diagnoses

• Scarlet Fever: Caused by Group A beta-hemolytic streptococci, it presents with a characteristic rash that feels like sandpaper, fever, and other symptoms like a "strawberry tongue."
• Kawasaki Disease: An acute febrile illness of childhood characterized by a maculopapular rash, fever, conjunctivitis, erythema of the lips and oral mucosa, changes in the extremities, and cervical lymphadenopathy.
• Infectious Mononucleosis (Mono): Caused by Epstein-Barr virus, it can present with fever, rash (especially if the patient is given ampicillin), and lymphadenopathy.

Do Not Miss Diagnoses

• Meningococcemia: A severe infection caused by Neisseria meningitidis, which can present with a petechial or purpuric rash, fever, and signs of meningitis or sepsis. It is life-threatening and requires immediate treatment.
• Rocky Mountain Spotted Fever (RMSF): A tick-borne illness caused by Rickettsia rickettsii, characterized by fever, headache, and a maculopapular rash that often starts on the wrists and ankles and spreads to the trunk.
• Toxic Shock Syndrome: A medical emergency caused by bacterial toxins, often presenting with fever, rash, hypotension, and involvement of three or more organ systems.

Rare Diagnoses

• Erythema Infectiosum (Fifth Disease): Caused by Parvovirus B19, it is characterized by a "slapped-cheek" appearance and a maculopapular rash on the body.
• Enteroviral Infections: Certain enteroviruses can cause a maculopapular rash along with fever and other systemic symptoms.
• Juvenile Idiopathic Arthritis (JIA): Some forms of JIA can present with a rash and fever, although this is less common and typically accompanied by joint symptoms.

Each of these diagnoses has distinct features, but the key to diagnosis lies in a thorough history, physical examination, and appropriate laboratory testing. The single most likely diagnosis and other likely diagnoses are based on common presentations in pediatric populations, while the "do not miss" diagnoses are critical due to their potential for severe morbidity or mortality if not promptly recognized and treated. Rare diagnoses, though less common, should be considered when other explanations are ruled out or when specific clues in the history or physical examination suggest their presence.