What is the cause and treatment of solid red round spots all over a 5-year-old's body?

Differential Diagnosis and Immediate Management of Solid Red Round Spots in a 5-Year-Old

The most critical immediate consideration is Rocky Mountain Spotted Fever (RMSF) or other tickborne rickettsial diseases, which can be fatal within 9 days if untreated—start doxycycline immediately if there is ANY suspicion based on fever, headache, and rash, even without a reported tick bite. 1, 2

Life-Threatening Conditions to Rule Out First

Rocky Mountain Spotted Fever (RMSF)

• RMSF presents with fever (often >105°F), headache, and a maculopapular rash that classically begins on wrists, ankles, and forearms, then spreads centrally, including palms and soles. 1, 2
• Up to 40% of RMSF patients report NO tick bite history, so absence of tick exposure should NOT exclude this diagnosis. 1, 2
• 50% of RMSF deaths occur within 9 days of illness onset. 2
• Peak season is April-September, but can occur year-round. 2
• If suspected, obtain CBC (expect thrombocytopenia), comprehensive metabolic panel, blood cultures, and acute serum for IgG/IgM antibodies to R. rickettsii, but DO NOT wait for results—start doxycycline immediately. 1, 2

Meningococcemia

• Cannot be reliably distinguished from tickborne diseases on clinical grounds alone. 2
• Consider administering intramuscular ceftriaxone pending blood cultures because of this diagnostic overlap. 2

Common Infectious Causes

Roseola (Exantema Súbito)

• Caused by Human Herpesvirus 6 (HHV-6B) or HHV-7, characterized by high fever for 3-5 days followed by rash AFTER fever resolution. 3, 4
• The rash consists of rose-pink macules or maculopapules that appear on the trunk and spread peripherally. 3, 4
• Approximately 90% of children are infected by age 1 year. 3
• Diagnosis can be confirmed with PCR for viral DNA or IgM serology, though clinical diagnosis is usually sufficient. 3
• Treatment is supportive in immunocompetent children; antivirals (ganciclovir or foscarnet) are reserved for immunocompromised patients with severe disease. 3

Viral Exanthems (Enterovirus, Fifth Disease)

• Enteroviral infections can cause fever and rash, including palms and soles involvement. 2, 4
• Erythema infectiosum (fifth disease) is characterized by a viral prodrome followed by the "slapped cheek" facial rash. 4

Scarlet Fever

• Rash develops on upper trunk, then spreads throughout the body, SPARING palms and soles. 1, 4
• Associated with sore throat, strawberry tongue, and sandpaper-textured rash. 4

Dermatologic Emergencies

Eczema Herpeticum

• Presents with multiple uniform "punched-out" erosions or vesiculopustular eruptions that are very similar in shape and size. 2
• May progress rapidly to systemic infection without antiviral therapy. 2
• Start systemic acyclovir immediately if suspected, and add empirical antibiotics for secondary bacterial infection. 2

Staphylococcal Scalded Skin Syndrome (SSSS)

• Requires immediate recognition and treatment to avoid considerable morbidity and mortality. 5

Non-Infectious Causes

Urticaria Pigmentosa (Cutaneous Mastocytosis)

• Red to brown to yellow lesions measuring a few mm to 1-2 cm, presenting as multiple macules, plaques, or nodules. 1
• Positive Darier's sign (wheal and flare formation after stroking lesions). 1
• Lesions typically appear by 6 months of age in 80% of cases. 1
• Most cases resolve by age 10. 1

Atopic Dermatitis

• Requires personal or family history of atopy plus dry skin and visible eczema; pruritus is mandatory. 2, 4

Critical History Elements to Obtain

• Fever, headache, chills, myalgias, nausea/vomiting 1, 2
• Recent outdoor activities, camping, hiking, or playing in brushy areas 1, 2
• Tick exposure or pet exposure 1, 2
• Geographic location and season 1, 2
• Medication history 1, 2
• Timing of rash relative to fever onset 3, 4

Physical Examination Priorities

• Check for rash on palms and soles 1, 2
• Assess for petechiae 2
• Look for uniform "punched-out" lesions 2
• Examine scalp, axillae, groin for attached ticks 2
• Evaluate for conjunctival injection and altered mental status 2
• Test for Darier's sign (stroke lesions to see if they wheal) 1

Immediate Management Algorithm

1. If fever + headache + rash (especially with palms/soles involvement): Start doxycycline immediately for presumed RMSF without waiting for laboratory confirmation. 1, 2
2. Consider intramuscular ceftriaxone to cover meningococcemia pending cultures. 2
3. If uniform "punched-out" lesions: Start systemic acyclovir immediately for presumed eczema herpeticum. 2
4. If rash appears AFTER fever resolution: Likely roseola; supportive care only. 3, 4
5. If positive Darier's sign: Likely urticaria pigmentosa; supportive care with antihistamines. 1

Critical Pitfalls to Avoid

• Never exclude RMSF based on absence of tick bite history or geographic location. 1, 2
• Never wait for serologic confirmation before starting treatment for suspected RMSF—serology is negative in first week. 2
• Never dismiss a rapidly evolving rash as "just eczema" without ruling out eczema herpeticum. 2
• Normal WBC count does NOT exclude RMSF; thrombocytopenia is more specific but may not be present early. 1