What is the appropriate evaluation and treatment for a rash on the hands and feet in a patient of unknown age and medical history?

Evaluation and Management of Rash on Hands and Feet

Immediate Priority: Rule Out Life-Threatening Conditions

If the patient has fever, systemic symptoms, or petechial/purpuric lesions on hands and feet, immediately initiate empiric doxycycline (and ceftriaxone if meningococcemia cannot be excluded) without waiting for laboratory confirmation, as Rocky Mountain spotted fever and meningococcemia can be fatal within days if treatment is delayed. 1, 2

Critical Red Flags Requiring Immediate Treatment:

• Petechial or purpuric rash with fever, headache, or altered mental status suggests Rocky Mountain spotted fever or meningococcemia—50% of RMSF deaths occur within 9 days, and absence of tick exposure does not exclude diagnosis (present in only 60% of cases) 1, 2
• Rapidly progressive rash with systemic toxicity (fever, tachycardia, hypotension, confusion) requires immediate hospitalization and empiric antibiotics 1
• Cyanotic extremities with generalized rash in a toddler mandates immediate treatment for potential RMSF or meningococcemia 2

Systematic Diagnostic Approach for Non-Emergent Cases

Key Historical Elements to Obtain:

• Age of patient: Hand-foot-and-mouth disease predominantly affects children under 10 years, while hand eczema is more common in adults 3, 4
• Timing and progression: Vesicular lesions appearing 1-2 days after fever onset suggest hand-foot-and-mouth disease 5
• Associated symptoms: Oral ulcers with hand/foot rash indicate hand-foot-and-mouth disease; pruritus suggests eczema or contact dermatitis 6, 3
• Occupational/environmental exposures: Frequent water exposure, irritants, or allergens point toward hand eczema 6
• Medication history: Recent drug exposure may indicate drug reaction 5
• Tick exposure and outdoor activities: Consider RMSF, especially April-September 1

Physical Examination Specifics:

• Lesion morphology: Vesicular lesions suggest hand-foot-and-mouth disease or eczema; petechiae/purpura indicate serious bacterial infection; target lesions suggest erythema multiforme 5, 1, 3
• Distribution pattern: Hand-foot-and-mouth disease affects palms, soles, and oral mucosa; eczema typically involves dorsal hands and wrists; RMSF begins on wrists/ankles and spreads centrally 5, 1, 3
• Oral involvement: Painful oral ulcers on tongue, gums, and buccal mucosa are characteristic of hand-foot-and-mouth disease 5, 3
• Presence of fever: Fever preceding rash by 1-2 days suggests hand-foot-and-mouth disease; persistent high fever with rash suggests serious infection 5, 3

Most Common Diagnoses by Age and Presentation

In Children (Especially Under 10 Years):

Hand-Foot-and-Mouth Disease is the most likely diagnosis if:

• Low-grade fever (can exceed 102.2°F) precedes rash by 1-2 days 5
• Vesicular lesions on palms, soles, and oral mucosa 5, 3
• Painful oral ulcers that may persist 7-10 days 5, 3
• Occurs spring to fall in North America 3

Management: Supportive care with acetaminophen or ibuprofen for pain; ensure adequate hydration; oral lidocaine is not recommended 3

In Adults or Chronic Cases:

Hand Eczema is most likely if:

• Pruritic, dry, scaly patches on dorsal hands and wrists 6, 4
• History of atopic disease, irritant exposure, or frequent handwashing 6
• Chronic or relapsing course 4

Management Algorithm:

1. Avoid irritants: Use soap substitutes (dispersible cream); avoid prolonged water exposure; wear cotton gloves under protective gloves 6
2. Intensive emollients: Apply after bathing and frequently throughout day 6
3. Topical corticosteroids:
   • Mild (grade 1): 1% hydrocortisone to hands 6
   • Moderate (grade 2): Betnovate, elocon, or dermovate ointment to body; apply for 2-3 weeks then reassess 6
4. If infected (crusting, weeping): Add topical antibiotics (alcohol-free formulations) or oral antibiotics (tetracycline ≥2 weeks) 6

Special Considerations

Paronychia (Nail Fold Inflammation):

• Common with chronic hand eczema or in patients on EGFR tyrosine kinase inhibitors 6
• Keep hands dry; avoid prolonged water exposure 6
• May require topical antibiotics and corticosteroids 6

Elderly Patients with Pruritic Rash:

• Initial treatment: Emollients with high lipid content plus topical steroids for at least 2 weeks to treat asteatotic eczema 6
• If unresponsive: Consider gabapentin; avoid sedating antihistamines due to fall risk 6
• Reassess if no improvement after initial treatment 6

When to Refer to Dermatology:

• Diagnostic uncertainty between serious causes 6, 7
• Chronic grade 2 or higher eczema affecting quality of life 6
• No response to primary care management 6
• Suspected contact dermatitis requiring patch testing 6

Critical Pitfalls to Avoid

• Do not wait for the classic triad of fever, rash, and tick bite in suspected RMSF—it is present in only a minority at initial presentation 1
• Do not exclude serious disease based on absence of rash—up to 20% of RMSF cases lack rash 1
• Do not use oral lidocaine for hand-foot-and-mouth disease pain 3
• Do not prescribe sedating antihistamines to elderly patients due to fall risk 6
• Do not overlook secondary bacterial infection in eczema—look for crusting, weeping, or lack of response to treatment 6