What is the diagnosis and treatment for a patient with a red raised rash that feels like sandpaper?

Diagnosis: Scarlet Fever

A red raised rash that feels like sandpaper is the classic presentation of scarlet fever, caused by Group A Streptococcus (Streptococcus pyogenes), and requires immediate treatment with penicillin or amoxicillin to prevent serious complications including rheumatic fever, glomerulonephritis, and invasive streptococcal disease. 1, 2

Clinical Presentation

The sandpaper-textured rash is pathognomonic for scarlet fever and typically presents with:

• Characteristic sandpaper-like, papular exanthem that is rough to touch, distinguishing it from other viral exanthems 1, 2
• Associated symptoms: Fever, sore throat (tonsillopharyngitis), and the distinctive rash usually appearing in children aged 5-15 years 2
• Typical distribution: The rash usually begins on the trunk and spreads peripherally, though atypical presentations can occur with involvement limited to extremities 3
• Additional features: Strawberry tongue, circumoral pallor, and Pastia's lines (accentuation in skin folds) may be present 2

Critical Diagnostic Considerations

Early recognition is crucial because delayed diagnosis can lead to fatal outcomes, particularly when scarlet fever complicates cellulitis or other skin infections. 4

• The sandpaper texture is the key distinguishing feature from other febrile rashes 1, 2
• Do not mistake this for a drug eruption, especially if antibiotics were recently started for another infection—this diagnostic error can be fatal 4
• In adults or atypical presentations, maintain high clinical suspicion even with unusual rash distribution 3
• Throat culture or rapid strep test confirms Group A Streptococcus, but treatment should not be delayed while awaiting results 2

Immediate Treatment Protocol

Prescribe antibiotics immediately upon clinical diagnosis to reduce complications and prevent spread: 1, 2

First-Line Treatment:

• Phenoxymethylpenicillin (Penicillin V): Standard first-line therapy 1
• Amoxicillin 500 mg three times daily for 7-10 days: Alternative penicillin option 5

Penicillin-Allergic Patients:

• Cephalosporins (if no severe penicillin allergy) 5
• Macrolides (azithromycin) as alternative, though resistance patterns should be considered 1

Potential Complications if Untreated

Failure to treat promptly can result in: 2, 4

• Acute rheumatic fever
• Post-streptococcal glomerulonephritis
• Bacteremia and sepsis
• Pneumonia
• Endocarditis
• Meningitis
• Toxic shock syndrome (particularly when complicating cellulitis or wound infections) 4

Common Pitfalls to Avoid

• Do not dismiss as viral exanthem or drug reaction without considering scarlet fever, especially in the presence of the characteristic sandpaper texture 4
• Do not delay treatment waiting for culture confirmation—the clinical diagnosis based on sandpaper rash and associated symptoms is sufficient to initiate therapy 1, 2
• Do not underestimate severity in adults—while primarily pediatric, adult cases can present atypically and progress to severe complications 3, 4
• Recognize that scarlet fever can complicate existing skin infections (cellulitis, burns, wounds), making diagnosis more challenging but treatment even more urgent 2, 4

Infection Control

• Isolate patient to prevent spread in crowded settings (schools, daycare) 2
• Disease is transmitted through direct contact with saliva and nasal secretions 2
• Patient becomes non-contagious 24 hours after starting appropriate antibiotic therapy 1