Pityriasis rosea

• “Pityriasis” means “scaly”
• “rosea” means “pink,”  – but the rashes may look red, gray, brown or purple.

• Self-limiting rash
• Duration: Resolves in about 6–10 weeks
• Characteristic Features:
  • Large circular or oval “herald patch” on the chest, abdomen, or back
  • Occurs in teenagers and young adults (10–35 years)
  • Slightly more common in women
  • Incidence: 0.5% to 2%
  • More common in winter

Possible Causes:

• Viral Infections:
  • Herpesviruses 6 and 7 (HHV-6/7) have the strongest known association
  • Studies are not confirmatory
• Drug-Induced Reactions:
  • Metronidazole
  • Isotretinoin
  • Clozapine
  • Clonidine
• Vaccines:
  • Bacillus Calmette-Guerin (BCG)
  • H1N1
  • Diphtheria
  • Smallpox
  • Hepatitis B
  • Pneumococcus
  • COVID-19

Stages of Development:

1. Initial Symptoms: Fever, headache, or upper respiratory infection
2. Herald Patch:
   • Raised, discolored, circular or oval-shaped patch (1–6 cm)
   • Known as the “herald” or “mother” patch
3. Daughter Patches:
   • Appear 1–2 weeks later
   • Smaller, discolored circular or oval-shaped patches (1–2 cm)
   • Resemble sagging Christmas tree branches
4. Additional Characteristics:
   • Approximately 50% experience itching
   • In darker-skinned or Black people, patches may be more raised (papular) and necrotic in the centers
   • Patches do not cause pain

Treatment:

General Measures:

• Self-Limiting Disease:
  • Control pruritus (may be severe in 25% of patients)
  • Provide education and reassurance
• Moisturising Creams: Apply to dry skin
• Bathing/Showering:
  • Use plain water and bath oil, aqueous cream, or soap substitute
• Sunlight Exposure: Cautiously expose skin to sunlight without burning

Specific Measures:

• Topical Treatments:
  • Medium potency topical steroid creams/ointments
• Oral Antihistamines: May reduce itch while waiting for rash to resolve
• For Severe Itching:
  • Zinc oxide
  • Oral steroids (routine use not recommended due to risk of relapse and limited evidence)
  • A 7-day course of aciclovir may speed lesion resolution and relieve severe itching
• Persistent or Extensive Cases:
  • Phototherapy (narrowband ultraviolet B therapy)

Notes:

• The rash is self-limiting and generally resolves without specific treatment.
• General measures focus on symptomatic relief and preventing further irritation.
• Specific treatments are used for severe cases or when general measures are insufficient.