Can scabies occur solely on the feet and lower legs?

Scabies Distribution on the Body

Yes, scabies can occur solely on the feet and lower legs, although this is not the typical distribution pattern in adults and older children.

Typical Distribution Patterns

Scabies typically presents with different distribution patterns based on age:

• Adults and older children: Primarily affects:

  • Interdigital web spaces of hands
  • Flexor aspects of wrists
  • Axillae
  • Elbows
  • Waist
  • Buttocks
  • Genitalia 1

• Infants and very young children: Commonly involves:

  • Palms and soles
  • Head and scalp
  • More widespread distribution 1, 2

Atypical Presentations

While the feet and lower legs are not the most common sites for scabies in adults, several factors can lead to this atypical presentation:

• Prolonged untreated infestation: In hot tropical climates, long-standing scabies can produce severe infestation with involvement of palms and soles in older children and adults 2

• Immunocompromised status: Patients with immune deficiencies may present with atypical distributions 3

• Variant forms: Crusted scabies (Norwegian scabies) can present with different distribution patterns and may not follow typical patterns 4

Diagnostic Considerations

When evaluating potential scabies limited to feet and lower legs, consider:

1. Key clinical features:

   • Intense nocturnal itching (pathognomonic)
   • Pruritus out of proportion to visible lesions
   • Close contacts also experiencing itching 4

2. Pathognomonic signs:

   • Burrows (up to 1 cm in length)
   • Erythematous papules with excoriation 4

3. Differential diagnosis:

   • Tinea pedis (athlete's foot)
   • Contact dermatitis
   • Eczema
   • Other parasitic infestations

Confirmation of Diagnosis

Definitive diagnosis can be made by:

• Microscopic examination of skin scrapings to identify mites, eggs, or fecal pellets 1
• Dermatoscopy to visualize burrows and mites

Treatment Approach

If scabies is confirmed, even with atypical distribution:

1. First-line treatment:

   • Permethrin 5% cream applied from head to soles of feet for 8-14 hours 5, 6
   • Despite atypical distribution, treat the entire body as mites may be present in non-symptomatic areas

2. Alternative treatments:

   • Oral ivermectin (200 μg/kg) repeated after 14 days 5
   • Sulfur 6% ointment applied nightly for 3 nights 5

3. Environmental measures:

   • Machine wash bedding and clothing using hot cycle
   • Dry clean items that cannot be washed
   • Remove items from body contact for at least 72 hours 5

4. Treatment of contacts:

   • Treat all household members and close contacts simultaneously, even if asymptomatic 5

Follow-up

• Evaluate after 1 week to assess treatment response
• Persistent pruritus may continue for several weeks after successful treatment and is not an indication for retreatment
• Retreatment is indicated only if live mites are still present after 14 days 5, 6

Important Caveat

While scabies can present solely on the feet and lower legs, especially in certain circumstances, this atypical presentation should prompt thorough evaluation to rule out other conditions and ensure appropriate treatment.