Toddler with Widespread Itchy Papules: Scabies Versus Eczema in a Crowded Household
A 2-year-old boy is brought in with a 3-week history of intensely itchy papules on the trunk, extremities, and genital area. He attends daycare, and two other children in his class have had 'itchy bumps.' His mother reports similar itching for 2 weeks, worse at night. On exam, there are excoriated papules and burrows in the web spaces of the fingers, wrists, and axillae, plus several 2-3 mm nodules on the scrotum. The mother has a similar rash on her wrists. The family lives in a two-bedroom apartment with the parents, the toddler, and a 6-month-old infant. The toddler has mild atopic dermatitis treated with topical hydrocortisone. The family has limited transportation and one car.
1. What is the diagnosis, and how does the presence of genital nodules and the infant sibling change management?
Read the worked answer
The diagnosis is scabies, supported by:
- Intense nocturnal pruritus in the patient and mother.
- Burrows in web spaces, wrists, and axillae - classic sites.
- Household and daycare clustering of itchy lesions.
- Genital nodules in a toddler: these are likely scabietic nodules (a hypersensitivity reaction), not a sexually transmitted process; they are common in infants and young children and do not by themselves imply abuse.
Management implications:
- Treat the entire household simultaneously, including the 6-month-old infant and both parents, even if asymptomatic (asymptomatic carriers can transmit).
- Infant < 2 months or < 10 kg: permethrin 5% is generally not recommended under 2 months; precipitated sulfur 5-10% in petrolatum or crotamiton may be used, with guidance from pediatric dermatology. For a 6-month-old, permethrin 5% is commonly used off-label or per local formulary; confirm weight and age thresholds.
- Toddler: permethrin 5% cream applied neck-down (including under nails), left on 8-14 hours, repeated in 7 days. Treat the scalp and face in infants.
- Environment: wash bedding and clothing in hot water and dry on high heat; items that cannot be washed can be sealed in a bag for 72 hours. Vacuum.
- Daycare: inform the daycare so other affected children and staff can be evaluated; the child can return after the first treatment.
- Pruritus and nodules may persist for weeks after successful treatment (post-scabietic itch/nodules); treat with emollients and topical steroids, and do not re-treat unless new burrows appear.
Transportation constraints: arrange a single trip to a pharmacy for all household members' medication to ensure simultaneous treatment.
2. Two weeks after treatment, the toddler still itches and the mother is convinced the treatment failed. How do you distinguish treatment failure from post-scabietic pruritus, and what do you do?
Read the worked answer
Distinguish by exam and history, not itch alone:
Suggests treatment failure/reinfestation:
- New burrows or new papules in classic sites.
- New cases in household members who were treated.
- Inadequate application (missed areas, not repeated at 7 days, not treating all contacts, not washing bedding).
- Re-exposure at daycare or from an untreated contact.
Suggests post-scabietic pruritus:
- Itch persists but no new burrows; old lesions are healing.
- Nodules may persist for weeks to months.
- Itch improves gradually over 2-4 weeks.
Management:
- Re-examine for burrows, especially web spaces, wrists, and genitalia; consider dermoscopy if available.
- If no new burrows and all contacts treated, reassure and treat symptomatically: emollients, topical corticosteroid for nodules and itch, and oral antihistamine at night if needed.
- If new burrows or untreated contacts, re-treat the patient and all household members simultaneously, and verify application technique and environmental measures.
- Do not repeatedly re-treat without evidence of active infestation, as this increases irritation and resistance concerns.
- Document the plan and set expectations that itch can last 2-4 weeks.
Given the family's limited transportation, provide written instructions and a single follow-up plan.