Norwegian (crusted) scabies differs from classical scabies in that it occurs predominantly in immunocompromised patients. Which of the following best explains its distinctive clinical appearance?
- A Lack of cell-mediated immune response allows uncontrolled mite multiplication (thousands to millions of mites), producing hyperkeratotic plaques with minimal itch ✓
- B Severe itch due to massive IgE response to mite antigens
- C Superinfection with Staphylococcus aureus causing impetigo
- D Mite burrowing deeper into dermis rather than stratum corneum
Correct answer: A. Lack of cell-mediated immune response allows uncontrolled mite multiplication (thousands to millions of mites), producing hyperkeratotic plaques with minimal itch
Explanation
In Norwegian (crusted) scabies, defective cell-mediated immunity (HIV/AIDS, HTLV-1 infection, Down syndrome, organ transplant recipients) prevents the normal host response that limits infestation to ~10–15 mites in classic scabies. Thousands to millions of mites proliferate in thick hyperkeratotic scaling plaques, particularly on hands, feet, scalp, and nails. Paradoxically, itching is minimal or absent. The condition is highly contagious (institutional outbreaks). Oral ivermectin combined with topical permethrin or keratolytics is required.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.