A 20-year-old man is advised to use permethrin cream for an itchy rash between the fingers; what is the diagnosis?

A 20-year-old man is advised to use permethrin cream for an itchy rash between the fingers; what is the diagnosis?

• A. Ringworm
• B. Scabies
• C. Contact dermatitis
• D. Psoriasis

Answer: (B)

Interdigital itching with a rash in the finger webs is a classic sign of scabies, caused by a mite infestation that often wakes patients with intense nighttime itching. Permethrin cream is the first-line treatment for scabies because it kills the mites and their eggs (it’s a topical scabicide). The usual approach is to apply it to the entire body from neck down and leave it on for about 8–14 hours before washing off. Because scabies spreads easily through close contact, household or close contacts should be treated at the same time to prevent reinfestation. Other conditions present differently. Ringworm (a fungal infection) tends to show ring-shaped, expanding lesions with a clear center and a scaly border, and is treated with antifungals. Contact dermatitis is a non-mite rash caused by an irritant or allergen, often localized to the area of contact and managed with avoidance and topical steroids. Psoriasis shows well-defined plaques with silvery scales, not an interdigitating mite infestation.

Interdigital itching with a rash in the finger webs is a classic sign of scabies, caused by a mite infestation that often wakes patients with intense nighttime itching. Permethrin cream is the first-line treatment for scabies because it kills the mites and their eggs (it’s a topical scabicide). The usual approach is to apply it to the entire body from neck down and leave it on for about 8–14 hours before washing off. Because scabies spreads easily through close contact, household or close contacts should be treated at the same time to prevent reinfestation.

Other conditions present differently. Ringworm (a fungal infection) tends to show ring-shaped, expanding lesions with a clear center and a scaly border, and is treated with antifungals. Contact dermatitis is a non-mite rash caused by an irritant or allergen, often localized to the area of contact and managed with avoidance and topical steroids. Psoriasis shows well-defined plaques with silvery scales, not an interdigitating mite infestation.