Question

A child has multiple itchy papular lesions on the genitalia and fingers. Similar lesions are also seen in the younger brother. Which of the following is the most possible diagnosis?

• A. Papular urticaria
• B. Scabies
• C. Atopic dermatitis
• D. Allergic contact dermatitis

Hint:

Finger webs plus genitalia plus a sick sibling points to a contagious mite infection.

Answer 1

The Correct Option is B

The clue that decides this question is the pattern of spread: not just one child, but a sibling in the same house showing the same itchy lesions at the same sites.

1. Papular urticaria: Caused by an allergic response to insect bites, usually seen on the arms and legs. It does not pass from one child to another, so it does not fit here.
2. Scabies: Caused by the mite Sarcoptes scabiei, which burrows into finger webs and genital skin and spreads by skin to skin contact. Because it is contagious within a household, siblings sharing a bed often fall ill together. This matches both the site and the family spread.
3. Atopic dermatitis: A long term allergic skin condition affecting the flexures and face. It is not contagious between siblings, so a brother catching it at the same time makes no sense.
4. Allergic contact dermatitis: Needs direct contact with an irritant or allergen at the site of the rash. There is no shared exposure described that would explain identical lesions in two children.

The correct answer is scabies, since it uniquely explains both the site pattern and the spread to the younger brother.

Let's summarize:

• Finger webs and genitalia are classic scabies sites.
• Household spread to a sibling is a hallmark of scabies, not of allergic skin conditions.

So the most possible diagnosis is scabies.