Which of the following is/are tuberculides – a) Lichen scrofulosorumb) Lichen nichidusc) Lichen aureusd) Erythema nodosum

**Core Concept**
Tuberculides are a group of skin eruptions associated with an underlying **tuberculosis** infection, often occurring in response to the presence of **Mycobacterium tuberculosis** in a person with a strong immune response. They are classified based on their clinical and histopathological features.

**Why the Correct Answer is Right**
The correct answer includes **Lichen scrofulosorum**, which is recognized as a tuberculide, characterized by small, lichenoid papules that occur mainly on the abdomen, chest, back, and extremities in patients with **tuberculosis**.

**Why Each Wrong Option is Incorrect**
**Option C:** **Lichen aureus** is not a tuberculide; it is a type of pigmented purpuric dermatosis.
**Option D:** While **Erythema nodosum** can be associated with various conditions, including infections and **tuberculosis**, it is not classified specifically as a tuberculide.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that tuberculides indicate a strong cell-mediated immune response to **Mycobacterium tuberculosis**, and their presence can be a clue to underlying **tuberculosis**.

**Correct Answer: A. Lichen scrofulosorum**