Commonest site of a rodent ulcer is
**Core Concept**
A rodent ulcer, also known as a basal cell carcinoma (BCC), is a type of skin cancer that arises from the basal cell layer of the epidermis. It is one of the most common forms of skin cancer, particularly in fair-skinned individuals.
**Why the Correct Answer is Right**
The commonest site of a rodent ulcer is the sun-exposed areas of the face, particularly the lower lip, nose, and cheeks. This is due to the cumulative effect of ultraviolet (UV) radiation from the sun, which damages the DNA of skin cells and leads to the development of BCC. The UV radiation causes genetic mutations in the basal cell layer, resulting in the uncontrolled growth of cancer cells. The face is a common site for BCC due to its exposure to the sun.
**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect as BCC is not commonly found in the scalp, although it can occur.
**Option B:** This is incorrect as BCC is not commonly found in the genital area, although it can occur in areas with significant sun exposure.
**Option C:** This is incorrect as BCC is not commonly found in the hands, although it can occur in areas with significant sun exposure.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that BCC is the most common form of skin cancer and can be prevented by protecting the skin from UV radiation through the use of sunscreens, hats, and protective clothing.
**Correct Answer: A. Face.**