Which of the following is the MOST common tumour of lower eyelid?
**Core Concept**
The question is testing the student's knowledge of the common tumors affecting the lower eyelid. The lower eyelid is a common site for various types of tumors, including benign and malignant lesions. **Basal cell carcinoma** is a type of skin cancer that commonly affects the face, including the lower eyelid.
**Why the Correct Answer is Right**
Basal cell carcinoma is the most common type of skin cancer and accounts for approximately 80% of all skin cancers. It arises from the basal cell layer of the epidermis and is often caused by exposure to ultraviolet (UV) radiation from the sun or tanning beds. The tumor grows slowly and locally, but if left untreated, it can invade surrounding tissues and cause significant damage.
**Why Each Wrong Option is Incorrect**
**Option A:** **Sebaceous gland carcinoma** is a rare type of skin cancer that originates from the sebaceous glands. While it can affect the eyelids, it is much less common than basal cell carcinoma.
**Option B:** **Melanoma** is a type of skin cancer that arises from melanocytes. Although it is more aggressive than basal cell carcinoma, it is less common on the lower eyelid.
**Option C:** **Benign mixed tumor** is a type of tumor that can occur in the salivary glands, but it is not typically associated with the lower eyelid.
**Clinical Pearl / High-Yield Fact**
The "ABCDE" rule is a useful mnemonic for evaluating suspicious skin lesions: Asymmetry, Border, Color, Diameter, and Evolving. This can help identify potential skin cancers, including basal cell carcinoma.
**Correct Answer:** C. Benign mixed tumor is not more likely to occur in lower eyelid.