Commonest tumor of lid is
**Core Concept**
The question is testing the student's knowledge of the common ocular tumors, specifically those affecting the eyelid. The eyelid is a common site for various types of tumors, ranging from benign to malignant. Understanding the epidemiology and clinical presentation of these tumors is crucial for ophthalmologists and dermatologists.
**Why the Correct Answer is Right**
The correct answer is **Basal cell carcinoma**. This is the most common type of eyelid tumor, accounting for approximately 80% of all eyelid cancers. Basal cell carcinoma arises from the basal cell layer of the epithelium and is thought to result from chronic sun exposure, leading to DNA damage and uncontrolled cell growth. The tumor grows slowly and locally, but can invade surrounding tissues if left untreated.
**Why Each Wrong Option is Incorrect**
* **Option A:** Squamous cell carcinoma is a less common type of eyelid tumor, accounting for approximately 10-15% of cases. While it can be aggressive, it is not the most common type of eyelid cancer.
* **Option B:** Sebaceous gland carcinoma is a rare but aggressive type of eyelid tumor that arises from the sebaceous glands. It is not the most common type of eyelid cancer.
* **Option D:** Melanoma is a rare type of eyelid tumor that arises from the melanocytes. While it is a serious condition, it is not the most common type of eyelid cancer.
**Clinical Pearl / High-Yield Fact**
The ABCDE rule can help differentiate benign from malignant eyelid lesions: Asymmetry, Border irregularity, Color variation, Diameter greater than 6mm, and Evolving characteristics.
**Correct Answer:** A. Basal cell carcinoma