The commonest clinical pattern of basal cell carcinoma is
**Core Concept**
Basal cell carcinoma (BCC) is a type of skin cancer that originates from the basal cell layer of the epidermis. It is the most common form of skin cancer, accounting for approximately 80% of all skin cancer cases. BCC is often associated with exposure to ultraviolet (UV) radiation from the sun or tanning beds.
**Why the Correct Answer is Right**
The commonest clinical pattern of BCC is the nodular type, which presents as a single, well-defined nodule or bump on the skin. This type of BCC often has a shiny or pearl-like appearance and is usually painless. The nodular type of BCC is the most common presentation because it is the most aggressive form of BCC, with a high potential for local destruction of surrounding tissue.
**Why Each Wrong Option is Incorrect**
**Option A:** The superficial type of BCC is less common than the nodular type and typically presents as a flat, reddish patch on the skin. It is often more difficult to diagnose than the nodular type.
**Option B:** The morpheaform type of BCC is a rare and aggressive form of BCC that presents as a flat, scar-like lesion on the skin. While it is a significant clinical concern, it is not the most common type of BCC.
**Option C:** The pigmented type of BCC is a rare variant that presents as a pigmented lesion on the skin. While it can be difficult to distinguish from melanoma, it is not the most common type of BCC.
**Clinical Pearl / High-Yield Fact**
The "ABCDE" rule can be used to remember the characteristics of melanoma: Asymmetry, Border irregularity, Color variation, Diameter greater than 6mm, Evolving appearance. However, for basal cell carcinoma, the "ABCD" rule can be used: Asymmetry, Border irregularity, Color variation, Diameter greater than 6mm.
**Correct Answer:** D. Nodular.