**Core Concept**
Keloid scars are a type of raised, thickened skin lesion that occurs after skin injury, characterized by an overgrowth of collagen and other connective tissue components. They are distinct from hypertrophic scars, which are also raised but do not extend beyond the original wound boundaries.

**Why the Correct Answer is Right**
Keloid scars are composed of an abnormal accumulation of collagen type I and III, along with other extracellular matrix components such as glycosaminoglycans and fibronectin. This excessive collagen deposition is mediated by the action of fibroblasts, which produce growth factors and cytokines that stimulate collagen synthesis and deposition. The resulting keloid scar is a dense, fibrotic tissue that can be itchy, painful, and cosmetically concerning.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because keloid scars are not primarily composed of inflammatory cells, although there may be some inflammation present.

**Option B:** This option is incorrect because keloid scars do not typically contain a significant amount of melanocytes, which are the cells responsible for producing pigment in the skin.

**Option C:** This option is incorrect because keloid scars are not primarily made up of fat tissue, which is more characteristic of lipomas or other types of benign fatty lesions.

**Clinical Pearl / High-Yield Fact**
Keloid scars are more common in individuals with darker skin types and can be triggered by various factors, including genetic predisposition, trauma, and certain medical conditions such as autoimmune disorders. Treatment options for keloid scars may include topical corticosteroids, silicone gel sheeting, and surgical excision, although recurrence rates can be high.

**Correct Answer: A. Keloid scars are primarily composed of an abnormal accumulation of collagen type I and III, along with other extracellular matrix components.**