Scleroderma involves:
**Core Concept**
Scleroderma is a chronic autoimmune disease characterized by fibrosis and thickening of the skin and internal organs, leading to loss of function and potentially life-threatening complications. The pathogenesis involves a complex interplay of immune system dysregulation, vascular damage, and excessive production of collagen.
**Why the Correct Answer is Right**
Scleroderma is primarily driven by an abnormal immune response, where autoantibodies target and damage the body's own tissues. The disease is characterized by the presence of autoantibodies against topoisomerase I (anti-Scl-70) and centromere protein B (anti-CENP-B). The immune complex deposition and activation of complement lead to inflammation, endothelial damage, and the release of pro-fibrotic cytokines, such as transforming growth factor-beta (TGF-β). This promotes the proliferation and activation of fibroblasts, resulting in the excessive production of collagen and fibrosis.
**Why Each Wrong Option is Incorrect**
**Option A:** Scleroderma is not primarily a disorder of collagen synthesis, but rather a complex autoimmune disease with fibrosis as a secondary consequence.
**Option B:** While scleroderma does involve vascular damage, it is not primarily a vasculitis, but rather a disease of immune dysregulation and fibrosis.
**Option C:** Scleroderma is not a disorder of calcium metabolism, but rather a complex autoimmune disease with fibrosis and vascular damage.
**Clinical Pearl / High-Yield Fact**
Scleroderma is often classified into two main types: limited systemic scleroderma (LSS) and diffuse systemic scleroderma (DSS). LSS is characterized by skin involvement limited to the face, hands, and feet, while DSS involves widespread skin thickening and internal organ involvement.
**Correct Answer: D. Systemic sclerosis. Scleroderma.**