**Core Concept**
Klippel-Trenaunay syndrome (KTS) is a rare congenital disorder characterized by the triad of port-wine stains, varicose veins, and limb hypertrophy. This condition is a result of an abnormal development of blood vessels, leading to an increased blood flow to the affected limb.

**Why the Correct Answer is Right**
KTS is a vascular malformation that involves the proliferation of blood vessels, including veins, arteries, and capillaries. The port-wine stains are due to the presence of abnormal capillaries in the skin, while the varicose veins are a result of the increased blood flow and venous pressure. Limb hypertrophy occurs due to the increased blood flow and subsequent growth of the affected limb. The deep veins are often anomalous, which can lead to complications such as deep vein thrombosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Not all patients with KTS have port-wine stains; however, these are a common feature of the condition.
**Option B:** While cutaneous blemishes may be present, they are not a specific feature of KTS.
**Option C:** Limb atrophy is more commonly associated with certain types of vascular malformations, such as Klippel-Trenaunay-Weber syndrome.
**Option D:** This statement is not specific to KTS and can be hazardous in any surgical procedure involving the saphenous vein.

**Clinical Pearl / High-Yield Fact**
Klippel-Trenaunay syndrome is a rare congenital disorder that requires careful management to prevent complications such as deep vein thrombosis and pulmonary embolism. A thorough understanding of the condition and its features is essential for accurate diagnosis and treatment.

**Correct Answer:** C. Limb hypertrophy.