**Core Concept**
Cystic hygromas are congenital malformations of the lymphatic system, characterized by the abnormal formation of lymphatic vessels and cysts. They typically present as soft, fluid-filled masses in the neck, often detected prenatally or at birth.

**Why the Correct Answer is Right**
Cystic hygromas are associated with Turner syndrome, a genetic disorder caused by the absence or abnormality of one X chromosome. This condition leads to various physical and developmental abnormalities, including heart defects, short stature, and infertility. The lymphatic malformations in Turner syndrome are thought to result from the abnormal development of lymphatic vessels during embryogenesis.

**Why Each Wrong Option is Incorrect**
**Option A:** Down syndrome - while Down syndrome is associated with various congenital malformations, it is not typically linked to cystic hygromas.
**Option B:** DiGeorge syndrome - this condition is characterized by thymic hypoplasia and parathyroid gland abnormalities, but it is not directly associated with cystic hygromas.
**Option C:** Ehlers-Danlos syndrome - this is a group of genetic disorders affecting connective tissue, but it is not specifically linked to cystic hygromas.

**Clinical Pearl / High-Yield Fact**
When evaluating a patient with a cystic hygroma, it is essential to consider Turner syndrome and other associated congenital anomalies, as early diagnosis and management can significantly impact the patient's quality of life.

**Correct Answer:** D. Turner syndrome.