**Core Concept**
Cystic hygroma is a congenital malformation of the lymphatic system, characterized by the abnormal development of lymphatic vessels and cystic spaces. This condition is often associated with chromosomal abnormalities and other congenital anomalies.

**Why the Correct Answer is Right**
Cystic hygroma is a known association with various chromosomal syndromes, including Turner's syndrome (45,X), Klinefelter's syndrome (47,XXY), and Down's syndrome (Trisomy 21). The lymphatic malformation in cystic hygroma is thought to be related to the failure of lymphatic vessel development during embryogenesis, which can be influenced by genetic factors. The presence of cystic hygroma in these syndromes is often used as a diagnostic clue, especially in the context of prenatal ultrasound or postnatal examination.

**Why Each Wrong Option is Incorrect**
**Option A:** Turner's syndrome is indeed associated with cystic hygroma, but this does not rule out the other options. The presence of cystic hygroma in Turner's syndrome is a significant diagnostic finding.
**Option B:** Klinefelter's syndrome is also associated with cystic hygroma, but like Turner's syndrome, this does not exclude the other options.
**Option C:** Down's syndrome can be associated with cystic hygroma, but this option is incomplete as it does not account for the other two syndromes.

**Clinical Pearl / High-Yield Fact**
Cystic hygroma is a significant congenital anomaly that can be associated with various chromosomal syndromes, and its presence should prompt a comprehensive evaluation for underlying genetic conditions.

**✓ Correct Answer: D. All of the above**