Cystic hygroma is-
**Core Concept**
Cystic hygroma is a congenital malformation characterized by the abnormal development of the lymphatic system, specifically the lymphatic sacs. This condition leads to the formation of fluid-filled cysts, typically in the neck region. The pathogenesis involves the failure of lymphatic sacs to communicate with the venous system during embryonic development.
**Why the Correct Answer is Right**
The correct answer is a congenital malformation of the lymphatic system. Cystic hygroma arises from the failure of lymphatic sacs to communicate with the venous system during embryonic development. This leads to the accumulation of lymphatic fluid in the resulting cysts. The lymphatic sacs are derived from the jugular lymph sacs, which are responsible for draining lymph from the head and neck region.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the pathogenesis of cystic hygroma. While it is true that cystic hygroma involves the lymphatic system, it is not a neoplastic process.
**Option B:** This option is incorrect because it implies that cystic hygroma is a result of a viral infection, which is not supported by the current understanding of the condition.
**Option C:** This option is incorrect because it does not accurately describe the location of cystic hygroma. While it is true that cystic hygroma can occur in the neck region, it can also occur in other areas such as the axilla and mediastinum.
**Clinical Pearl / High-Yield Fact**
Cystic hygroma is often associated with other congenital anomalies, such as chromosomal abnormalities and cardiac defects. It is essential to investigate for these associated conditions in patients with cystic hygroma.
**Correct Answer: C. Cystic hygroma is a congenital malformation of the lymphatic system.**