Which neck mass is described as spongy, diffuse, and lateral to the sternocleidomastoid muscle?

• A. Thyroglossal duct cyst
• B. Cystic hygroma
• C. Branchial cleft cyst
• D. Enlarged lymph node

Answer: (B)

A cystic hygroma is characterized by a spongy, diffuse texture that feels soft and compressible, and it typically emerges laterally to the sternocleidomastoid muscle. This type of neck mass is often a consequence of lymphatic malformation, which means it has a distinct presentation compared to other types of neck masses. The diffuse quality leads to a more pronounced lateral swelling, and its fluctuant nature is a hallmark feature, making it easily distinguishable during physical examination.

In contrast, a thyroglossal duct cyst typically presents as a firm, midline neck mass that moves with tongue protrusion and is not lateral to the sternocleidomastoid muscle. A branchial cleft cyst generally presents as a well-defined, firm mass along the anterior border of the sternocleidomastoid, rather than a spongy diffuse mass. An enlarged lymph node is usually more discrete and firm compared to the diffuse nature of a cystic hygroma, and it may be accompanied by tenderness or signs of infection, which are not typical features of a cystic hygroma.