Case 31

Discussion:

Fetal cystic hygromas are congenital malformations of the lymphatic system appearing as single or multiloculated fluid-filled cavities. Approximately 75–80 percent of all cystic hygromas involve the neck and the lower portion of the face. They tend to be infiltrative without respect to fascial planes. They often progress to hydrops and cause fetal death. The majority (about 80–90 percent) are detected by the time the patient is 2 years old. Approximately half of these fetuses have monosomy X (Turner syndrome), while 10-15 percent of cases have trisomy 18, 21 or 13. Cystic hygromas are midline, posterior, septated, cystic masses without associated bone defects. They frequently contain a characteristic appearing midline nuchal ligament.

The differential considerations include: encephalocele, meningomyelocele, and teratoma. Teratomas are typically solid in nature. Encephaloceles have associated calvarial abnormalities and may contain brain tissue. Meningomyeloceles are most of the time encountered in the lumbar region.

References:

• Rangel, V., Having, K. (2008). Cystic Hygroma. Journal of Diagnostic Medical Sonography 24: 218-222
• Koeller, K. K., Alamo, L., Adair, C. F., Smirniotopoulos, J. G. (1999). From the Archives of the AFIP: Congenital Cystic Masses of the Neck: Radiologic-Pathologic Correlation. RadioGraphics 19: 121-146