1. Background

• cystic hygromas begin to develop at about 40 days gestation and are due to the failure of the embryonic lymphatics to connect with the venous system -> the lymphatics become dilated and continue to grow forming cystic structures
• the left-sided predominance may be due to a failure of the thoracic duct junction to connect with the left subclavian vein
• cystic hygromas are also called cystic lymphangiomas
• location:
  • 75% in the neck
  • 20% in the axilla
  • 5% in the mediastinum, retroperitoneum, or pelvis

1. Cystic Hygromas

• diffuse, non-tender mass usually found in the neck at birth
• soft, well-demarcated, and irregular on palpation
• usually found in the posterior triangle of the neck and most occur on the left side (L>R; 2:1)
• mass may be small -> large
• easy to transilluminate
• small and medium size hygromas are usually asymptomatic
• larger hygromas may extend into the face, mouth, tongue, parotid, larynx, or chest (15% extend into the mediastinum) and can be associated with complications

2. Complications

• upper airway obstruction (stridor, apneas, cyanosis)
• dysphagia
• mandibular maldevelopment
• nerve palsies
• hemorrhage
• infection

1. Imaging Studies

2. Needle Aspiration

• usually a clear or straw-coloured fluid
• may also be bloody, blood tinged, brown, and/or purulent if complicated by hemorrhage or infection

1. Surgery

• surgical removal if large and/or symptomatic
• may require multiple surgeries

2. Prognosis

• depends on size of cyst and if complications
• unpredictable cystic growth and growth into surronding tissues
• some cysts may resolve spontaneously
• recurrence is possible
• normal life span and intelligence