CYSTIC HYGROMA

DEFINITION:

A cystic lesion caused by a mass of dilated lymphatics which is usually found in the neck.

EPIDEMIOLOGY:

• incidence: 1/12,000 births
• age of onset:
  • usually at birth or within the first year of life
  • may be identified in utero by ultrasound
• risk factors:
  • M = F

PATHOGENESIS:

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

CLINICAL FEATURES:

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

INVESTIGATIONS:

1. Imaging Studies

1. Ultrasound

• unilocular or multilocular cyst with a thin or thick wall

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

MANAGEMENT:

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

Discussion:

Lymphatic malformations were first described by Redenbacher (1928).Cystic hygroma is one such malformation.

Aetiology: Two theories have been proposed. Mc Clure's & Huntington's theory- lymphatic system develops from mesenchymal clefts in venous plexus reticulum and spreads centripetally towards the jugular sac. Lymphatic malformations arise from sequestration or congenital blockage of the primitive lymphatic anlage.

Sabin's theory - Lymphatic malformations arise from endothelial fibrillar membranes which sprout from the walls of the jugular sac, penetrate surrounding tissue,canalise and produce more cysts.

Pathology: They consist of an aggregation of cysts lined by a single layer of flattened endothelium,filled with lymph,fetal fat and cholesterol crystals.

Classification: Landing & Farber's (1956)

• Lymphangioma simplex-composed of thin walled lymphatic channels.
• Cystic lymphangioma-composed of endothelium lined cysts of varying sizes. e.g : cystic hygroma.
• Cavernous lymphangioma-composed of dilated lymphatics with increased fibrous tissue.

When diagnosed by prenatal ultrasound,they are frequently associated with chromosomal anomalies.

Fetuses with septated cystic hygromas are more commonly associated with turner's syndrome,more likely to develop hydrops and hence have a poorer prognosis whereas fetuses with non septated cystic hygromas are usually associated with Down's syndrome and have a better prognosis.

Other associations include congenital glaucoma,Klippel-Trenaunay syndrome,lymphangiogenic macroglossia and diaphragmatic hernia (Freyn's syndrome).

60 % occur at birth and 90 % by 2 years.

Equal sex incidence except for inguinal hygromas which are five times more common in males.

Usual sites include neck, cheek, axilla, groin, mediastinum and the retroperitoneum. Majority of those in the neck occur in the posterior triangle. Those in the anterior triangle are often associated with intraoral lymphangioma and are the ones likely to produce airway compromise. Mediastinal extension is noted in only 10 % of cases. These swellings are softly cystic, partially compressible (as they are multiloculated) and brilliantly translucent (unless intracystic haemorrhage has occurred).

Diagnosis is usually made clinically and investigations like chest X-ray,CT-scan and MRI are required only to determine the extent of involvement.

The major differential diagnosis is branchial cyst. Treatment is generally recommended because of the risks of

• Spontaneous infection
• Substantial disfigurement due to progressive growth
• Sudden increase in size with spontaneous haemorrhage
• Airway compromise and dysphagia
• Brachial plexus compression with pain and paraesthesia

Treatment Options:

Best treatment is surgical extirpation of all the cysts which may amount to conservative neck dissection.T hose of the neck are best removed through a transverse cervical incision. Those of the axilla are excised through an incision in the axillary crease with retraction of the pectoralis major if necessary. For cervical hygromas extending into the axilla, the cervical portion is dissected till it is seen passing below the clavicle. Then the axillary portion is dissected out through a transverse axillary incision. For Cervicomediastinal ones,transverse cervical incision is usually sufficient. Occasionally an upper sternal split may be necessary to allow excision in continuity. For Parotid hygromas, parotidectomy is not usually necessary as they don't involve the gland.

Slow deliberate dissection with meticulous attention to anatomical detail,excellent haemostasis and wide field exposure is necessary to achieve a good cosmetic result. As they are benign swellings, normal structures in the vicinity like facial, hypoglossal and accessory nerves should not be sacrificed.

Aspiration is done only in the emergency setting when airway compromise results due to rapid increase in size of the swelling.

Incision and drainage is done only if they are infected.

Sclerosant injection is best avoided because of

1. their proximity to major vessels and nerves
2. sclerosants destroy tissue planes and make subsequent surgery difficult.

However, some success has been reported with intralesional injection of bleomycin fat emulsion and OK- 432. OK-432 (PICIBANIL) is a streptococcal lysin which was first used by Ogita and colleagues in Kyoto,Japan (1986).It acts as a biological response modifier and prepares macrophages for release of cytokines like TNF-alpha,IL-1 and CSF. It has the advantage of being used successfully in the intra uterine treatment of cystic hygroma.

Steroid injection and irradiation do not have much of a role. The recurrence rate following surgical extirpation is nearly 10 % and is noted more with those in extra parotid and suprahyoid locations. Most of the recurrences manifest within the first year and are due to residual cysts which grow with the patient. Other complications of surgery include cranial nerve palsies, cosmetic defects, dysphagia and airway compromise.

DISCUSSION:
Lymphatic malformations were first described by Redenbacher (1928).Cystic hygroma is one such malformation.
Aetiology:

Two theories have been proposed.
* Mc Clure’s & Huntington’s theory- lymphatic system develops from mesenchymal clefts in venous plexus reticulum and spreads centripetally towards the jugular sac.Lymphatic malformations arise from sequestration or congenital blockage of the primitive lymphatic anlage.
* Sabin’s theory- Lymphatic malformations arise from endothelial fibrillar membranes which sprout from the walls of the jugular sac,penetrate surrounding tissue,canalise and produce more cysts.
Pathology:

They consist of an aggregation of cysts lined by a single layer of flattened endothelium,filled with lymph,fetal fat and cholesterol crystals.
Classification: Landing & Farber’s (1956)
* Lymphangioma simplex-composed of thin walled lymphatic channels.
* Cystic lymphangioma-composed of endothelium lined cysts of varying sizes. e.g : cystic hygroma.
* Cavernous lymphangioma-composed of dilated lymphatics with increased fibrous tissue.
When diagnosed by prenatal ultrasound,they are frequently associated with chromosomal anomalies. Fetuses with septated cystic hygromas are more commonly associated with turner’s syndrome,more likely to develop hydrops and hence have a poorer prognosis whereas fetuses with non septated cystic hygromas are usually associated with Down’s syndrome and have a better prognosis. Other associations include congenital glaucoma,Klippel-Trenaunay syndrome,lymphangiogenic macroglossia and diaphragmatic hernia (freyn’s syndrome). 60 % occur at birth and 90 % by 2 years. Equal sex incidence except for inguinal hygromas which are five times more common in males.

Usual sites include neck, cheek, axilla, groin, mediastinum and the retroperitoneum.Majority of those in the neck occur in the posterior triangle.Those in the anterior triangle are often associated with intraoral lymphangioma and are the ones likely to produce airway compromise.Mediastinal extension is noted in only 10 % of cases. These swellings are softly cystic, partially compressible (as they are multiloculated) and brilliantly translucent (unless intracystic haemorrhage has occurred).

Diagnosis is usually made clinically and investigations like chest X-ray,CT-scan and MRI are required only to determine the extent of involvement.

The major differential diagnosis is branchial cyst. Treatment is generally recommended because of the risks of
* Spontaneous infection
* Substantial disfigurement due to progressive growth
* Sudden increase in size with spontaneous haemorrhage
* Airway compromise and dysphagia
* Brachial plexus compression with pain and paraesthesia

TREATMENT OPTIONS:

 
* Best treatment is surgical extirpation of all the cysts which may amount to conservative neck dissection.Those of the neck are best removed through a transverse cervical incision.Those of the axilla are excised through an incision in the axillary crease with retraction of the pectoralis major if necessary.For cervical hygromas extending into the axilla, the cervical portion is dissected till it is seen passing below the clavicle.Then the axillary portion is dissected out through a transverse axillary incision.For Cervicomediastinal ones,transverse cervical incision is usually sufficient.Occasionally an upper sternal split may be necessary to allow excision in continuity.For Parotid hygromas,parotidectomy is not usually necessary as they don’t involve the gland.

Slow deliberate dissection with meticulous attention to anatomical detail,excellent haemostasis and wide field exposure is necessary to achieve a good cosmetic result.As they are benign swellings, normal structures in the vicinity like facial, hypoglossal and accessory nerves should not be sacrificed.
* Aspiration – is done only in the emergency setting when airway compromise results due to rapid increase in size of the swelling.
* Incision and drainage is done only if they are infected.
* Sclerosant injection is best avoided because of
1.their proximity to major vessels and nerves
2.sclerosants destroy tissue planes and make subsequent surgery difficult.
However, some success has been reported with intralesional injection of bleomycin fat emulsion and OK- 432. OK-432 (PICIBANIL) – is a streptococcal lysin which was first used by Ogita and colleagues in Kyoto,Japan (1986).It acts as a biological response modifier and prepares macrophages for release of cytokines like TNF-alpha,IL-1 and CSF.It has the advantage of being used successfully in the intra uterine treatment of cystic hygroma.
* Steroid injection and irradiation do not have much of a role. The recurrence rate following surgical extirpation is nearly 10 % and is noted more with those in extra parotid and suprahyoid locations.Most of the recurrences manifest within the first year and are due to residual cysts which grow with the patient. Other complications of surgery include cranial nerve palsies, cosmetic defects, dysphagia and airway compromise.

* Dr.Vijay.R,