Synonyms: Lymphatic hamartomas, (cystic) lymphangioma, hygroma colli cysticum and jugular lymphatic obstructive sequence.

Definition: Uni- or multilocular lymphatic hamartomas ranging in size from several millimeters to 80 mm, containing a clear or cloudy fluid like lymph.

Prevalence: It is not well defined. Reports range from 1.6:10,000 pregnancies to 0.8% of pregnancies at risk for having a structural anomaly.

Etiology: Variable, probably multigenic.

Pathogenesis: Jugular lymphatic obstruction sequence, abnormal embryonic sequestration of lymphatic tissue, or abnormal budding of the lymphatics.

Associated anomalies: see table 1.

Differential diagnosis: see table 2.

Prognosis: The prognosis for the axillary form is variable.

Recurrence risk:  Not increased.

Management: Standard obstetrical care.

MESH Lymphangioma-diagnosis; Thoracic-Neoplasm,-congenital BDE 3284 MIM 257350 ICD9 2281 CDC 228.100 (non-neck location), 239.200 (neck location)

Address correspondence to Vincenzo Suma, MD, Ultrasonic Service, Division of Obstetrics and Gynecology, Civilian Hospital, 35100 Padua, Italy. Ph 39-49-821-13481; Fax: 39-49-821-3493.

Introduction

The prenatal diagnosis of cystic hygroma by ultrasound is well documented in the literature^1-3. This malformation is commonly localized in the nuchal region (75% of cases). An additional 20% are found in the axilla, while the remaining 5% are found in the mediastinum, retroperitoneum, abdominal viscera, groin, bones and scrotum⁴ (fig. 9).

A previous report has demonstrated the prenatal appearance of axillary cystic hygromas⁵. In this paper we discuss a case of a complex echo mass in the left mid-axillary line of the fetus diagnosed in utero as cystic hygroma and confirmed at birth. A postnatal CT scan revealed the intrathoracic extension of the mass.

Case report

A 31-year-old G₂P₁₀₀₁, was examined by ultrasound at 26 weeks of gestation to verify the age of the fetus. There was no family history of congenital anomalies. The patient"s antepartum course had been unremarkable. Ultrasound evaluation revealed an active single fetus (cephalic presentation, posterior placenta, normal amniotic fluid and three-vessel umbilical cord). Head circumference, biparietal diameter, bilateral femur lengths and abdominal circumference measurements were compatible with 28 weeks of gestation.

Morphological evaluation of the fetus revealed a multiseptated cystic mass of 85 by 70 mm (fig. 1-3) that, apparently, involved the right lateral chest wall and the axillary region.

Fig. 1: View of the chest and right arm at 26 weeks. A multicystic mass (M) surrounds the humerus (H) and extends to the chest wall. (S = spine, h = heart).

Fig. 2: Humerus (H) and the cystic mass (M) at its proximal end.

Fig. 3: View of the axillary region showing the mass.

This mass contained of a single dominant thin walled, multiseptated loculation.

There was no polyhydramnios or other evidence of fetal hydrops. No additional fetal defects were visualized. Repeated sonographic scans at 28, 33 and 36 gestational weeks did not demonstrated any enlargement of the cystic mass.

The diagnosis of axillary cystic hygroma was made. A normal 46,XX karyotype was demonstrated by cordocentesis. Amniotic fluid alpha-fetoprotein and maternal serum alpha-fetoprotein were normal.

Postnatal course

The patient delivered a female newborn at 40 weeks. She had an Apgar index of 8 at 1 min and 10 at 5 min. The weight was 3,450g. Physical examination revealed a nodular mass in the right midaxillary line, not adherent to underlying bone (fig. 4) and extending as far as the 10^th rib.

Fig. 4: Cystic hygroma of the axillary region at birth.

Fig. 5: Angioma of the right hand.

On the right hand there was a plain angioma (fig. 5). The baby was transferred to the Neonatal Intensive Care Unit. A chest  X-ray revealed no other pathology. Sonography of the axillary mass did not show involvement of the thoracic muscles. An abdominal sonography revealed that the liver, pancreas, kidneys and spleen were normal. Doppler sonography of the vessels of the right arm was normal, and no arteriovenous fistulas were seen.

Forty-eight hours after delivery a cystic mass appeared in the right side of the neck, similar to the other mass in axilla (fig. 6).

Fig. 6: Swelling of the lymphangioma of the neck, 48 hours after birth. Compare to fig. 5.

The baby underwent surgery and the cystic hygroma was partially removed. It extended from the jugular region to the thoracic wall, involving the skin and muscles. It was not possible to perform a complete excision of the mass, because of its extension. The pathological examination of the mass confirmed the diagnosis of lymphangioma.

Forty-seven days after surgery, a CT scan revealed a mass invading the cervical region from the mandibular angle to the supraclavicular region, the right thoracic wall, and the mediastinum. The size of the mass was 40 mm in the cervical area, 50 mm in the supraclavicular region, 70 mm in the chest and 60 mm in the mediastinum. In the cervical area and at the thoracic inlet, the trachea, the esophagus and the mediastinal fat were displaced (fig. 7-8).

Fig. 7: CT scan showing the involvement of the chest wall by the multilocular mass.

Fig. 8: CT scan of the thoracic inlet. Note the displacement of the trachea and esophagus to the left.

At present the baby is well and should undergo another operation within the next few months.

Discussion

Pathogenesis

There are at least three theories to explain the origin of cystic hygroma. The first theory⁶ suggests that an early jugular-lymphatic obstructive sequence could cause hydrops fetalis, pterigium colli and cystic hygroma. This obstruction impedes communication between the jugular lymphatic sacs and the internal jugular vein.

Other authors^7-8 believe cystic hygroma is caused by an abnormal embryonic sequestration of lymphatic tissue and its subsequent failure to join normal lymphatic channels.

A third theory⁹ suggests that abnormal budding of the lymphatics occurs between the sixth and ninth weeks of gestation. These then canalize to form lymph-filled cysts.

Of these three theories, the first seems the most likely. However, the other two theories could be applied to noncervical lymph­angyomatosis.

Location

In most cases, cystic hygromas are localized in the neck (fig. 9).

Fig. 9: Distribution of cystic hygromas. The most common region is the neck (75%) followed by the axillary region (20%). Other distributions are much less common.

The biggest masses can be so large as to reach the floor of the mouth and the tongue. They can also reach the cheek, parotid, axilla and mediastinum. In their descent toward the mediastinum, they follow the phrenic nerve between the subclavian vessels¹⁰. Cystic hygromas confined to the mediastinum are rare; they usually represent mediastinal invasion by cervical hygroma and are found in about 2-3% of cases¹¹.

Types

Lymphangiomas are made up of lymphatic vessels and are, fundamentally, endothelial cells limiting spaces and supporting connective tissue. There are three groups:

·        simple lymphangioma, formed by lymphatic capillaries;

·        cavernous lymphangioma, formed by bigger lymphatic vessels with a fibrous adventitia;

·        cystic lymphangioma, commonly called hygroma, formed by multiple cysts ranging from a few millimeters to several centimeters in size.

These cysts are filled with a lymph-like clear or muddy fluid. No communication exists between the lymphatic system and a cystic hygroma. Cystic hygromas have a predilection for local infiltration of the dermis, subcutaneous tissue, and soft tissue, and occasionally they are widespread. The neck, axilla and chest may be particularly prone to this infiltrative behavior due to the local prevalence of major muscular and neurovascular bundles loosely embedded in fat⁵.

About 50% of these are present at birth, and up to 90% become evident by two years of age. The incidence of cystic hygroma is approximately 1.6:10,000 pregnancies or 0.8% of pregnancies at risk for a structural anomaly^1,12,13.

Associated anomalies

Although the cystic hygroma may be isolated, in many cases it is associated with hydrops fetalis. Chromosomal defects, particularly monosomy X (Turner"s syndrome) and a wide variety of anatomic abnormalities (Table 1) are found in more than 80% of the fetuses^2,13,14.

In our patient, who has a normal female karyotype and no morphological anomalies, ultrasound probing of the axillary cystic hygroma showed the top of a larger lymphangyomatosis that extended to the neck, chest and mediastinum.

Ultrasound diagnosis

The characteristic sonographic appearance shows asymmetric, multiseptate, thin-walled cystic masses localized in the axilla¹⁵. Occasionally the cystic mass may have a more complex echotexture with cystic and solid components. This occurs when the obstructed lymphatic channels are among muscle and fibrous tissue or when portions of the abnormal lymphatic tissue remain clumped together¹⁶.

In our opinion, it is a good idea to use the clavicular extremity of the humerus as a  reference point in the diagnostic approach and management of axillary cystic hygroma. Scanning along the humerus longitudinal axes makes it possible to identify, using the clavicular extremity of the humerus as a reference, a cystic multiseptated, thin-walled mass, extending towards the amniotic fluid (fig. 3).

Differential diagnosis

The differential diagnosis should consider the possible masses involving the chest  and abdominal walls (Table 2).

Cervical teratoma, a complex structure made up of liquid and solid parts, generally involves the anterolateral portion of the neck, causing hyperextension. It does not involve the axilla or thoracic wall¹⁷.

Cystic hygroma of the axillary space should be differentiated from the limb-body wall complex. This anomaly involves both the thorax and abdomen and is characterized by a complex, bizarre appearing mass entangled with membranes and containing eviscerated organ. Limb defects, scoliosis, neural tube and craniofacial defects are associated^18,19.

Defects such as omphalocele and gastroschisis are easily recognized by their location and because of the eviscerated organs^20,21.

Ectopia cordis²² is classified according to its location: cervical, thoraco-cervical, thoraco-abdominal and abdominal. In the majority of cases (55%), it is thoracic or thoraco-abdominal and belongs to a complex malformation syndrome known as the pentalogy of Contrell²³. Extrathoracic demonstration of the heart makes the differential diagnosis easier, while some difficulties may arise when there is only a partial herniation²⁴.

In cases of large cystic hygroma²⁵, the identification of the midline septation extending from the neck and representing the posterior nuchal ligament, constitutes the most specific sign for the differential diagnosis of hygromas located in other sites.

Cystic hygroma of the axillary space must be differentiated from high thoracic myelomeningocele²⁶. The latter usually has a cystic structure containing only cerebrospinal fluid and neural elements (myelomeningocele). Cranial signs (ventricular dilatation, “lemon” sign, and “banana” sign²⁷) are also usually present.

Prognosis

The prognosis depends on the presence or absence of associated hydrops, chromosomal aberrations and anatomic defects.

Spontaneous resolution of a cystic hygroma of the neck in a fetus affected by Turner"s syndrome²⁸ and a fetus with normal karyotype have been described²⁹.

The presence of hydrops fetalis or lymphangiectasia indicates a serious prognosis, with a mortality rate of 100 percent within a few weeks from diagnosis¹⁵.

Two recent reports^5,30 suggest that isolated cystic hygroma in a typical location in the neck or axilla may have a better prognosis.

In the literature, 32 cases of cystic hygroma in children are reported. In 12 cases the hygroma was localized in the neck, while in the remaining cases it was in rare sites⁴. Of these, six had hygromas in the axilla and chest wall, five in the mesentery and nine had lymphangiomas localized in various uncommon sites such as cervico-mediastinum, retroperitoneum, scrotum and multiple sites.

The complete excision of the cystic mass was possible in 23 cases⁴. In another seven cases, only partial removal was possible because of the size of the cystic mass. Two of the twenty-three patients who underwent complete excision died during the postoperative period. It appears that the prognosis for these babies depends largely on the anatomical location and size of the tumors and on the ability of the pediatric surgeon to remove the masses.

Obstetrical management

When a prenatal diagnosis of cystic hygroma is made, the determination of the karyotype is recommended in all cases. Serial sonograms to assess the growth of the mass and monitoring for the development of hydrops should aid in the management of the pregnancy and are useful in the counseling of future pregnancies.

In the fetus with associated hydrops, the chance of survival is small; therefore, a non-aggressive approach is advisable. The option of pregnancy termination should be offered before viability.

If there is a small isolated cystic hygroma, no modification of standard obstetrical management is required (p 2281-7). When large lesions are present, a cesarean section may be advisable.

References

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