Ultrasonography

Ultrasonography is a noninvasive, real-time, high-resolution imaging modality that provides anatomic images supplemented by Doppler evaluation of blood flow. It is equally useful for primary obstetric imaging and for portable bedside evaluation of a neck mass in the restless child.

Prenatal ultrasonography includes routine evaluation of normal anatomic structures of the head, face, and neck, as well as upper airway patency and pattern of swallowing. Airway patency may be difficult to confirm with ultrasonography, hence ancillary signs of airway and upper gastrointestinal tract compromise, such as a small stomach or polyhydramnios, should be routinely searched for. Ultrasonography demonstrates morphologic characteristics of cervical pathology, specifically the cystic or solid nature of any lesion and the presence or absence of fat and calcifications.

Color Doppler provides valuable characterization of a lesion’s vascularity and blood supply, detects possible arteriovenous shunting, and depicts the major neck vessels. Three-dimensional reconstruction clearly depicts the relationship of cervical lesions with adjacent facial and skull base structures (e-Fig. 14-1). Potential shortcomings of ultrasonography involve cases with poor acoustic windows because of an anterior position of the placenta, maternal obesity or polyhydramnios, and abnormal fetal position with unusual flexion and extension of the fetal neck.

Ultrasonography imaging of congenital neck lesions in young children is performed with high-resolution (3 or 5, up to 12 megahertz [MHz]) transducers. The examination is fast and usually requires no sedation. Reliable distinction of the cystic or solid nature of the lesion may be sufficient for diagnosis in some instances; however, assessment of surrounding tissue invasion may be suboptimal.

Computed Tomography

CT with contrast administration is a valuable tool in the evaluation of neonatal neck masses and, in many instances, may serve as a first imaging test. Modern multidetector CT scanners allow for fast image acquisition in the axial plane and reformatted images in orthogonal planes, thereby avoiding additional radiation to the child. Additionally, the short duration of scanning may help avoid the need for sedation. CT imaging of cervical lesions is especially helpful in the depiction of calcifications, blood products, and bony involvement. However, soft tissue resolution may be suboptimal for accurate lesion characterization, and further imaging with MRI may be necessary.

Magnetic Resonance Imaging

MRI is a superb imaging modality for the evaluation of fetal or neonatal neck lesions and may help further clarify the lesion’s relationship with surrounding structures. Fetal MRI is considered safe to perform in the second and third trimesters for further assessment of a cervical mass detected by routine obstetric ultrasonography. Fetal MRI is approved by the U.S. Food and Drug Agency for magnet field strengths up to 3.0 Tesla.

Fetal imaging prior to 18 weeks of gestational age is typically of little value because of the unknown safety profile of exposure to magnetic fields during organogenesis, as well as the relatively poor image quality in a small fetus. For fast and effective performance of fetal MRI, familiarity and optimal use of imaging sequences is crucial.

Useful MRI sequences for fetal neck imaging include the following:

MRI sequences for imaging of neonatal neck lesions include the following:

Prenatal neck imaging sometimes may be more useful in the evaluation of lesion extension and, particularly, airway and upper gastrointestinal tract patency, rather than the establishment of a precise diagnosis. Knowledge of airway status may help facilitate prenatal counseling and management, including the decision to utilize the ex utero intrapartum treatment procedure. This procedure may be required for fetuses diagnosed with a giant neck mass to gain time to secure an airway while the neonate is still attached to the umbilical cord.

The postnatal appearance of prenatally diagnosed cervical lesions may be of additional diagnostic value, as certain lesions may have a predictable developmental pattern. For example, congenital hemangiomas may remain stable in size or become smaller, whereas teratomas are likely to increase in size; lymphatic malformations may develop blood-fluid levels caused by intralesional hemorrhage. For this reason, it is important to evaluate a cervical lesion throughout its phases of development.

Hemangioma

Hemangioma is the most common vascular tumor of infancy. Two major types are recognized: (1) congenital (rare) and (2) infantile (common). The previously used categorization of hemangioma types as capillary, juvenile, or cavernous is no longer accepted. It should be noted that all types of hemangiomas have overlapping clinical, imaging, and histopathologic features.

Infantile Hemangioma

Infantile hemangiomas are benign vascular neoplasms, with an increased incidence in premature children with low birth weight. These lesions have a predictable clinical course notable for early proliferation, which is often followed by spontaneous involution. Growth and involution continue with the following stages. The nascent phase may be observed in the first 2 to 4 weeks of life. A precursor lesion such as macula, multiple telangiectasias, or discoloration in a beard distribution may be seen at birth. The proliferative phase is remarkable for rapid growth of the tumor in the first year of life. At the proliferative stage, the hemangioma appears as a bulky compressible lesion of strawberry-red color and may have cutaneous as well as deep components.

On cross-sectional imaging, it appears as a lobulated mass with intense uniform enhancement, which usually demonstrates intralesional flow voids on MRI (Fig. 14-2, A). Proliferation may be biphasic. Careful assessment of upper airway status is important because the deep portions of a cervical hemangioma may enlarge sufficiently at this stage to impinge on the airway and cause obstruction. During the final involution phase, which may continue for up to 12 years, the rate of regression is variable. Involution is never complete, although the residual lesion may not be grossly visible; in the neck, it leaves persistent fibrofatty tissue. Infantile hemangiomas are positive for the glucose transporter 1 (GLUT-1) marker at all stages of lesion development.

Most infantile hemangiomas do not cause any morbidity or mortality but may create cosmetic inconvenience. Nonetheless, a hemangioma of the neck is considered an alarming lesion if it assumes a beard distribution (involvement of the lower face, anterior neck, and submandibular and parotid regions) because of an increased incidence of subglottic hemangioma, high risk of airway compromise, and known association with PHACES syndrome (Posterior fossa malformations, Hemangiomas, Arterial, Cardiac anomalies, Eye anomalies, Sternal cleft). The arteriopathy of PHACES syndrome commonly comprises a spectrum of congenital and progressive large arterial lesions ipsilateral to the cutaneous hemangioma. It entails careful searching (and monitoring) with imaging for potential vascular anomalies once a diagnosis of cervicofacial segmental hemangioma is established.

Upper airway hemangiomas (see Fig. 14-2, B and C) become symptomatic in the proliferative phase, causing biphasic stridor, respiratory distress, and potentially even life-threatening airway obstruction, which may require emergent intubation. These hemangiomas are often multifocal and occur above and below the vocal cords. Close monitoring with cross-sectional imaging may be indicated because laryngoscopy may not accurately depict the degree of invasion. MRI is preferred in the setting of intubation or tracheostomy.

In rare cases, cervicofacial infantile hemangioma may be associated with central nervous system hemangiomas in intracranial (see Fig. 14-2, D) or intraspinal locations. The reported cases of central nervous system hemangiomas indicate a specific pattern of distribution, with a predilection for the basal cisterns, ventricular system, and extradural spinal involvement.

In the past, infantile hemangiomas have been confused with other vascular neoplasms, particularly kaposiform hemangioendotheliomas (KHEs) and tufted angiomas, especially in the setting of consumptive coagulopathy, referred to as the Kasabach-Merrit phenomenon; it is now generally accepted that infantile hemangiomas are rarely, if ever, responsible for this phenomenon.

Congenital Hemangioma