5 Neck


5 Neck

Erik Beek

The structures of the neck are superficially located and easily examined with ultrasound. The retropharyngeal region is an exception because of the interposed air-filled pharynx. The deep lobe of the parotid gland is hidden behind the bony ramus of the mandible.

A high-frequency linear array transducer (15.5 MHz) can exquisitely show the structures of the neck. However, a successful examination depends for a great part on the cooperation of the patient. Patience is required. The use of warm coupling gel can be advantageous. A small pillow under the shoulders improves access to the neck but can be perceived as threatening. Its use can be postponed until a later stage of the examination.

The most common reason why an ultrasound examination is requested in our hospital is to assess the patency of the jugular and subclavian veins before the insertion of a central line. The technique is described below. The second most common reason is to evaluate a swelling. Ultrasound can in the vast majority of patients differentiate cystic from solid lesions. If considered in combination with the location of a swelling, the patient’s age, signs, and symptoms, and the laboratory data, ultrasound can often provide a straightforward diagnosis, such as a second branchial cleft cyst or fibromatosis colli.

Another common question is whether inflammation of neck structures has progressed to abscess formation.

The following paragraphs will describe the most common anomalies of the neck that are examined with ultrasound.

5.1 Normal Anatomy and Variants

The structures of the neck are easily imaged. A complete study should include the following:

The echogenic parotid gland over the ramus of the mandible ( Fig. 5.1 , Fig. 5.2 , Fig. 5.3 );

Fig. 5.1 Normal parotid gland (arrow) in a 2-month-old boy.
Fig. 5.2 Normal parotid gland in an 8-year-old boy.
Fig. 5.3 Normal parotid gland in a 6-year-old girl. Often, small islands of lymphoid tissue (arrows) are seen.

The more hypoechoic and coarse submandibular gland at the tip of the parotid gland, medial to the mandibular angle ( Fig. 5.4 and Fig. 5.5 );

Fig. 5.4 Normal submandibular gland (arrow) in a 2-month-old boy.
Fig. 5.5 a, b Normal submandibular gland in a 5-year-old girl (arrow, a) and in a 13-year-old girl (arrows, b).

The sublingual gland in the floor of the mouth ( Fig. 5.6 and Fig. 5.7 );

Fig. 5.6 Normal sublingual glands (arrows) in an 8-year-old boy.
Fig. 5.7 Normal sublingual glands (arrows) in a 13-year-old girl. Note the mylohyoid muscle (arrowheads).

The homogeneous echogenic thyroid gland in the midline in the lower neck ( Fig. 5.8 , Fig. 5.9 );

Fig. 5.8 Normal thyroid gland (arrows) in a 2-month-old boy.
Fig. 5.9 a, b Normal thyroid gland (arrows) in a 13-year-old girl. Transverse (a) and sagittal (b) views.
Fig. 5.10 Normal thymus (arrow) in a term neonate.

The more hypoechoic thymus in the suprasternal notch ( Fig. 5.10 , Fig. 5.11 );

Fig. 5.11 Normal thymus in a 2-month-old boy (arrowheads).

The carotid and subclavian arteries and the jugular and subclavian veins ( Fig. 5.12 , Fig. 5.13 , Fig. 5.14 , Fig. 5.15 , Fig. 5.16 ).

Fig. 5.12 Transverse view of the right subclavian artery (arrow) and vein (arrowhead).
Fig. 5.13 Transverse view of the left jugular vein (arrow) and common carotid artery (arrowhead) in a 2-month-old boy.
Fig. 5.14 Six-year-old girl. Transverse view of the subclavian artery (arrow) and vein (arrowhead).
Fig. 5.15 Six-year-old girl. Longitudinal view of the subclavian artery (arrow).
Fig. 5.16 Six-year-old girl. Longitudinal view of the subclavian vein (arrow). The vein will show changes in diameter with respiration, unlike the subclavian artery.

In healthy children, lymph nodes are almost invariably present. A large node is located laterally under the floor of the mouth, just behind the meeting point of the parotid and submandibular glands. See the section on lymphadenopathy.

Tips from the Pro

  • Use the highest-frequency linear array transducer that still shows enough of the deeper structures.

5.2 Pathology

5.2.1 Vessels of the Neck

One of the most common reasons why ultrasound of the neck is requested is to demonstrate patency of the jugular, subclavian, and brachiocephalic veins before the insertion of a central venous line. The examination is generally easy to perform, although restlessness of the child can pose a problem, especially if combined with crying, which hampers Doppler measurements.

The internal jugular vein is easily seen lateral to the common carotid artery. The right jugular vein is usually larger than the left jugular vein. The distal subclavian vein can be picked up in the sagittal plane below the collar bone, superficial and caudal to the subclavian artery. After redirection of the transducer along the length of the vein, Doppler measurements can be done. More medially, the subclavian vein can be seen from a window above the collar bone, and its confluence with the jugular vein. The left brachiocephalic vein is seen when the neck of the child is extended or a pillow is placed under the shoulder blades. The superior caval vein can be seen in infants through the thymus, but in older children, it is often hidden behind the lung.

Normal veins vary in caliber with the respiratory cycle. Thrombosed veins do not collapse and cannot be compressed. A thrombus is echogenic ( Fig. 5.17 ), although fresh thrombus can be almost anechoic ( Fig. 5.18 , Fig. 5.19 , Fig. 5.20 ). In thrombosis, collaterals can be present, but a collateral vein can be mistaken for the normal vein. Look for the presence of superficial veins in a patient as a sign of collateral circulation. A thrombosis can be clinically occult.

Fig. 5.17 Seventeen-year-old boy with recurrence of leukemia. This color Doppler image shows a calcified thrombus (arrow) at the transition from the right subclavian vein to the brachiocephalic vein.
Fig. 5.18 a, b a Thrombosed right subclavian vein (arrow) in a 12-year-old boy with a peripherally inserted central catheter (PICC line). The axillary and basilic veins were also thrombosed. Some echogenic material is visible in the vein. b Flow is absent on color Doppler.
Fig. 5.19 Seven-year-old girl with a Hickmann catheter in the right subclavian vein. A large thrombus in the superior caval vein (arrow) is seen. Blood flows around the thrombus on color Doppler.
Fig. 5.20 a–c Twelve-year-old girl with a peripherally inserted central catheter (PICC line) via the left arm. a A large thrombus (arrow) is seen in the left subclavian vein, extending into the left brachiocephalic vein. b The left jugular vein is open, but no flow is detected on Doppler examination. c Flow is detected in the right jugular vein.

Sometimes, a large swelling can be seen laterally in the lower neck when a child is crying or pushing. Ultrasound can demonstrate an enlarged, ectatic external jugular vein.

Tips from the Pro

  • If you are requested to look for a thrombus at the tip of a central venous line, study a plain chest film to locate the tip before you start your sonographic examination.

  • Know the location of normal veins, and do not mistake a collateral vein for a patent normal vein.

5.2.2 Cystic Lesions

Thyroglossal Duct Cyst

A thyroglossal duct cyst is a remnant of the thyroid gland that is detached during the descent of the gland from the base of the tongue to the lower neck. The cyst is located within 2 cm of the midline. Most are exactly in the midline between the thyroid gland and the hyoid bone, but they can occur above the level of the hyoid bone. The contents can be clear or cloudy, especially after being infected ( Fig. 5.21 , Fig. 5.22 , Fig. 5.23 , Fig. 5.24 ). The cyst should move upward during swallowing. The differential diagnosis of a thyroglossal duct cyst is epidermoid or dermoid cyst.

Fig. 5.21 a, b Two-year-old girl with a midline swelling. a An intermediate echogenic structure slightly right of the midline at the level of the hyoid bone is seen on a transverse image (arrow). b A normal thyroid gland is present (arrowheads). Pathology was concordant with a thyroglossal duct cyst.
Fig. 5.22 Three-year-old girl with a small midline tumor. Between the hyoid bone and the thyroid gland, a small hypoechoic cyst is demonstrated (arrow). It was resected with a central part of the hyoid bone (Sistrunk procedure). Pathologic examination showed a thyroglossal duct cyst.
Fig. 5.23 Three-year-old girl with a swelling in the anterior neck for a few weeks. A hypoechoic, smooth tumor is seen. This could be a thyroglossal duct cyst or a dermoid cyst. Pathologic examination showed a dermoid cyst.
Fig. 5.24 a, b Thirteen-year-old girl with a fluctuating mass in the neck for 3 years. Ultrasound showed (a) a small cyst (arrow) to the right of the midline at the level of the hyoid bone and (b) a larger cyst (arrow) slightly lower on the left. No communication was seen. Also on magnetic resonance imaging, no connection between the cysts was observed. Pathology was concordant with a thyroglossal duct cyst.

In postoperative patients, imaging is more difficult. Sometimes, a cystic lesion is visible, but on other occasions an unclear clump of tissue with variable echogenicity is seen ( Fig. 5.25 ).

Fig. 5.25 Five-year-old boy, operated on three times for a thyroglossal duct cyst. A swelling and redness appeared in the middle of the scar. Ultrasound shows an irregular hypoechoic structure extending into the deeper tissue. The lesion moved with swallowing. The ultrasound findings are consistent with inflammation and possibly a small abscess. The boy underwent surgery again. On pathology, scar tissue was found and a small remnant of a cyst wall.

Always image the thyroid gland itself because anecdotal stories tell of patients whose only ectopic thyroid tissue was located in the cyst itself. If a normal thyroid gland is demonstrated with ultrasound, then confirmation with radionuclear imaging is not necessary.

Cysts are treated surgically with a Sistrunk procedure, which entails excision of the cyst and its track along with the central part of the hyoid bone.

Branchial Cleft Cyst

Branchial cleft cysts develop from remnants of the branchial apparatus. Most common are cysts of the second branchial arch and pouch. These lesions usually present in teenagers as a slowly growing mass in the lateral neck or, when infected, as a painful swelling where no tumor was noted before. The location of the cyst is anteromedial to the sternocleidomastoid muscle and anterolateral to the carotid artery and jugular vein ( Fig. 5.26 ). Although a cyst, it usually contains debris ( Fig. 5.27 ). It is sharply demarcated with a thin wall. Ultrasound can be helpful during treatment with sclerosing agents. If the cyst is infected, the wall thickens, with increased flow seen on color Doppler. Debris will be present.

Fig. 5.26 a, b Six-year-old girl with a swelling in the lateral neck for 9 months. a A branchial cleft cyst is seen anteromedial to the sternocleidomastoid muscle (M SCM) and anterolateral to the common carotid artery (ACC). VJ, jugular vein. b The cyst is in close contact with the submandibular gland.
Fig. 5.27 a–c a Typical image of a branchial cleft cyst in a 9-month-old boy. The cyst is filled with debris, which swirls when the child is moving. b A branchial cleft cyst in a 12-year-old boy. c A more atypical cyst in a 12-year-old girl. She had a fluctuating mass in the right neck for 3 months. On ultrasound, a rather solid-looking mass is seen without vascularity. Differential diagnosis: lymph node abscess or inflamed branchial cleft cyst. At operation, pus was seen. On pathology, a branchial cleft cyst was identified.

Cysts from the first, third, and fourth arches are less frequent. Sinus and fistulas can be present ( Fig. 5.28 , Fig. 5.29 , Fig. 5.30 ). Ultrasound can demonstrate accompanying cysts, but in producing fistulas, a contrast fistulogram is indicated to demonstrate the tract and a possible connection to the pharynx. This diagnosis is very difficult with ultrasound.

Fig. 5.28 Four-month-old boy with a small pit in the right neck. Underneath it, a cystic structure (arrow) is visible that could not be traced into the deeper structures.
Fig. 5.29 Four-year-old boy with a sinus (arrow) in the right lateral neck. Beneath it, a cystic structure is visible, compatible with a branchial cleft cyst, which extends cranially.
Fig. 5.30 a–c Five-year-old boy with a fistula in the right neck. a Ultrasound shows a tract (arrow) coursing deep to the sternocleidomastoid muscle. On magnetic resonance imaging, no abnormalities were seen. A fistulogram (b, c) demonstrates a connection (arrows) to the right tonsillar fossa.

Dermoid Cyst

A dermoid cyst is a cystic teratoma that contains developmentally mature skin and adnexa of the skin, such as sweat glands, hair follicles, hair, and sebaceous glands. Dermoid cysts are benign. An epidermoid cyst is lined by epithelium and contains keratin. Calcifications are absent.

In the head and neck region, two types of dermoid cyst occur: orbital cysts and cysts in the subcutaneous tissue, often in the floor of the mouth or suprasternal notch. The most common site for an orbital dermoid cyst is at the lateral eyebrow, where it develops around the zygomaticofrontal suture. The cyst can also present at the medial orbit or on the skull.

On ultrasound, the lesion is sharply demarcated, oval, and hypoechoic (see Fig. 5.30 ). Where the tumor abuts the skull, a depression of the bone is often visible. A very hyperechoic inner border of the cyst does not necessarily mean that the bone is intact. The dura is also very echogenic. If the cyst is near the midline and one is unsure whether it has eroded through the skull, additional computed tomography (CT) or magnetic resonance (MR) imaging is indicated. These imaging methods can also demonstrate an encephalocele.

Dermoid cysts ( Fig. 5.31 , Fig. 5.32 , Fig. 5.33 , Fig. 5.34 , Fig. 5.35 , Fig. 5.36 , Fig. 5.37 ) in the neck region are usually in the midline. The tumor is smooth and oval or round, and its contents can be of any echogenicity. It can be homogeneous or mixed because of its contents, which may be fat, hair, blood, keratin, or something else. If a dermoid cyst is found between the hyoid bone and the thyroid gland, differentiation from a thyroglossal duct cyst is difficult. CT or MR imaging can show fatty content in a dermoid cyst; fat is not present in thyroglossal duct cysts.

Fig. 5.31 One-year-old girl with a swelling at the lateral eyebrow. An oval tumor (arrow) with hypoechoic content is present. The underlying bone is flattened but intact. Typical orbital dermoid cyst.
Fig. 5.32 Five-year-old girl with a swelling in the suprasternal notch. A sagittal image shows a well demarcated oval tumor (arrow) with almost homogeneous echogenicity. Pathologic examination showed a dermoid cyst.
Fig. 5.33 Two-year-old boy with a submental tumor located in the midline. Well delineated lesion with a thick wall. It is cystic with a large solid nodule. It was close to the hyoid bone. The patient was too young to follow instructions such as to stick out his tongue. The nodule is not compatible with a thyroglossal duct cyst. Pathologic examination showed a dermoid cyst.
Fig. 5.34 a, b Four-year-old girl with a small swelling just left of the midline. On (a) transverse and (b) sagittal images, ultrasound shows an almost round tumor anterior to the left lobe of the thyroid gland (arrows). It was believed to be a thyroglossal duct cyst, but on microscopic examination, it was compatible with a dermoid cyst.
Fig. 5.35 a, b Sagittal (a) and transverse (b) views of a swelling (arrow) in the suprasternal notch of a 4-year-old girl, present for 2 weeks. It was free from the skin and underlying tissue. It did not move when the patient stuck out her tongue. On pathologic examination, a dermoid cyst was found.
Fig. 5.36 One-year-old boy presenting with a firm smooth tumor at the suprasternal notch. Sagittal ultrasound image shows an anechoic cyst with some wall thickening just above the sternal manubrium. Pathologic examination showed an epidermoid cyst.
Fig. 5.37 Fourteen-year-old boy with a swelling on the right cheek. There was a bluish discoloration over the bump. Clinically, it was a vascular tumor. Ultrasound showed an oval tumor with homogeneous echogenicity and a hypoechoic rim. Color flow was absent. On pathology, an infected sebaceous cyst was found.

5.2.3 Hemangiomas and Vascular Malformations

Hemangiomas and vascular malformations are both endothelial malformations. Today, the classification of Mulliken is used. He described a division into hemangiomas and vascular malformations. The latter can be further divided into capillary, venous, arteriovenous, lymphatic, and mixed malformations and fistulas. In the case of vascular malformations, a separation into high-flow lesions and low-flow lesions is even more important. High-flow lesions have an arterial component. Low-flow lesions do not have an arterial component.

Hemangiomas are often called infantile hemangiomas because of the age at which they appear. They are small or absent at birth. They increase in size during the first year of life. Thereafter, they slowly decrease in size and can disappear, often leaving a fibrofatty scar. If they occur in places where their increasing size poses clinical problems, such as around the orbit or near the airway, treatment is necessary. For the past few years, β-blockers have been the first line of treatment.

On ultrasound, infantile hemangiomas in the infant are richly perfused tumors ( Fig. 5.38 and Fig. 5.39 ). Ultrasound can show their extent into deeper tissues. If there is any doubt about this, MR imaging is indicated. On color Doppler, the involution of a hemangioma is signaled by decreased perfusion of the mass.

Fig. 5.38 a, b Ten-week-old girl with a hemangioma at the right lateral neck. a A well demarcated echogenic tumor (arrowheads) is visible in the subcutis. No extension into the deeper layers is present. b On color Doppler, the lesion is richly perfused.
Fig. 5.39 a–c Four-month-old boy with a progressive swelling anterior to the left ear. On palpation, a mass was felt. a Ultrasound shows a lesion that involves almost the entire parotid gland. b The lesion shows abundant perfusion on color Doppler. c Magnetic resonance imaging demonstrates extension toward the parapharyngeal space. Note the large vessels (arrow).

Vascular malformations are present at birth and grow proportionally with the child. They can be asymptomatic or cause symptoms, sometimes at an older age. Ultrasound can show the extent of a lesion, but if this is unclear, MR imaging should be employed ( Fig. 5.40 and Fig. 5.41 ). Doppler ultrasound can demonstrate the presence of arterial Doppler signals and direct further imaging. If Doppler ultrasound shows arterial waveforms suggesting a high-flow lesion, angiography should be done to determine if transarterial embolization is feasible. If Doppler ultrasound shows a low-flow lesion, direct puncture under ultrasound can be done, followed by phlebography and, if possible, sclerosis. Excision is another therapeutic option.

Fig. 5.40 a, b Seventeen-year-old girl with a vascular malformation of the left masseter muscle, discovered at the age of 3 weeks. It was a lesion with high flow on ultrasound. No therapy was given. She returned after 10 years because of ridicule at school due to the swelling of her face. a Ultrasound shows an echogenic lesion in the lateral part of the masseter muscle (arrow). The normal right side (arrowhead) is shown for comparison. b T2-weighted coronal magnetic resonance imaging of the same lesion (arrow).
Fig. 5.41 a–d One-month-old girl with a swelling in the floor of the mouth, under the tongue. Ultrasound (a) did not show the extension of the vascular malformation into the parapharyngeal space (arrow, b) and mediastinum (arrowheads, c, d) seen on magnetic resonance imaging.

Vascular malformations, especially those with predominantly venous components, can be difficult to depict because they are easily compressed. Use a lot of gel and just touch the lesion lightly.

Lesions with mostly lymphatic components, also called lymphangiomas, cannot be easily compressed ( Fig. 5.42 , Fig. 5.43 , Fig. 5.44 , Fig. 5.45 ). In infancy, a multicystic form occurs, composed of innumerable small cysts. This lesion is often apparent at birth as a gross swelling of the neck and is also known as hygroma colli. In older children, lymphangiomas appear mostly in the posterior neck and consist of one or more larger cysts.

Fig. 5.42 a, b Two-year-old boy with a swelling in the right neck. Ultrasound (a) shows a multicystic vascular malformation. No perfusion was seen on color Doppler. The mass was treated with a sclerosing agent (arrow: needle tip) (b). (Courtesy of R. R. van Rijn, Academic Medical Center, Amsterdam, the Netherlands.)
Fig. 5.43 a,b Seven-month-old girl with a swelling in the right neck, deep to the sternocleidomastoid muscle, consistent with a vascular malformation (arrow). b One week after OK-432 injection, the lesion has increased in size. One year later, the lesion had decreased slightly in size.
Fig. 5.44 a, b Two-year-old girl with a swelling in the right lower neck. a A multicystic tumor was detected with ultrasound. b On magnetic resonance imaging (proton density fat-suppressed sequence), extension into the parapharyngeal space (arrowhead) and into the floor of the mouth was visible. Sclerotherapy of the lesion with OK-432 had limited success.
Fig. 5.45 One-year-old girl with a swelling in the right lower neck. A multicystic tumor (arrow) extends behind the larynx (arrowhead) to the left. After sclerotherapy with OK-432, the lesion involuted. Two years later, a recurrence was seen in the supraclavicular region. Unfortunately, no magnetic resonance imaging was done before the sclerotherapy.

Lymphangiomas can extend much farther than ultrasound shows. If there is any doubt about the extent of a tumor, additional MR imaging is indicated.

Surgery is the primary treatment for hygroma colli, but the operation can be difficult because the tumor has a tendency to infiltrate the deeper tissues (see Fig. 5.42 ). The form with larger cysts can be surgically removed, but aspiration and injection with a sclerosing agent is also done (see Fig. 5.43 , Fig. 5.44 , Fig. 5.45 ).

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Jun 9, 2020 | Posted by in ULTRASONOGRAPHY | Comments Off on 5 Neck
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