| Discussion: PEDIATRIC
NECK MASSES (See cases 4202476, 4202528, 4202602, 4202667)
55% are congenital, 27% primarily inflammatory, 11%
neoplastic.
INFLAMMATORY mass differential includes:
Reactive
lymphadenopathy: present in 40%
of infants and 55% of healthy children. Cervical node size
not
greater than 1 centimeter is normal in children under 12.
Viral/bacterial
lymphadenitis: tender fluctuant nodes.
Granulomatous disease
(mycobacterial, sarcoid, fungal, toxoplasmosis, cat-scratch disease,
etc)
Other miscellaneous
disease: AIDS, Kawasaki disease, sialadenitis, abscess,
etc.
NEOPLASTIC mass differential includes:
Benign: lipoma,
fibroma/neurofibroma, lipoblastoma, paraganglioma, salivary gland
tumor, goiter.
Malignant: Hodgkin
disease, non-Hodgkin
lymphoma, thyroid cancer, rhabdomyosarcoma, neuroblastoma,
fibrosarcoma.
CONGENITAL NECK MASSES:
THYROID DUCT CYST
Epidemiology:
TGDCs are the most common mass
found in the
midline of the neck in children, occuring in about 7% of
children.
Etiology:
The thyroid gland forms as a
diverticulum from
the floor of the pharynx (tuberculum impar) at a site that later
becomes the foramen cecum of the base of the tongue. The thyroid gland
then forms 2 lobes and descends along a hollow canal called the
thyroglossal duct in the midline of the neck. During the descent, the
thyroglossal duct passes in close proximity to the developing hyoid
bone. The thyroglossal duct normally involutes; however, when
involution does not occur, the potential for development of a TGDC
increases. Arrest in the normal descent of the gland results in
ectopic
thyroid tissue.
Many patients with a TGDC have
some thyroid
tissue in the cyst; therefore, thyroglossal duct anomalies might be a
better term for their condition
Clinical presentation:
Thyroglossal duct cysts
usually present in the
first ten years of life, but may be found in older children or even
adults.
Cystic mass near midline near
the hyoid
bone. Suprahyoid thyroglossal duct cysts lie in the midline.
Infrahyoid thyroglossal duct cysts may be off midline but usually are
not as lateral as branchial cleft cysts.
Thyroglossal duct cysts move
upward during swallowing and protruding the tongue
May be inapparent until after
a URI, when it will appear in the front of the neck.
Often has a small tract
connecting it to the tongue base.
Complications:
May become secondarily
infected, and there is a risk of papillary carcinoma in
adults.
Hypothyroidism may occur if
the resected cyst contained all or most of the patient's thyroid
tissue.
BRANCHIAL CLEFT CYST
Embryology
Baer first described the
branchial apparatus
in 1827. The branchial arches begin to develop during the second week
of gestation. During the fourth week of fetal development, 5 ridges,
known as branchial arches, form on the ventrolateral surface of the
embryonic head. Each arch contains mesoderm from which cartilage,
muscle, and bone develop. Each arch is separated from the other arches
by an external cleft of ectodermal origin. Each arch also has an
internal pouch of endodermal origin and an associated cranial nerve,
artery, and cartilage. The second arch grows caudally and, ultimately,
covers the third and fourth arches.
First branchial cleft forms
some ear
structures (tragus, helix, cymba concha. Incus, malleolus), the lower
lip, mandible, muscles of mastication, and anterior tongue. Second
(hyoid) forms the antihelix, antitragus, anc concha nd the
styloid, stylohyoid, and lesser hyoid cornu. The third branchial arch
forms body of hyoid and tongue base. The 4th, 5th, 6, form the
thyroid,
cricoid, and arytenoid cartilages.
Etiology:
The second branchial cleft accounts for 95% of branchial anomalies.
Third branchial cleft cysts are rare. Fourth branchial cleft cysts are
extremely rare.
An estimated 2-3% of cases are
bilateral.
A tendency exists for cases to
cluster in families.
No ethnic or sexual
predilection has been reported.
Branchial cysts are twice as
common as either branchial sinuses or fistulas.
Clinical Presentation:
Patients most commonly present
with a palpable neck mass.
Patients also may present with
mass effect such as respiratory compromise.
Cyst types:
First branchial
cleft: Type I are near
the external auditory canal. Most commonly inferior and posterior to
the tragus but may also be in the parotid gland or at the angle of the
mandible. Type II cysts are associated with the
submandibular
gland or found in the anterior triangle of the neck.
Second branchial
cleft: Most frequently
identified along the anterior border of the upper third of the
sternocleidomastoid muscle, adjacent to the muscle, but may present
anywhere from the skin of the lateral neck, between the internal and
external carotid arteries, and into the palatine tonsil .
A third branchial fistula
extends from the
same skin location as a second branchial; however, a third branchial
fistula courses posterior to the carotid arteries and pierces the
thyrohyoid membrane to enter the larynx.Third branchial cleft cysts
occur anywhere along that course (eg, inside the larynx), but are
characteristically located deep to the sternocleidomastoid muscle.
A fourth branchial fistula
arises from the
lateral neck and parallels the course of the recurrent laryngeal nerve
(around the aorta on the left and around the subclavian artery on the
right), terminating in the pyriform sinus; therefore, fourth branchial
cleft cysts arise in various locations, including the
mediastinum.
Treatment:
Complete surgical resection is
the treatment
of choice and results in a good prognosis. Patients with infected
cysts
receive a full course of antibiotics before surgery to decrease the
risk of recurrence and persistent fistula.
Alternative treatments, such as percutaneous sclerotherapy, remain
unproven.
Complications include secondary infection and branchial cleft cyst
wall
carcinoma. Complications of surgical treatment include
recurrence, formation of a persistent fistula, and damage to the
cranial nerves.
Imaging:
On cross-sectional imaging, a branchial cleft cyst can be confused most
easily with a cystic hygroma (lymphangioma).
MRI of the neck is the preferred examination for a suspected branchial
cleft cyst. Branchial cleft cysts have high signal intensity on
T2-weighted images. On T1-weighted images, the signal intensity is
usually low, but prior infection can provoke proteinaceous debris that
increases the T1 signal intensity. Infiltration of surrounding tissue
may indicate lymphangioma. The findings distinguish cystic tissue from
solid masses and enables evaluation of the extent of the lesion. MRI
provides anatomic information that relates the mass to the surrounding
structures. MRI can be used to evaluate for concurrent anomalies.
Uninfected branchial cleft cysts should not be enhancing. MRI can be
used to distinguish a solid parotid mass from a first branchial cleft
cyst.
Ultrasonography may confirm the cystic nature of a mass, but it is not
as useful as MRI.
Contrast-enhanced CT reveals a well-defined, nonenhancing mass of fluid
attenuation in a characteristic location.
LYMPHANGIOMA or CYSTIC HYGROMA
A lymphangioma is the result
of an abnormal
collection of lymph channels in the body. During
fetal
development connections may occur causing cysts made up of these
channels to grow. Large extensive collections of these are known as
lymphangiomas or cystic hygromas. They grow steadily with the child
and
usually surround normal muscles, blood vessels, and nerves. These
cysts
can involve the neck, oral cavity, face and airway. They can also
extend into the chest. Lymphangiomas grow around normal
muscles,
blood vessels, and nerves. They may become quite extensive and cause
significant cosmetic deformities and functional disabilities. They may
interfere with swallowing, breathing, or speaking.
Currently, most researchers agree that LM are not neoplastic and have
adopted the term "lymphatic malformation" to emphasize this
fact.
While benign, they continue to grow and many times cannot be
completely
removed without sacrificing an important normal structure.
Etiology:
Two major theories of the
development of the
lymphatic system have been proposed to explain the origin of
LM:
theories of lymphatic development from either five primitive venous
sacs (Sabin) or mesenchymal clefts in the venous plexus reticulum
(McClure and Huntington); either way, LM develop from sequestration or
congenital blockage of the developing system.
The most popular
classification system was
proposed by Landing and Farber in 1956. Lymphangioma simplex is
composed of three walled lymphatic channels. Cavernous lymphangioma
consists of dilated lymphatic spaces with increased fibrous advance.
They also tend to invade surrounding tissue. Cystic lymphangioma is
made up of endothelial lined cysts varying in size from mm to several
cm. Histologically, there is no significant difference between the
various clinically described types of lymphatic malformations
according
to Batsakis.
Hemangioma often forms mixed
tumors with lymphangioma and can appear anywhere in the neck.
Epidemiology
LM are considered rare
entities, as low as 5
new cases per 3000 first admissions per year, or 1 in 4000 live
births.
In general, 50-60% of LM
present at birth and
80-90% present by 2 years of age. In the adult population 45% cervical
LM occur in the 40-60 year age range.
In most series, the head and
neck are the most
common sites for LM followed by the trunk, axilla, and extremities.
In the head, the oral cavity
and face area are
the most common sites. In the neck, the posterior triangle is often
quoted as the most common site. However, many series have reported no
difference between the anterior and posterior triangles. There does
seem to be a predominance of right sided lesions. Laryngeal
involvement
is not uncommon.
Clinical Presentation:
Because of their size,
lymphangiomas are
usually visible as a large compressible mass. Those not noticed at
birth are recognized before most children reach their second
birthday. These lesions are first evaluated by physical
examination, as above. The mass is soft, flaccid, fluctuant,
with
a multilobulated consistency. It may
transilluminate.
The site of the lesion
determines the
symptomology. Many patients have no symptoms other than a soft tumor
mass. Oral cavity and laryngeal involvement can produce stridor,
dyspnea, and feeding difficulties.
Rapid expansion can occur with
hemorrhage into
the cyst or infection. Trauma can be associated with rapid development
of cellulitis, and significant swelling of the LM. In cervicofacial
LM,
this can lead to life threatening airway obstruction.
LM may rarely spontaneously
regress or may regress with steroids
Imaging:
Imaging studies such as USG,
CT, and MRI can
be useful in treatment planning. In particular, CT and MRI are most
useful in determining proximity to vital structures and mediastinal
involvement preoperatively.
Magnetic Resonance imaging
(MRI) is the
imaging study that gives the best information regarding the extent and
location of the cystic hygroma. CT scans may also be used to
help
fully realize the extent of the cyst. See the hemangioma
section,
below.
Treatment may be medical, using sclerosing agents, or
surgical.
Additionally a tracheotomy may be needed to secure the
airway.
There is a report of using
OK-432 an immune modulator, with resulting regression.
Radiation therapy was used in
the past, but is
characterized by a high failure rate, and risk of lymphangitis,
lymphedema, and lymphangiosarcoma.
Laser treatment is popular for
the treatment
of oral cavity and airway lesions. The advantages are less post-op
edema, less tissue trauma and less bleeding. Multiple
treatments
are often necessary.
Surgical extirpation is
usually the treatment of choice in cervical and facial LM.
Associations
Many clinical entities have
been reported to
be associated with LM, including congenital glaucoma Klippel-Trenauny
syndrome, Noonan's syndrome, Down syndrome, andTurner's
syndrome.
BRONCHOGENIC CYST
Etiology:
Result of anomalous
development of ventral foregut.
May thus be found anywhere
along the
tracheoseophageal course, perihilar, or intraparenchymal, with
predilection for carinal area. Also rarely in distant
sites.
Epidemiology:
Relatively rare but still the
most common cystic lesion of the mediastinum.
6-15% of primary mediastinal
masses.
No sex predilection.
More than 50% are diagnosed in patients over 15 years old.
Usually single but may be
multiple
Clinical presentation:
More than half of patients are
asymptomatic but can cause airway compromise.
Chest pain and dysphagia are
most common adult
symptoms; in children, esophageal or airway compression is most common
presentation. 70% of children were asymptomatic in one
report
because 75% of theiir cysts were in a critical area around the carina,
more commonly than in adults.
May cause partial obstruction
and resultant
emphysema. May also cause SVC syndrome, pneumothorax,
pleurisy,
pneumonia, tracheal compression.
Should be considered in
patient with recurrent pulmonary infections.
Complications:
Airway compromise.
May form fistula with airway;
Rhabdomyosarcoma and
adenocarcinoma have bee reported.
Gastric mucosal cysts may
hemorrhage,
Abdominal cysts may cause
compression or infection.
Imaging:
In CT or MRI, finding of a
cystic lesion at
the level of the carina is most frequently suggestive of bronchogenic
cyst.
CT: smooth-bordered
thin walled cyst,
may contain secretions, pus, or blood. May be
calcifications.
MRI: Homogenous
moderately-to-brightly
T2-hyperintense mss. T1 is variable due to protein
content.
LARYNGOCELE
An air sac connected to the larynx through the laryngeal ventricle,
often bulging outward into the tissue of the neck, especially during
coughing.
May be found in players of wind instruments (and glass
blowers?).
High pressure within the larynx pushes mucosa through the thyrohyoid
membrane resulting in a reducible tense mass in the neck, which recurs
with sneezing, blowing the nose, etc.
THYMIC CYST
The thymus develops from the
inferior part of
the third pharyngeal pouch and migrates to the mediastinum. Parts may
remain in the neck and the thyroid gland and may form an ectopic
thymus; thymic cysts may develop from remnants of the thymopharyngeal
duct.
Thymic cysts are rare lesions
found in the
mediastinum or the neck. In children, the cervical lesions present as
painless swellings. These lesions are most often found posterior of
the
lateral lobe of the thyroid, more often on the left side. They are
1-15
cm in diameter.
Imaging: Multilocular thymic cysts typically manifest on CT
as
unilocular or multilocular cystic thymic masses, often with
soft-tissue
attenuation components. CT cannot be used to distinguish neoplastic
from nonneoplastic soft-tissue components.
HEMANGIOMA
A hemangioma is an abnormal
growth of blood
vessels that are formed before or shortly after birth. They can be
very
small (pinpoint) or grow to be quite large. They need to be
distinguished from vascular malformations (abnormal connections
between
blood vessels) because treatment is different.
Vascular skin lesion can be divided into congenital and acquired
lesions:
Congenital:
Vascular
malformations—errors in embryonic vascular formation. Do not
proliferate but du gradually enlarge. May be classified based
on
type of blood flow into slow-flow (capillary, venous, lymphatic),
high-flow (arterial), or combined. Lymphatic malformations
may be
divided by lumen size into microcystic (previously "lymphangioma")
macrocystic (previously "cystic hygroma") and combined.
Acquired: Most
significantly
hemangioma. Benign but potentially destructive.
Undergo
proliferating and involutional stages. Pyogenic granuloma is
a
second type of acquired vascular lesion; as are senile angiomas, AVF,
spider angioma, and Kaposi sarcoma.
Clinical presentation:
Presentation is dependent on type and extent of lesion.
History
should include: (1) was the lesion present at
birth? (2)
did proportional or disproportional growth of the lesion occur? (2)
did
an involution phase occur? (4) did an episodic enlargement
occur?
Hemangiomas may look like
small red pimples on
the skin, large bulging bluish-red masses protruding from the forehead
or eyelid, or soft compressible bluish masses in the neck.
Hemangiomas usually start to
grow larger
shortly after birth (proliferative stage) reaching a peak at 18 months
to 2 years of age. At that point, most hemangiomas will start to
shrink
(involute). This process may take several years.
Hemangioma often forms mixed
tumors with lymphangioma and can appear anywhere in the neck.
Imaging:
Magnetic resonance imaging
(MRI) is used to
diagnose hemangioma. It demonstrates extent of the lesion
and
differentiates between types of malformation.
Hemangioma will be very T1-hyperintense, and will be T2-hyperintense
and enhancing during proliferative phse but T2-hypointense and less
enhancing during
involution.
Lymphatic malformation will be T1-hyperintense and middling T2
intensity, with no enhancement. Lymphatic malformations have
typically a solid appearance with low T1 intensity, equal to that of
venous VM's and less intense than that of hemangiomas.
Venous malformations are
T1-hyperintense, middle T2 intensity, and brightly
enhancing.
Contrast-enhanced T1 images
show very low
central intensity with typical rim enhancement of the lymphatic
lesion.
Ultrasound may differentiate
low-flow from high-flow lesions.
CT can detect calcifications, which are present in low-flow combined
venous lymphatic lesions.
DERMOID CYST
Etiology:
Result of sequestration of
skin along the lines of embryonic closure.
Lined by epidermis with
epidermal appendages, usually fully mature.
Usually midline along a line
from the middle
of the forehead to the bottom of the neck. Can be lateral,
around
the forehead and eyes.
Clinical presentation:
Congenital mass usually
visible at birth,
localized on head, neck, or trunk. Also in the mouth, penis,
and
testes.
The presence of a hair collar
sign around a
suspected dermoid cyst might indicate cranial dysraphism, such as that
seen in a cutaneous ectopic brain.
Often adherent to periosteum
when on the head and can cause pressure related erosion of the bone..
A dermoid cyst may present as
a small,
painless swelling on the face, scalp, nose, or neck. They can range in
size from 1 to 4 cm.
Imaging: CT is useful to look for any part of the dermoid
cyst
that may extend into bone, particularly of nasal dermoid cysts.
Dermoid
cysts generally have low attenuation because of their fat
content.
Complications:
malignant transformation, infection.
SEBACEOUS CYST—you know about this one.
TERATOMA—you know about this one.
|
12 YEAR OLD BOY WITH NECK MASS.
