Diagnostic ultrasound ( PDFDrive )

1664 PART V Pediatric Sonography
efective in 95% of children. 49 If head tilt persists, muscle release
or tenotomy is performed to prevent development of signiicant
craniofacial asymmetry and scoliosis. 5
Masses
Pilomatricoma
Pilomatricomas (previously called “pilomatrixomas”) are benign
neoplasms arising from the hair follicles. 198 hey are the second
most frequently resected mass in the head and neck in children,
ater lymph nodes. 198 However, pilomatricomas are infrequently
imaged because diagnosis is oten made clinically. Imaging is
oten requested when the clinician is unfamiliar with the diagnosis
or the lesion is in the preauricular region and needs to be excluded
from an intraparotid mass or branchial apparatus remnant. 198,199
hese lesions typically occur in the head and neck in children
younger than 10 years, with a smaller peak occurring in the
sixth and seventh decades. 199 Multiple pilomatricomas can be
seen in the setting of Gardner syndrome, myotonic dystrophy,
Steinert disease, Turner syndrome, and sarcoidosis. 199 Clinically,
the lesions are irm nodules attached to the skin and are freely
mobile over the subcutaneous tissues. On ultrasound, these lesions
are frequently well-deined, hypoechoic lesions with mild internal
heterogeneous echogenicity, speckled or chunky internal calciications,
and hypoechoic rim. he lesions may have internal vascularity
demonstrated by spectral Doppler (Fig. 48.60). Rarely, when
the lesion has ruptured, the mass has an irregular heterogeneous
sonographic appearance, indistinguishable from other subcutaneous
lesions. 200,201 here may be some perilesional hypoechogenicity,
which is found to correlate with perilesional inlammation. 202
Complete surgical resection is curative.
Congenital Infantile Myoibromatosis
Congenital infantile myoibromatosis, although rare, is the most
common ibrous tumor in the neonate and infant. he cause is
unknown, although some familial cases have been reported. 203,204
Histologically, these lesions are composed of well-circumscribed
nodules of plump spindle-shaped cells with staining characteristics
intermediate between smooth muscle cells and ibroblasts. Oten,
there is central necrosis with focal calciications. 203 hese masses
can occur in the skin, muscle, bone, or viscera or intracranially.
203,205,206 Infantile myoibromatosis lesions almost exclusively
afect infants and young children, with 88% occurring before 2
years of age. 203 Over half of the lesions are identiied in the
neonatal period, and some cases are diagnosed prenatally. 203,207
he World Health Organization (WHO) classiies congenital
infantile myoibromatosis into three types: the solitary type, also
called “infantile myoibroma”; the multicentric form without
visceral involvement; and the multicentric form with visceral
involvement. 203,206 he solitary infantile myoibroma is more
common in males (69%) and frequently occurs in the head,
neck, and trunk. he multicentric form is more common in
females (63%). he solitary form of infantile myoibromatosis
and the multicentric form without visceral involvement generally
have a good prognosis, and recurrence is rare. Surgical excision
is the treatment of choice when feasible; chemotherapy is used
in inoperable cases. Some cases may show spontaneous
regression. 203
On ultrasound, the lesions oten show a lobulated heterogeneous
appearance with central anechoic and hyperechoic
structures (Fig. 48.61). hick septations may separate the
anechoic regions. he lesions are typically hypovascular. 205
CT and MRI are useful in assessment of disease extent and
bone and sot tissue involvement and to screen for additional
lesions.
Other, less common ibrous lesions that can occur in the head
and neck include nodular fasciitis and inlammatory myoibroblastic
tumor. hese lesions have a nonspeciic sot tissue mass
imaging appearance and require additional imaging and biopsy
for deinitive diagnosis.
Malignant Neoplasms
Malignant neoplasms of the head and neck represent 12% of all
childhood cancers. Lymphomas and sarcomas encompass 50%
A
B
FIG. 48.60 Pilomatricoma. Seven-year-old girl with right scalp bump for 4 months. (A) Gray-scale ultrasound image shows a well demarcated
heterogeneous hypoechoic lesion with internal echogenic foci. (B) Color Doppler image shows presence of internal vascularity within the lesion.