Scan reveals calcification
with fat contents within the neck mass.
the neck, nasopharynx, pharynx, and oral cavity are usually large, bulky
masses that are clearly evident and recognized at birth. Many of these
are diagnosed at routine prenatal ultrasound examinations. The primary
differential diagnostic considerations for a large neck mass, either in
a fetus or an infant, include cystic hygroma and congenital cysts of branchial
cleft or thyroglossal duct origin.
The majority of extragonadal teratomas, including those of the head and
neck, manifest during childhood, although they represent less than 5%
of all pediatric neoplasms. Some authors have reported a bimodal distribution
for craniofacial teratomas, with the biologically and histologically benign
lesions seen in infants and children and malignant teratomas seen in older
children and adults. In a review of the literature, Jordan and Gauderer
reported that only 10.6% of all cervical teratomas occurred in adults
but 69% were malignant, compared with only 2.5% that were malignant in
patients under 18 years of age.
A teratoma can be suspected when a multiloculated lesion with focal areas
of low attenuation and high signal intensity (representing lipid) is seen
on CT and T1-weighted MR images, respectively. Radiologically evident
lipid may be scattered throughout the mass, rather than forming a single,
large collection or fat-fluid level that might suggest a dermoid inclusion
cyst. The developmental cysts of the branchial cleft and thyroglossal
duct are also more often unilocular, with only a thin rim of enhancement,
and do not contain fat. Occasionally, these cysts appear septated and
therefore mimic a multiloculated teratoma. Thyroglossal duct cysts tend
to be oblong or roughly tubular, oriented vertically along the path of
the normal embryologic migration of those structures. Within the tongue,
they are usually in the posterior one-third or the base. The lingual teratoma
illustrated in resembles a thyroglossal duct cyst, but it is multilocular
and somewhat more anterior within the tongue muscles than the embryologic
course of the thyroglossal duct.
Ashok Raghavan, Manipal Hospital, Bangalore