Diagnostic Ultrasound - Abdomen and Pelvis

Ovarian Teratoma
Diagnoses: Female Pelvis
TERMINOLOGY
• Mature cystic teratoma (MCT) = dermoid cyst
• Immature teratoma (IT)
• Monodermal teratoma in which 1 cell line predominates
IMAGING
• Mature cystic teratomas have a variety of appearances
○ Heterogeneous cystic ovarian mass with echogenic
shadowing mural nodule (Rokitansky nodule) on US
○ ± fat-fluid level
○ Highly echogenic focus/foci with distal acoustic
shadowing represent teeth
○ Hair within mucin creates characteristic dot-dash-dot
appearance
• Fat-containing adnexal mass is diagnostic on CT
TOP DIFFERENTIAL DIAGNOSES
• Hemorrhagic cyst
• Endometrioma
KEY FACTS
• Bowel
PATHOLOGY
• Mature tissues of endodermal, mesodermal, and
ectodermal origin
• 88% unilocular, fat content liquid at body temperature,
semisolid at room temperature
CLINICAL ISSUES
• Most common ovarian tumor
• 10-20% bilateral
• Rarely undergo malignant degeneration
• Rupture in < 1% of cases
• May act as lead point for adnexal torsion
DIAGNOSTIC CHECKLIST
• Rokitansky nodule (dermoid plug) is diagnostic
(Left) Dermoids may be mostly
cystic, with linear floating
echoes consistent with hair
ſt. The echogenic shadowing
Rokitansky nodule along
the periphery is diagnostic for
a dermoid. (Right) Ultrasound
shows that this dermoid has a
more heterogeneous
appearance due to differing
fat ſt and echogenic fluid
content . The Rokitansky
nodule is present as well.
(Left) Within the same mass
(calipers), there may be areas
of highly echogenic semisolid
fat ſt, with anechoic areas of
more liquid fat st. (Right)
Axial CECT in the same patient
shows the layering areas of fat
density in the left ovarian
dermoid ſt. A smaller dermoid
is also present in the right
ovary . 10-20% of dermoids
are bilateral.
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