We analyzed retrospectively a total of 30 cases evaluated by ultrasonography,
computer tomography (CT) and magnetic resonance (MR),
highlighting the main semiological elements that support the diagnosis.
Ultrasound findings (fig.
1-7)
•the imaging modality for initial diagnose
•cystic lesion with a mural hyperechogenic nodule called Rokitansky nodule with acoustic shadow; Rokitansky nodule (dermoid plug) = hair and/or sebaceous components (plump of hair that absorbes and reflects sound at US)
• the tip of the iceberg sign (diffusely or partially echogenic mass with posterior sound attenuation; due to sebaceous material and hair within the cyst lesion,
only superficial part of
the cyst is seen);
"dermoid mesh" sign or dot-dash pattern (diffuse or regional shining echoes/ hyperechoic lines and dots);
•tendency towards sedimentation occurs (fluid-fluid level); without Doppler; when Doppler is present -> malignant disruption should be excluded;
•intense acoustic shadowing within cyst owing to calcifications(tooth components)
¾ of the dermoid cysts show ≥2 of the above characteristics,
while no other adnexal mass presents more than one of these features.
CT findings (fig.8-18)
hight sensitivity in diagnosis
•most tumors measure 4-17 cm (average size: 8cm),
septa may be thin and the wall of the cyst,regular and not thick (2-5 mm);
•interface between two liquid components,
in the Rokitansky nodule or like a fat-fluid level;fat attenuation within a cyst high specific for mature ovarian teratoma; tufts of hair;
•Rokitansky nodule: it is quite common to be found; it is seen as a protuberance projecting into the lumen of the cyst with a regular border and an oval shape; its average diameter is 28 mm (from 10 to 45 mm);
Calcifications/ tooth components most often are found within mural nodules,
but they also may be seen in cystic septa or walls.
MR findings (fig.19-26)
•exquisitely sensitive to fat components
•indicated to differentiate fat from blood
•enhancement is able to identify solid invasive components in malignant disruptions processes
sebaceous component: high signal intensity on T1-weighted images (FAT-SAT sequence will suppress the high signal of fat in teratomas differentiating them form hemorrahagic lesions)
Possible complications
- ovarian torsion
- rupture
- malignant transformation
- superimposed infection
Differential diagnosis
- haemorrhagic ovarian cyst
- endometrioma
- pedunculated lipoleiomyoma of the uterus
- immature teratoma
- ovarian serous/ mucinous cystadenoma/cystadenocarcinoma