Diagnostic Ultrasound - Abdomen and Pelvis

Ovarian Teratoma
Diagnoses: Female Pelvis
• Large bowel may contain echogenic feces mimicking
teratoma
• Colon does not undergo peristalsis as much as small bowel
• May require repeat exam or alternate modalities, such as
MR, to clarify
PATHOLOGY
Gross Pathologic & Surgical Features
• MCT
○ Mature tissues of endodermal, mesodermal, and
ectodermal origin
○ 88% unilocular, fat content liquid at body temperature,
semisolid at room temperature
○ Rokitansky nodule: Nodule protrudes into cyst cavity
– Most hair arises from nodule; if teeth/bone present,
will be in this protuberance
○ 31% of MCTs contain teeth
• IT: Often show capsular perforation
• Monodermal teratoma
○ Thyroid tissue in struma ovarii
– Amber-colored thyroid tissue with hemorrhage,
necrosis, fibrosis; no fat present
○ Neuroectodermal tissue in carcinoid tumor
– Unlike MCT, these occur in postmenopausal women
Microscopic Features
• MCT
○ Scant mitotic activity, no cytologic atypia
○ Walls lined by squamous epithelium
○ Malignant degeneration may give rise to squamous cell
cancer, malignant melanoma, sarcoma
• IT: Contain embryonic/immature tissues as well as mature
line seen in MCT
○ Amount of yolk sac tumor correlates with stage, grade,
and recurrence rate
○ Overgrowth of immature neural elements → primitive
neuroectodermal tumor
○ May rupture: Reported in < 1% of cases
○ May act as lead point for adnexal torsion
○ Rarely undergo malignant degeneration
– ~ 1-3%
– Squamous cell carcinoma (most common),malignant
melanoma, sarcoma
– Older patients (6th-7th decades)
– Tumor diameter > 10 cm
– Rapid growth
○ Rarely present with prolactinemia, hypercalcemia,
autoimmune hemolytic anemia, erythrocytosis, or
paraneoplastic syndrome (secondary to NMDA receptor
antibodies)
• IT
○ Primitive neuroectodermal tumors have poor prognosis
○ IT treated with chemotherapy may "retroconvert" (i.e.,
take on MCT appearance)
– May remain stable for long duration
Treatment
• Surgical resection for definitive diagnosis and to avoid
potential complications
• Ovarian cystectomy
○ With laparoscopy or laparotomy
○ Care taken to prevent cyst rupture and copious irrigation
performed to avoid peritonitis
DIAGNOSTIC CHECKLIST
Consider
• "Tip of the iceberg" sign prevents accurate estimation of
size
○ Size may be important to operating surgeon
Image Interpretation Pearls
• Rokitansky nodule (dermoid plug) is diagnostic
• 10-20% MCTs are bilateral
○ Look for small contralateral tumor
822
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ MCTs are often asymptomatic
– Most common ovarian tumor
□ 50% of all ovarian tumors
– Most common incidentally discovered ovarian mass
during cesarean section delivery
Demographics
• Age
○ MCT: Mean age at presentation is 30 yrs.
– Most common ovarian mass in children
○ IT: 0-20 years
• Epidemiology
○ Most commonly excised ovarian neoplasm
○ 95% ovarian germ cell tumors are MCT
Natural History & Prognosis
• MCT
○ 10-20% bilateral
○ Often asymptomatic
SELECTED REFERENCES
1. Young RH: Ovarian tumors and tumor-like lesions in the first three decades.
Semin Diagn Pathol. 31(5):382-426, 2014
2. Baser E et al: Adnexal masses encountered during cesarean delivery. Int J
Gynaecol Obstet. 123(2):124-6, 2013
3. Hursitoglu BS et al: A clinico-pathological evaluation of 194 patients with
ovarian teratoma: 7-year experience in a single center. Ginekol Pol.
84(2):108-11, 2013
4. Yun NR et al: Squamous cell carcinoma arising in an ovarian mature cystic
teratoma complicating pregnancy. Obstet Gynecol Sci. 56(2):121-5, 2013
5. Fossey SJ et al: Sclerosing encapsulating peritonitis secondary to dermoid
cyst rupture: a case report. Ann R Coll Surg Engl. 93(5):e39-40, 2011
6. Alotaibi MO et al: Imaging of ovarian teratomas in children: a 9-year review.
Can Assoc Radiol J. 61(1):23-8, 2010
7. Choudhary S et al: Imaging of ovarian teratomas: appearances and
complications. J Med Imaging Radiat Oncol. 53(5):480-8, 2009
8. Saba L et al: Mature and immature ovarian teratomas: CT, US and MR
imaging characteristics. Eur J Radiol. 72(3):454-63, 2009
9. Park SB et al: Imaging findings of complications and unusual manifestations
of ovarian teratomas. Radiographics. 28(4):969-83, 2008