Diagnostic Ultrasound - Abdomen and Pelvis

Parovarian Cyst
TERMINOLOGY
Abbreviations
• Paratubal cyst
Definitions
• Cyst originating from wolffian duct in mesosalpinx or broad
ligament
IMAGING
General Features
• Best diagnostic clue
○ Unilocular cyst near but separate from ovary
– Often unilateral
• Size
○ Mean diameter: 40 mm (range: 15-120 mm)
• Morphology
○ Well-defined, round or oval cystic mass
– Rarely may be complicated by torsion or hemorrhage
Ultrasonographic Findings
• Adnexal cyst medial to ovary
○ Lack of follicles distinguishes from ovary
○ Separate from ovary
○ Usually does not indent ovary
• Unilocular in 95%
• Multilocular in 5%
○ May contain septa that are thin, smooth, complete
○ May represent multiple cysts on same side
• Fluid is anechoic in 91%
• Small, floating echoes (probably hemorrhage) in 9%
• Thin outer wall (< 3 mm)
○ Some with 2-5 mm papillae
Imaging Recommendations
• Best imaging tool
○ Transvaginal ultrasound
• Protocol advice
○ Study any adnexal mass from border to border
– Decide ovarian vs. extraovarian
□ Evaluate cyst characteristics
○ Study cyst mobility with vaginal probe
– "Split" sign or "pelvic slide test" (cyst moves separate
from ovary)
CT Findings
• Round or oval cystic structure, close but separate from
ovary
MR Findings
• Round or oval cystic structure, close but separate from
ovary
• Hypointense on T1WI and hyperintense on T2WI
○ If complicated by torsion or hemorrhage, may be
hyperintense on T1WI and have thick walls
○ If soft tissue component, consider neoplasm
DIFFERENTIAL DIAGNOSIS
Peritoneal Inclusion Cyst (PIC)
• Loculated, peritoneal fluid producing unilocular or
multilocular cystic mass
○ May be ovoid or irregular in contour
○ May contain internal echoes or septa
○ No perceptible walls
○ Surrounds normal ovary
Hydrosalpinx
• Tubular morphology with separate ovary
• Hyperechoic mural nodules common
True Ovarian Cyst
• Unilocular or complex
• Look for ovarian tissue at cyst borders
○ Inseparable from ovary
PATHOLOGY
Gross Pathologic & Surgical Features
• 98% benign serous cyst
• 2% with malignant features
○ Cystadenoma or cystadenocarcinoma
CLINICAL ISSUES
Presentation
• Most common signs/symptoms
○ Asymptomatic
– Found at time of imaging of pelvis for other reasons
○ Adnexal mass
• Other signs/symptoms
○ Torsion, growth, and malignancy are rare complications
Demographics
• Epidemiology
○ 10-20% of all adnexal masses
– Most common in 3rd and 4th decade
Treatment
• Surgery avoided if cyst < 5 cm and no papillae
DIAGNOSTIC CHECKLIST
Consider
• Often misdiagnosed as true ovarian cyst
Image Interpretation Pearls
• Do not assume every cystic adnexal mass is ovarian
• Correct diagnosis important to avoid surgery
• MR superior for identification of normal ovary when origin
of large lesion cannot be determined with ultrasound
SELECTED REFERENCES
1. Suzuki S et al: Two cases of paraovarian tumor of borderline malignancy. J
Obstet Gynaecol Res. 39(1):437-41, 2013
2. Damle LF et al: Giant paraovarian cysts in young adolescents: a report of
three cases. J Reprod Med. 57(1-2):65-7, 2012
3. Kiseli M et al: Clinical diagnosis and complications of paratubal cysts: review
of the literature and report of uncommon presentations. Arch Gynecol
Obstet. 285(6):1563-9, 2012
4. Laing FC et al: US of the ovary and adnexa: to worry or not to worry?
Radiographics. 32(6):1621-39; discussion 1640-2, 2012
5. Patel MD: Pitfalls in the sonographic evaluation of adnexal masses.
Ultrasound Q. 28(1):29-40, 2012
6. Moyle PL et al: Nonovarian cystic lesions of the pelvis. Radiographics.
30(4):921-38, 2010
Diagnoses: Female Pelvis
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