Chairman, Division of Clinical Support ServicesSenior consultant radiologist Department of Diagnostic and Interventional ImagingKK Women’s and Children’s Hospital

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How to assess an ovarian cyst for malignancy?<Insert cover image here>

Adj A/Prof Ong Chiou Li

Learning objectives

• The normal ovary

• Types of adnexal masses

• Ultrasound evaluation of adnexal masses

• Features of physiological ovarian structures

and pathology

• Differentiating benign from malignant

Cyclical change in ovaries

• Follicular development

– Follicular phase• Antral follicles 2-4mm

• Dominant follicle 10mm (9-6 days prior to luteal surge)

– Ovulation• 20 – 24mm ( max diameter 15-30mm)

– Luteal phase

• Variation in ovarian volume

6 weeks

Corpus luteum

• Luteal phase

• Wall is slightly thicker and slightly

echogenic

• Hypervascular wall

• May haemorrhage and present with

complex appearances

• May simulate ectopic pregnancy

“Lace-like, fishnet appearance”

-Fibrin strands

Septa

Follow-up

“Solid-looking haemorrhagic cyst”

Functional ovarian “cysts”

• Women of child bearing age

• Usually unilocular and anechoic

• Thin-walled

• Less than 3cm, but can be larger

• Stimulated ovaries

• Resolves with ovulation

• May persist

Left ovary

Ovarian hyperstimulation syndrome

Adnexal masses

• Ovarian

– physiological/pathological

• Non-ovarian

– Uterus

– Bowel

– Lymph nodes

– Tubal

– Urinary tract

– Others – e.g. peritoneal inclusion “cyst”

Ovarian cysts

• Functional “cysts” – cyclical change

• Drugs

• Benign cysts

– Non-neoplastic cysts

– Neoplastic

• Malignant cysts

Seen on Day 2

Ultrasound follow-up

C - Fimbrial cyst

C

Simple cysts

• Up to 10 cm, any age ( risk of malignancy less

than 1%)

• Premenopausal, cysts up to 3cm considered

physiological, no follow-up required

• >3cm up to 5cm, likely benign, no follow-up

• Greater than 5cm, up to 7cm, annual follow-up

• More than 7cm, usually require further imaging

(MRI or surgery)

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Levine et al. Society of Radiologists consensus statement of Radiology 2010

Ultrasound evaluation of adnexal masses

• Location (ovarian / extraovarian)• Size• Morphological assessment

– Wall thickness, septation, internal echoes, solid areas, papillary structures, echogenicity, shadowing

• Colour / spectral Doppler– Colour morphology– Vessel location– Diastolic notch– Analysis of waveforms : RI / PI

Endometrioma

• Predorminantly cystic

• Single or multiloculated

• Diffuse low level echoes or anechoic

• May be associated with hydrosalpinx

Endometriotic cysts

Small dermoid cyst

Mature cystic teratoma

• Benign germ cell tumour

• Usually asymptomatic

• Echogenic contents +/- shadowing

• Echogenic strands and dots

• Fat-fluid level

Ovarian neoplasms

• Epithelial

• Germ cell

• Sex cord-stromal tumours

• Metastases

Epithelial neoplasms

• 60% of all ovarian neoplasms

• 85% of malignant neoplasms are epithelial

• Types of tumours– Serous (50%)

– Mucinous, endometrioid (20% each)

– Clear cell (10%)

– Undifferentiated (<5%)

Mucinous tumour of the ovary

20-year-old with LIF pain Borderline mucinous tumour

35-year-old

Clear cell ca in endometrioticcyst

Non-epithelial tumours

• Germ cell tumours

– Teratomas, dysgerminoma, endodermal sinus

tumours

• Sex cord tumours (1-2% of ovarian

malignancies)

• Metastatic (bowel, breast, melanoma, etc)

Ovarian fibroma

Thickened endometrium in post-

menopausal woman

Hyperplasia, polyps or

neoplasia?

Granulosa cell

tumour

Benign features

• Unilocularity

• Thin wall

• Few septa

• Absence of papillary projections

• Crescent sign1,2

1. Kushtaqi P, Kulkarni KK. SMJ 2008

2. Hillaby K, et al. UOG 2004

Morphological assessment

• 1:178 unilocular cysts ( >40 years) is

malignant.

Malignant cyst contained papillary

excresence.

Granberg et al ’89 (1017 adnexal specimens)

Morphological assessment

• 1.1% incidence of malignancy in simple cysts in

women > 40 years (Osmers et al ’96)

• Unilocular and bilocular cysts – identical risk

• 36% malignancy in multiloculated cysts and those

with complex solid masses (Andolf ’89)

• Risk of malignancy very low for isolated unilocular

simple cysts (Modesitt, 2003, n=2763)

Differentiating benign from malignant

• Solid component

• Central blood flow on colour Doppler

• Abnormal free fluid

• Septation

Hyperechoic structures, no solid component

Brown DL, 1998 (n= 211)

Ultrasound scoring

Malignant ovarian tumours

Degenerated pedunculated fibroid

Usefulness and limitations of Doppler

waveform analysis

• Improves confidence in diagnosis1

• Overlap with inflammatory masses and corpus luteal cysts

• Overlap of indices between benign and malignant masses

• Intraobserver and interobserver variation

1. Valentin, 1999

Risk of malignancy

• Risk of malignancy index1-2

• Scoring systems3-5

• Logistic regression models6

1. Jacobs I 1990, 2. Tingulstad 1996

3. Brown DL 1998, 4. Lerner JP, 1994 5. Sassone AM 1991

6. Holsbeke CV 2007 (IOTA, External validation of mathematical models)

Ten simple rules (International Ovarian tumour analysis, IOTA)

"M" rules "B" rules

M1 Irregular solid tumour B1 Unilocular

M2 Presence of ascites B2 presence of solid components <7mm

M3 At least 4 papillary structures B3Presence of acoustic shadows

M4Irregular multilocular solid tumour, diameter >/= 100mm B4

Smooth multiloculartumour, <100 mm

M5 Very strong blood flow (score 4) B5 No blood flow (score 1)

1. Timmerman et al, UOG 2008 (n=1233 adnexal tumours), IOTA study2. Nunes N, et al, UOG 2014 (validation & meta-analysis), rules applied to 78% of tumours)

Applicable to 76% of tumours (sensitivity =93%, specificity = 90%, LR+: 9.45, LR-:0.08)

Limitations of 10 simple rules

• Rare benign tumours

• Stromal tumours

• Peritoneal inclusion cysts

• Tuboovarian complex (ovarian

abscesses)

• Hydrosalpinx

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CONCLUSION

• Benign ovarian masses outnumber malignant

• Overlap of sonographic appearances

• Efficacy and limitations of colour Doppler

• Use of MRI for problem-solving, workup of masses of uncertain origin, or possibly benign ovarian lesions

• CT for pre-operative staging