4.7 Ovary

Question 1

Ovarian location, volumes

Answer 1

Intraperitoneal, internal iliac artery and ureter lie posterior, external iliac vein anterosuperiorly
Ovarian artery from aorta just below renal arteries; left ovarian vein to left renal vein, right ovarian vein to IVC
Volumes - 3 mL pre-menarche, 10 mL menstruating, 6 mL postmenopausal
Abnormal if >18 mL premenopausal or >8 mL postmenopausal

Question 2

Ovarian Ligaments

Answer 2

Mesovarium - ovary to posterior surface broad ligament
Ovarian ligament - ovary to uterus
Suspensory ligament - ovary to pelvic side wall

Question 3

Ovarian tumours - benign and malignant features

Answer 3

Benign features: Less than 4 cm diameter and 3 mm wall thickness, entirely cystic with no internal structure
Malignant features: Thick wall and septa, papillary projections, internal soft tissue ± necrosis; invasion / implants / ascites / LNs
Size: less than 5 cm = 1% malignant, 5-10 cm = 6% malignant, >10 cm = 40% malignant

Question 4

Ovarian cyst classification

Answer 4

Physiological (less than 25 mm diameter): Follicles, Corpus luteum
Functional (can cause haemorrhage / rupture / torsion): Follicular cyst, Corpus luteum cyst, Theca lutein cysts
Others: Paraovarian cysts, Peritoneal inclusion cysts

Question 5

Features of functional ovarian cysts

Answer 5

Follicular cyst (>25 mm, produce oestrogen, ±internal echoes; repeat US at 2 or 6 weeks)
Corpus luteum cyst (can be 5-10 cm, produce progesterone, bleeding into / failed resorption of corpus luteum, maximum size at 8-10 weeks in pregnancy, resolve at 16 weeks)
Theca lutein cysts (GTD, usually bilateral and multilocular, may measure up to 20 cm)

Question 6

Paraovarian cysts - definition, frequency, diagnosis

Answer 6

Embryonic remnant in broad ligament; 10% of adnexal masses; must see ovary separately for diagnosis

Question 7

Peritoneal inclusion cysts - definition, imaging

Answer 7

Nonneoplastic reactive mesothelial proliferations; extraovarian location with ‘spiderweb’ pattern of entrapped ovary only in premenopausal with hx PID / surgery; can also simulate hydrosalpinx and paraovarian cysts

Question 8

Postmenopausal cysts

Answer 8

Require evaluation with TVUS; US follow-up if less than 5 cm

Question 9

PCOS CFs, imaging features

Answer 9

Stein-Leventhal triad: Oligomenorrhoea, hirsutism, obesity
Hormones: Elevated LH and LH/FSH ratio, elevated androgens
Bilateral enlarged ovaries (similar size bilaterally) with >5 peripherally located cysts, each >5 mm, with a hyperechoic stroma
Hypoechoic ovary without individual cysts (25%), Normal ovary (25%)

Question 10

Benign ovarian tumour types

Answer 10

Benign serous cystadenoma: Thin walled, uni- or multilocular, homogenous on CT and MR, no endo- or exocystic vegetations
Benign mucinous cystadenoma: Usually larger, almost always multilocular (varying density locules), smooth walls and septae

Question 11

Malignant ovarian tumours - associations, types, CA125 positivity

Answer 11

25% gynaecological malignancy, 65% metastatic at diagnosis; CA125 positive (>35) in 35% (early) - 80% (metastatic), but if less than 50 y/o then 85% of elevated CA125 due to benign disease, positive in serous > mucinous
Risks: Nulliparity, family history, high fat diet
1. Epithelial tumours (65%): Malignant serous or mucinous cystadenocarcinoma (25%); Endometroid carcinoma (10-15%); Clear cell carcinoma (5%); Brenner tumour (= transitional cell tumour)
2. Germ cell tumours (15-20%; elevated AFP and hCG if malignant): Mature teratoma (commonest and only benign germ cell tumour); Immature teratomas; Dysgerminomas; Endodermal sinus tumour; Others (embryonal carcinoma, choriocarcinoma, yolk sac tumour)
3. Sex-cord stromal tumours (8%): Granulosa cell; Fibrothecoma; Sclerosing stromal cell tumour; Sertoli and Leydig cell tumours (less than 0.5% ovarian neoplasms)
4. Metastatic (10%, usually young): Usually colorectal, stomach; Others: Breast, lung, contralateral ovary

Question 12

Epithelial ovarian tumours - types

Answer 12

Malignant serous or mucinous cystadenocarcinoma (25%): Serous 50% bilateral; Mucinous 25% bilateral
Endometroid carcinoma (10-15%): 30-50% bilateral; 15-30% association with endometrial cancer / hyperplasia
Clear cell carcinoma (5%): Nearly all have previous endometriosis, often presents as large endometrioma with solid components
Brenner tumour (= transitional cell tumour): Small, rarely malignant, 30% association with other ovarian tumours

Question 13

Brenner tumour imaging

Answer 13

AKA transitional cell tumour; Small, rarely malignant, 30% association with other ovarian tumours; Multilocular cystic mass or small mostly solid mass ± enhancement of solid components
MR: low signal, CT: extensive amorphous calcification

Question 14

Germ cell ovarian tumours

Answer 14

15-20% of all; elevated AFP and hCG if malignant
Mature teratoma (commonest and only benign germ cell tumour)
Immature teratomas
Dysgerminomas (5%)
Endodermal sinus tumour
Others: embryonal carcinoma, choriocarcinoma, yolk sac tumour (less than 20 y/o, raised AFP)

Question 15

Mature ovarian teratoma - imaging

Answer 15

Commonest and only benign germ cell tumour
Commonest benign ovarian tumour if less than 45 y/o, two or more embryonic germ cell layers (sebum, hair, bone, fat)
88% filled with sebaceous material (high T1W) and lined by squamous epithelium with echogenic material
Usually have Rokitansky nodule projecting into cavity
CT: fat ± mural calcification is diagnostic

Question 16

Struma ovarii definition, complication

Answer 16

Mature ovarian teratoma with predominantly thyroid tissue

Can cause torsion, rupture, malignant degeneration

Question 17

Immature teratomas - definition, imaging

Answer 17

Immature tissue from all 3 germ cell layers, less than 20 y/o, rapidly growing
Large cystic mass with cystic and solid components, scattered calcifications, ± capsular perforation

Question 18

Dysgerminomas - frequency and imaging

Answer 18

5% malignant ovarian tumours
Usually less than 30 y/o, ovarian counterpart of seminoma, often speckled calcification
Multilobulated, solid mass with fibrovascular septa ± necrosis, haemorrhage

Question 19

Endodermal sinus tumour - imaging, association

Answer 19

10-20 y/o, large complex solid/cystic pelvic mass, rapid growth and poor prognosis, may coexist with mature teratoma

Question 20

Sex-cord stromal tumours - frequency, origin, location

Answer 20

8% of malignant ovarian tumours; From granulosa, theca, Leydig, Sertoli cells and fibroblasts, mostly benign / confined to ovary at diagnosis
Granulosa cell
Fibrothecoma
Sclerosing stromal cell tumour
Sertoli and Leydig cell tumours (less than 0.5% ovarian neoplasms)

Question 21

Granulosa cell tumour - age, association, bilaterality

Answer 21

Commonest oestrogen producing and sex-cord stromal tumour; usually peri-/postmenopausal; associated with endometrial polyps, hyperplasia and carcinoma (3-25%), 95% bilateral

Question 22

Fibrothecoma - origin, age, CT/MR, association

Answer 22

Arise from stroma, postmenopausal
Homogenous hypoechoic mass, posterior acoustic shadowing, delayed homogenous enhancement on CT with dense calcifications, Low signal on T1W and very low on T2W with scattered high signal (oedema / cystic degeneration)
Commonest sex cord tumour (fibroma, 4%; thecoma 1%), Lipid rich with oestrogenic activity; association with ascites and Meigs syndrome (unilateral pleural effusion)

Question 23

Sclerosing stromal cell tumour - age, imaging

Answer 23

Benign, usually young women; large mass with solid and cystic components
Early peripheral enhancement with centripetal progression on dynamic studies

Question 24

Sertoli and Leydig cell ovarian tumours - frequency, age, CFs, imaging

Answer 24

Less than 0.5% ovarian neoplasms
Low grade malignancy, usually young women, almost always unilateral commonest virilising tumour, heterologous tissue
Well defined solid enhancing mass with intratumoral cysts

Question 25

Metastatic ovarian lesions - origin, age

Answer 25

10% of all ovarian tumours, occur during reproductive years
Commonest: Colorectal, stomach
Others: Breast, lung, contralateral ovary

Question 26

Kruckenberg tumour - origin, imaging

Answer 26

Mucin secreting signet ring cells, usually from GIT; shows bilateral complex masses with hypointense T1W solid components and internal high T2

Question 27

Staging ovarian cancer

Answer 27

I: Limited to ovary
II: Both ovaries ± ascites
III: Intraperitoneal metastases
IV: Extraperitoneal metastases

Question 28

Ovarian torsion - cause, imaging

Answer 28

Lead points often tumours / cysts, usually children / adolescents
US: Enlarged ovary, multiple follicles, free fluid ± absent flow (not diagnostic)

Question 29

Ovarian vein thrombosis - side, cause

Answer 29

Rare cause of PE, right > left

Usually due to infection, hypercoaguable state, postpartum (especially if post Caesarian Section)