The 3 images shown below reveal a different texture for different histologically confirmed endometriomas in different patients. Colour was used to enhance these differences. The first picture showed a fluid level occasionally seen in haemorrhagic cysts. Accordingly there is no appearance exclusively specific to an endometrioma and the clinical picture would help in the final interpretation of the result. This confirms the importance of pelvic scanning being conducted by gynaecologists who could use the scan probe to extend their clinical judgement for the benefit of that particular case. It could also be used to elicit site specific tenderness and to test for pelvic adhesions.
Normally pelvic organs move freely against each other and relative to the pelvic sidewall. This normal ‘sliding sign’ could not be elicited when organs are stuck together with adhesions. However transvaginal scan or even MRI examinations might show no abnormality. This is especially so when only pelvic sidewall implants are present without any significant ovarian involvement..
Occasionally, cystic masses may be seen in the pelvis. It may be difficult to decide whether such a cystic mass rises from one ovary or the other. In such cases clinicians may resort to MRI to verify the nature of such cystic masses. It is important to keep paraovarian cysts in mind when seeing such extra ovarian cysts. They can attain very large size, but usually have simple cyst characteristics.
The above two ultrasound and laparoscopic images show a right paraovarian cyst with a neighbouring right cystic ovary.The patient presented with recurrent episodes of subacute right side pelvic pain, mostly due to intermittent torsion episodes of this cyst. Her symptoms totally resolved once the cyst was removed laparoscopically.
Dermoid cysts or cystic teratomas are the most common benign cysts in young women. They contain all cell types in the body except gonadal tissue. They constitute up to 25% of all ovarian neoplasm and could be bilateral in 15-20% of cases. The risk of malignant transformation is 1-3%. They are often diagnosed incidentally during pelvic scan examinations but could present with pain or pressure symptoms. Occasionally they might produce different chemicals and hormones which could dictate their presentation mode. They could show different echo-patterns during transvaginal scanning which is a reflection of the different types of tissues they harbour. The inner layer might have single or multiple protuberances (Rokitansky) containing bone, teeth or hair which are strong reflectors of ultrasound causing distal shadowing. Highly differentiated monodermal teratomas could be seen. A good example is the epidermoid mass with an inner lining entirely composed of stratified squamous epithelial cells with no evidence of any hair, bone or a Rokitansky tubercle. Hyper-reflective keratin would be the imposing texture on transvaginal scan examination. However the most frequent finding is the presence of hair strands which gives a characteristic ultrasound pattern. All these characteristics could be summarised into the following patterns which could be suggestive of the diagnosis:
An echo-poor cystic structure with an echogenic mass inside
Echogenic particles within a low echogenicity fluid giving a mesh-like appearance
Fat-fluid interface within the cyst.
Dermoid cysts usually grow 1.8 mm in diameter every year in premenopausal women. An increase in size of >2.0 cm every year and a size of >6.0 cm are usually used to indicate surgery because of the known complications of malignancy changes and torsion in such circumstances. On the other hand benign dermoid cysts virtually do no increase in size at all in postmenopausal women.
|A semi solid mass seen in the right ovary which proved to be a dermoid cyst. The other ovary was polycystic and harboured a mature follicle||Histologically confirmed dermoid cyst showing characteristic echo pattern of hair strands|
A small dermoid cyst showing a distinct fat-fluid interface.
Abdominal scan showing a cyst with typical hair shadows at the centre and Rokitansky nodule at the top left
| || Dermoid cysts are frequently bilateral and may have |
different ultrasound patterns in the two ovaries in the
same patient, as seen in the neighbouring ultrasound
| The neighbouring image shows an epidermoid |
mass in the left ovary with echogenic but
homogeneous keratin texture. No Rokitansky
nodule, bone orhair shadows were seen. A
vascular corpus luteum is seen in the right ovary.
Other benign ovarian cysts
Mucinous cystadenomas make 20% of all benign ovarian tumours and tend to occur more often in middle age women. They could reach large size of 20 - 30 cm before being discovered. Small cysts with different echogenicity could be found along the thickened wall of the large cyst. They are all filled with mucous which has low echogenicity and could show layering with the more reflective layer at the back of the large cyst. As well papillary projections are occasionally found on the inner wall of the larger cyst. In most cysts blood vessels could be seen within the thickened wall making Doppler studies less diagnostic of malignant changes.
Serous cystadenomas make 30% of benign ovarian tumours and are usually much smaller than the mucinous ones. They could be bilateral in up to 30% of the cases. They are multilocular with clear fluid and multiple small papillae projecting into the cyst from the inner cyst wall. Doppler studies usually show no blood flow within the cyst wall but would be of high impedance if at all detectable. They are more liable to change malignant than the mucinous type to form serous adenocarcinoma which make about 70% of all ovarian carcinomas.
Solid ovarian masses
This group include fibromas which are the most common type, granulosa cell tumour and Brenner tumours. They all tend to have the same ultrasound appearance of uniform echotexture which is more echogenic compared to the neighbouring normal ovarian tissues. With granulosa cell tumour the endometrium would show excessive oestrogen stimulation and the patient would give history of recurrent episodes of uterine bleeding.
In young adolescent girls they are most probably germ cell tumours including dysgerminomas, immature teratomas and endometrial sinus tumour. Tumour markers including hCG, alpha fetoprotein and lactate dehydrogenase should be checked. In this young age group unilateral oophorectomy is the most likely line of management with adjuvant chemotherapy.
The first image below shows a solid mass in the right ovary seen as a dark shadow. This is also shown in the second coronal image of the same ovary. The third laparoscopy image showed a winkled hard mass rising form the outer surface of the right ovary. This proved to be spindle cell tumour after histopathological examination. This patient was 32 years old at the time.
Other solid adnexal masses should be kept in mind. The ultrasound image below shows a large solid heterogenous mass initially thought to be either an ovarian fibroma or broad ligament fibroid. 3D rendering revealed the mass to be attached to the right ovary, with no anatomical connection to the uterus. It proved to be a parasitic fibroid attached to the right ovary as seen in the image below. The mass was a coincidental finding in a patient who presented with long-standing secondary amenorrhoea. The mass was removed laparoscopically and the patient resumed menstruating within few weeks. This case was reported in Gynaecological Surgery as: 'Secondary amenorrhoea with high inhibin B level caused by parasitic
Before moving on from solid ovarian or adnexal masses, it is a right statement to make that all solid or partially solid ovarian masses should be treated surgically especially in postmenopausal women.
The life time risk of malignancy is 1.8% which is reduced to 0.8% after using an oral contraceptive pill for 5 years. On the other hand this risk is increased to 6.7% if a first degree relative has already been inflicted and to 40% in families with a genetic syndrome. Other factors including the patient’s age and the size of the cyst should be taken into consideration when making a provisional diagnosis of the nature of an adnexal mass. The life time risk of malignancy at the age of 60-69 years is 12 times more than at the age of 20-29 years. On the size side, masses > 10 cm in diameter are more likely to be malignant.
The ultrasonic characteristic usually seen with ovarian malignancy include:
On the other hand the presence of healthy ovarian tissue on the side of a cyst or a mass [crescent sign] is strongly suggestive of a benign nature. Absence of such a sign has a sensitivity of 96% and specificity of 76% in diagnosing ovarian carcinoma. However, it is not very helpful in differentiating benign from borderline masses.
The importance of these characteristics in differentiating benign from malignant cysts is especially important in 10-15% of postmenopausal women who still show ovarian cysts at different times. Purely cystic masses less than 5 cm in diameter with no septate or solid components are most unlikely to be malignant. With a normal CA 125 test the patient should be scanned after 3, 6. 9, 12 months and annually afterwards. Surgical intervention will be indicated if the patient became symptomatic, or the cyst changed texture or increased in size. On the other hand, a high CA 125 level in a postmenopausal woman with an ovarian mass has a positive predictive value of 70% for diagnosing a malignancy.
It is important to mention that the value of CA125 in the diagnosis of cancer is hampered by the fact that it is a marker of epithelial tumours. Furthermore, it can be increased in many non malignant conditions, including endometriosis and fibroids.
In recent years ultrasound scan examinations by experienced operators have been found to be reliable in the clinical diagnosis of ovarian cancer. In fact, few publications showed that including CA125 in the diagnostic setup reduced the diagnostic sensitivity of the ultrasound scan examination.
Presence of fluid in the pelvis is an important sign to look for especially in postmenopausal women. Normally little if any fluid may be seen in the pouch of Douglas in postmenopausal women, ranging between <2 ml - 5.5 ml, as reported by different authours. Accordingly, moderate amount of fluid should raise the suspicion of the attending gynaecologist to the possibility of ovarian malignancy, or hepatic disease.
The above two ultrasound images show respectively:
- A large left ovarian cyst with multiple septae seen in a 60 year old patient who presented with postmenopausal bleeding. The cyst proved to be malignant. The complex mass in the right ovary showed solid and cystic areas in the same patient. It also proved to be malignant.
- The second image in a different patient shows a highly echogenic solid area flanked by an area of medium echogenicity and two totally anechoic areas
Though different reliable scoring systems are used to differentiate malignant from benign ovarian cysts and masses, histological diagnosis remains to be the most reliable method.
- The first ultrasound image above shows a unilocular solid cyst, with ground glass fluid appearance, and two solid areas inside. The cyst wall was 1.6 cm thick.
- The second colour Doppler ultrasound image shows axial and sagittal views of the same cyst respectively, with predominantly peripheral vascular channels, without the bizarre pattern commonly seen in malignant tumours.
This mass proved to be an endometrioid carcinoma of the left ovary. The patient was 38 years old, had vague abnominal pains, excessive but regular menstrual loss, no change in body weight and no evidence of ascites.
The neighbouring ultrasound image shows a multicystic solid ovarian mass. There is only one solid area in the cyst, with a second small attached cystic area. There are no septae, and power Doppler mapping showed poor peripheral vascularisation. Histopathological assessment showed a borderline ovarian tumour.
Role of Doppler Ultrasound
Doppler studies did not fulfil the great expectations raised initially in helping with the diagnosis of ovarian malignancy. The initial plethora of articles documenting particular cut off figures of PI and RI has been replaced by non-numerical criteria for that purpose. With ovarian malignancy penetrating vessels with bizzare arrangements into the mass, along the septae or into papillary excrescences is more suggestive of malignancy than peripheral arrangement of blood vessels around the cyst, which is mostly seen with benign tumours. The image below demonstrate the rich penetrating pattern in an ovarian mass proved to be malignant.
Pelvic masses of non-ovarian origin should always be kept in mind. Examples of such lesions include broad ligament fibroids, pedunculated uterine fibroids, tubo-ovarian inflammatory lesions and diverticular abscesses.