Endometrioma
Updates to Article Attributes
Endometriomas,also known as a chocolate cysts or endeometriotic cysts, are a localised form of endometriosis and are usually within the ovary. They are readily diagnosed on ultrasound, with most demonstrating classical radiographic features.
Epidemiology
It affects women of reproductive age.
Pathology
Endometriomas contains dark degenerated blood products following repeated cyclical haemorrhage. The cysts may be up to 20 cm in size although they are usually smaller (2-5 cm).
Location
Typical locations include:
- ovaries: ~75%
- anterior/posterior cul-de-sac: ~70%
- posterior broad ligament: ~50%
- uterosacral ligaments: ~35%
- uterus: ~10 %
- colon: ~5%
Radiographic features
Plain film
Not usually helpful in diagnosis; ~10% of endometriomas can calcify.
Ultrasound
The appearances of endometriomas can be quite variable.
The classical example is of an unilocular cyst with acoustic enhancement with diffuse homogeneous ground-glass echoes as a result of the haemorrhagic debris. This appearance occurs in 50% of cases 7.
Less typical features include 7:
- multiple locules (~85% will have <5 locules)
- hyperechoic wall foci (present in 35%)
- cystic-solid lesion (~15%) or purely solid lesion (1%)
- anechoic cysts (rare; 2%)
MRI
Signal characteristics vary according to the age of any complicating haemorrhage 6:
-
T1:
- typically, lesions appear hyperintense while acute haemorrhage occasionally appears hypointense
- endometriomas with high T1 signal characteristically do not show loss of signal on T1 fat suppressed sequence, which is important to differentiate from mature cystic teratoma of the ovary
-
T2
- typically hypointense owing to the presence of deoxyhaemoglobin and methaemoglobin (shading sign), which is very suggestive of endometrioma 3
- T2 dark spot sign is specific for chronic haemorrhage and is helpful in diagnosing endometriomas 9.
- old haemorrhage occasionally appears hyperintense
Treatment and prognosis
Although endometriomas are usually a benign entity, there is an ~1% rate of malignant transformation. Endometrioid tumors of the ovary and clear cell adenocarcinoma are the most common histological pattern seen 8. They are mostly seen in women >40 years after several years of latency, with endometriomas larger than 9 cm 4-5. Malignant transformation is uncommon in masses <6 cm.
If not surgically excised, follow-up should be at least yearly 4. GnRH agonists may be used for medical management.
Differential diagnosis
General imaging differential considerations include:
- haemorrhagic ovarian cyst
- ovarian dermoid cyst: will show fat suppression on fat suppressed sequences on MRI
- cystic neoplasm
- tubo-ovarian abscess
-<li>hyperechoic wall foci</li>- +<li>hyperechoic wall foci (present in 35%)</li>
-<a title="T2 dark spot sign" href="/articles/t2-dark-spot-sign">T2 dark spot sign</a> is specific for chronic haemorrhage and is helpful in diagnosing endometriomas <sup>9</sup>. </li>- +<a href="/articles/t2-dark-spot-sign">T2 dark spot sign</a> is specific for chronic haemorrhage and is helpful in diagnosing endometriomas <sup>9</sup>. </li>
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