Endometrioma
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View Jeremy Jones's current disclosuresAt the time the article was last revised Tariq Walizai had no financial relationships to ineligible companies to disclose.
View Tariq Walizai's current disclosures- Chocolate cyst
- Chocolate cysts
- Endometriotic cyst
- Endometriotic cysts
- Endometriomas
- Endometrioma
Endometriomas, also known as chocolate cysts or endometriotic cysts, are a localized form of endometriosis and are usually within the ovary. They are readily diagnosed on ultrasound, with most demonstrating classical radiographic features.
On this page:
Epidemiology
These occur in up to 10% of women of reproductive age.
Clinical presentation
The symptoms do not necessarily correlate with disease severity and include pelvic pain, dysmenorrhea, dyspareunia and infertility in 30-40% of patients.
Pathology
Although the pathogenesis is still under discussion, three theories have emerged:
metaplastic transformation of the peritoneal epithelium into functional endometrium
peritoneal seeding due to retrograde menstruation
activation of mesenchymal cells differentiation caused by endometrium in the peritoneal cavity from retrograde flow
Endometriomas contain dark degenerated blood products following repeated cyclical hemorrhage. 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%
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Radiographic features
Plain radiograph
Not usually helpful in diagnosis. ~10% of endometriomas can calcify.
Ultrasound
The appearances of endometriomas can be quite variable. The classical example is an avascular unilocular cyst containing low-level, homogeneous "ground-glass" like internal echoes, as a result of the hemorrhagic 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%) due to cholesterol deposits
cystic-solid lesion (~15%) or purely solid lesion (1%)
anechoic cysts (rare: 2%)
fluid-fluid level 10
CT
CT is not the preferred imaging modality to assess endometriosis, as image findings tend to be non-specific, nevertheless often patients will undergo CT for acute abdominal pain.
Endometriomas on CT tend to be complex pelvic cystic masses often with increased attenuation components representing hemorrhage. These appearances are non-specific also being seen with hemorrhagic ovarian cysts or neoplasms. Bilateral lesions points towards endometriomas but again maybe seen with other entities, such as a tubo-ovarian abscess or neoplasm 10.
MRI
Signal characteristics vary according to the age of any complicating hemorrhage 6:
-
T1
typically, lesions appear hyperintense while acute hemorrhage occasionally appears hypointense
endometriomas with high T1 signal characteristically do not show loss of signal on T1 fat-suppressed sequences, which is important for differentiating it from a mature cystic teratoma of the ovary
-
T2
typically hypointense owing to the presence of deoxyhemoglobin and methemoglobin (shading sign), which is very suggestive of an endometrioma 3
T2 dark spot sign is specific for chronic hemorrhage and is helpful in diagnosing endometriomas 9
old hemorrhage occasionally appears hyperintense
-
DWI/ADC
variable restricted diffusion
-
T1 C+ (Gd)
may have wall enhancement
the presence of an enhancing mural nodule is suggestive of malignant transformation
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Treatment and prognosis
Although endometriomas are usually benign entities, there is an ~1% rate of malignant transformation. Endometrioid tumors of the ovary and clear cell ovarian carcinomas are the most common histological patterns 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.
Endometriomas have the potential to decidualise during pregnancy resulting in the formation of vascularized, papillary projections13 (solid internal components with flow on color doppler). Although rare, these changes give an appearance mimicking malignancy and careful follow-up imaging is recommended.
Ovarian endometriomas carry a lower risk of ovarian torsion than other ovarian cysts due to their frequent association with adhesions 14.
Differential diagnosis
General imaging differential considerations include:
-
brighter on T2-weighted images
absence of the "shading sign"
-
will show fat suppression on MRI fat-suppressed sequences
Quiz questions
References
- 1. Lee S. Radiological Reasoning: Imaging Characterization of Bilateral Adnexal Masses. AJR Am J Roentgenol. 2006;187(3 Suppl):S460-6. doi:10.2214/AJR.05.2226 - Pubmed
- 2. Lee S. Imaging Evaluation of Adnexal Masses: Self-Assessment Module. AJR Am J Roentgenol. 2006;187(3_supplement):S457-9. doi:10.2214/ajr.06.0785
- 3. Glastonbury C. The Shading Sign. Radiology. 2002;224(1):199-201. doi:10.1148/radiol.2241010361 - Pubmed
- 4. Levine D, Brown D, Andreotti R et al. Management of Asymptomatic Ovarian and Other Adnexal Cysts Imaged at US: Society of Radiologists in Ultrasound Consensus Conference Statement. Radiology. 2010;256(3):943-54. doi:10.1148/radiol.10100213 - Pubmed
- 5. Kobayashi H. Ovarian Cancer in Endometriosis: Epidemiology, Natural History, and Clinical Diagnosis. Int J Clin Oncol. 2009;14(5):378-82. doi:10.1007/s10147-009-0931-2 - Pubmed
- 6. Umaria N & Olliff J. Imaging Features of Pelvic Endometriosis. Br J Radiol. 2001;74(882):556-62. doi:10.1259/bjr.74.882.740556 - Pubmed
- 7. Van Holsbeke C, Van Calster B, Guerriero S et al. Endometriomas: Their Ultrasound Characteristics. Ultrasound Obstet Gynecol. 2010;35(6):730-40. doi:10.1002/uog.7668 - Pubmed
- 8. Takeuchi M, Matsuzaki K, Uehara H, Nishitani H. Malignant Transformation of Pelvic Endometriosis: MR Imaging Findings and Pathologic Correlation. Radiographics. 2006;26(2):407-17. doi:10.1148/rg.262055041 - Pubmed
- 9. Corwin M, Gerscovich E, Lamba R, Wilson M, McGahan J. Differentiation of Ovarian Endometriomas from Hemorrhagic Cysts at MR Imaging: Utility of the T2 Dark Spot Sign. Radiology. 2014;271(1):126-32. doi:10.1148/radiol.13131394 - Pubmed
- 10. Bennett G, Slywotzky C, Cantera M, Hecht E. Unusual Manifestations and Complications of Endometriosis—Spectrum of Imaging Findings:Pictorial Review. AJR Am J Roentgenol. 2010;194(6_supplement):WS34-46. doi:10.2214/ajr.07.7142 - Pubmed
- 11. Woodward P, Sohaey R, Mezzetti T. Endometriosis: Radiologic-Pathologic Correlation. Radiographics. 2001;21(1):193-216. doi:10.1148/radiographics.21.1.g01ja14193 - Pubmed
- 12. Patel M, Feldstein V, Chen D, Lipson S, Filly R. Endometriomas: Diagnostic Performance of US. Radiology. 1999;210(3):739-45. doi:10.1148/radiology.210.3.r99fe61739 - Pubmed
- 13. Mascilini F, Moruzzi C, Giansiracusa C et al. Imaging in Gynecological Disease (10): Clinical and Ultrasound Characteristics of Decidualized Endometriomas Surgically Removed During Pregnancy. Ultrasound Obstet Gynecol. 2014;44(3):354-60. doi:10.1002/uog.13323 - Pubmed
- 14. Dafna L, Ganer Herman H, Ginath S et al. Comparison of Emergent and Elective Surgeries of Endometriomas: Is Adnexal Torsion a Concern? Isr Med Assoc J. 2019;21(4):251-4. - Pubmed
Incoming Links
- IOTA ultrasound rules for ovarian masses
- Ovarian-Adnexal Reporting and Data System Ultrasound (O-RADS US)
- Deep endometriosis (transvaginal ultrasound)
- Broad ligament
- Endometrioid carcinoma of the ovary
- Chocolate cyst (disambiguation)
- Herlyn-Werner-Wunderlich syndrome
- Ovarian mucinous tumours
- Vegetable and plant inspired signs
- Endometriosis
- Complex adnexal mass - differential diagnosis (mnemonic)
- Shading sign (endometrioma)
- Ovarian serous cystadenoma
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- Gynaecologic Imaging-Reporting and Data System (GI-RADS)
- Haemorrhagic corpus luteal cyst
- T2 dark spot sign (endometrioma)
- Ovarian lesions with T2 hypointensity
- Hemorrhagic ovarian cyst
- Abdominal wall endometrioma
- Ovarian endometrioma with deep infiltration
- Endometriomas and peritoneal inclusion cysts
- Ovarian endometrioma - T2 dark spot sign
- Endometrioma showing diffusion restriction
- Endometrioma
- Endometrioma - shading sign
- Endometrioma
- Endometriotic cyst with T2 dark spot
- Abdominal wall endometriosis
- Endometrioma - T2 shading sign
- Adenomyosis and endometriotic cysts
- Focal adenomyosis with ovarian endometriomas
- Chocolate cyst (endometrioma) and focal uterine adenomyosis
- Endometrioma
- Ovarian endometrioma
- Diffuse uterine adenomyosis with ovarian endometrioma and deep infiltration
- Endometrioma
- Ovarian endometriomas - bilateral
- Ovarian endometrioma - T2 shading sign
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