Endometrioma

Changed by Henry Knipe, 12 Nov 2021

Updates to Article Attributes

Body was changed:

Show markup changes

Endometriomas,also known as chocolate cysts or endometriotic 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

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, dysmenorrhoea, dyspareunia and infertility in 30-40% of patients.

Pathology

Although the pathogenesis is still under discussion, three theories have emerged: ~~(1) metaplastic~~

Metaplastic transformation of the peritoneal epithelium into functional endometrium~~; (2) peritoneal~~.
Peritoneal seeding due to retrograde menstruation~~; (3) activation~~.
Activation of mesenchymal cells differentiation caused by endometrium in the peritoneal cavity from retrograde flow.

Endometriomas contain 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%

~~Clinical findings~~

~~The symptoms do not necessarily correlate with disease severity and include pelvic pain, dysmenorrhoea, dyspareunia and infertility in 30-40% of patients.~~

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 a 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 for differentiating it 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
DWI
- variable restricted diffusion
T1C+
- may have wall enhancement
- the presence of an enhancing mural nodule is suggestive of malignant transformation

Treatment and prognosis

Although endometriomas are usually a benign entity, there is an ~1% rate of malignant transformation. Endometrioid tumours 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
- brighter on T2-weighted images
- an absence of the "shading sign"
ovarian dermoid cyst
- will show fat suppression on fat ~~suppressed~~-suppressed sequences on MRI
cystic neoplasm
tubo-ovarian abscess

-<p><strong>Endometriomas</strong>,<strong> </strong>also known as <strong>chocolate cysts</strong> or <strong>endometriotic cysts</strong>, are a localised form of <a href="/articles/endometriosis">endometriosis</a> and are usually within the <a href="/articles/ovary">ovary</a>. They are readily diagnosed on ultrasound, with most demonstrating classical radiographic features. </p><h4>Epidemiology</h4><p>These occur in up to 10% of women of reproductive age.</p><h4>Pathology</h4><p>Although the pathogenesis is still under discussion, three theories have emerged: (1) metaplastic transformation of the peritoneal epithelium into functional endometrium; (2) peritoneal seeding due to retrograde menstruation; (3) activation of mesenchymal cells differentiation caused by endometrium in the peritoneal cavity from retrograde flow</p><p>Endometriomas contain 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).</p><h5>Location</h5><p>Typical locations include:</p><ul>
+<p><strong>Endometriomas</strong>,<strong> </strong>also known as <strong>chocolate cysts</strong> or <strong>endometriotic cysts</strong>, are a localised form of <a href="/articles/endometriosis">endometriosis</a> and are usually within the <a href="/articles/ovary">ovary</a>. They are readily diagnosed on ultrasound, with most demonstrating classical radiographic features. </p><h4>Epidemiology</h4><p>These occur in up to 10% of women of reproductive age.</p><h4>Clinical presentation</h4><p>The symptoms do not necessarily correlate with disease severity and include pelvic pain, dysmenorrhoea, dyspareunia and <a title="Female infertility" href="/articles/female-infertility">infertility</a> in 30-40% of patients.</p><h4>Pathology</h4><p>Although the pathogenesis is still under discussion, three theories have emerged:</p><ol>
+<li>Metaplastic transformation of the peritoneal epithelium into functional endometrium.</li>
+<li>Peritoneal seeding due to retrograde menstruation.</li>
+<li>Activation of mesenchymal cells differentiation caused by endometrium in the peritoneal cavity from retrograde flow.</li>
+</ol><p>Endometriomas contain 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).</p><h5>Location</h5><p>Typical locations include:</p><ul>
-</ul><h4>Clinical findings</h4><p>The symptoms do not necessarily correlate with disease severity and include pelvic pain, dysmenorrhoea, dyspareunia and infertility in 30-40% of patients.</p><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Not usually helpful in diagnosis; ~10% of endometriomas can calcify.</p><h5>Ultrasound</h5><p>The appearances of endometriomas can be quite variable. The classical example is a 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 <sup>7</sup>.</p><p>Less typical features include <sup>7</sup>:</p><ul>
+</ul><h4>Radiographic features</h4><h5>Plain radiograph</h5><p>Not usually helpful in diagnosis; ~10% of endometriomas can calcify.</p><h5>Ultrasound</h5><p>The appearances of endometriomas can be quite variable. The classical example is a 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 <sup>7</sup>.</p><p>Less typical features include <sup>7</sup>:</p><ul>
~~-<a href="/articles/mature-cystic-ovarian-teratoma-1">ovarian dermoid cyst</a><ul><li>will show fat suppression on fat suppressed sequences on MRI</li></ul>~~
+<a href="/articles/mature-cystic-ovarian-teratoma-1">ovarian dermoid cyst</a><ul><li>will show fat suppression on fat-suppressed sequences on MRI</li></ul>

References changed:

1. Lee S. Radiological Reasoning: Imaging Characterization of Bilateral Adnexal Masses. AJR Am J Roentgenol. 2006;187(3 Suppl):S460-6. <a href="https://doi.org/10.2214/AJR.05.2226">doi:10.2214/AJR.05.2226</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/16928898">Pubmed</a>
2. Lee S. Imaging Evaluation of Adnexal Masses: Self-Assessment Module. AJR Am J Roentgenol. 2006;187(3_supplement):S457-9. <a href="https://doi.org/10.2214/ajr.06.0785">doi:10.2214/ajr.06.0785</a>
3. Glastonbury C. The Shading Sign. Radiology. 2002;224(1):199-201. <a href="https://doi.org/10.1148/radiol.2241010361">doi:10.1148/radiol.2241010361</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/12091683">Pubmed</a>
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. <a href="https://doi.org/10.1148/radiol.10100213">doi:10.1148/radiol.10100213</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/20505067">Pubmed</a>
5. Kobayashi H. Ovarian Cancer in Endometriosis: Epidemiology, Natural History, and Clinical Diagnosis. Int J Clin Oncol. 2009;14(5):378-82. <a href="https://doi.org/10.1007/s10147-009-0931-2">doi:10.1007/s10147-009-0931-2</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/19856043">Pubmed</a>
6. Umaria N & Olliff J. Imaging Features of Pelvic Endometriosis. Br J Radiol. 2001;74(882):556-62. <a href="https://doi.org/10.1259/bjr.74.882.740556">doi:10.1259/bjr.74.882.740556</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/11459736">Pubmed</a>
7. Van Holsbeke C, Van Calster B, Guerriero S et al. Endometriomas: Their Ultrasound Characteristics. Ultrasound Obstet Gynecol. 2010;35(6):730-40. <a href="https://doi.org/10.1002/uog.7668">doi:10.1002/uog.7668</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/20503240">Pubmed</a>
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. <a href="https://doi.org/10.1148/rg.262055041">doi:10.1148/rg.262055041</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/16549606">Pubmed</a>
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. <a href="https://doi.org/10.1148/radiol.13131394">doi:10.1148/radiol.13131394</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/24475842">Pubmed</a>
1. Lee SI. Radiological reasoning: imaging characterization of bilateral adnexal masses. AJR Am J Roentgenol. 2006;187 (3): S460-6. <a href="http://dx.doi.org/10.2214/AJR.05.2226">doi:10.2214/AJR.05.2226</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/16928898">Pubmed citation</a><div class="ref_v2"></div>
2. Lee, Susanna I. Imaging Evaluation of Adnexal Masses: Self-Assessment Module American Journal of Roentgenology. 187 (3_Supplement): S457. <a href="http://dx.doi.org/10.2214/AJR.06.0785">doi:10.2214/AJR.06.0785</a> -<div class="ref_v2"></div>
3. Glastonbury CM. The shading sign. Radiology. 2002;224 (1): 199-201. <a href="http://radiology.rsna.org/content/224/1/199.full">Radiology (full text)</a> - <a href="http://dx.doi.org/10.1148/radiol.2241010361">doi:10.1148/radiol.2241010361</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/12091683">Pubmed citation</a><span class="ref_v3"></span>
4. Levine D, Brown DL, Andreotti RF 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. <a href="http://dx.doi.org/10.1148/radiol.10100213">doi:10.1148/radiol.10100213</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/20505067">Pubmed citation</a><div class="ref_v2"></div>
5. Kobayashi H. Ovarian cancer in endometriosis: epidemiology, natural history, and clinical diagnosis. Int. J. Clin. Oncol. 2009;14 (5): 378-82. <a href="http://dx.doi.org/10.1007/s10147-009-0931-2">doi:10.1007/s10147-009-0931-2</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/19856043">Pubmed citation</a><div class="ref_v2"></div>
6. Umaria N, Olliff JF. Imaging features of pelvic endometriosis. Br J Radiol. 2001;74 (882): 556-62. <a href="http://bjr.birjournals.org/cgi/content/full/74/882/556">Br J Radiol (full text)</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/11459736">Pubmed citation</a><div class="ref_v2"></div>
7. Van Holsbeke C, Van Calster B, Guerriero S et-al. Endometriomas: their ultrasound characteristics. Ultrasound Obstet Gynecol. 2010;35 (6): 730-40. <a href="http://dx.doi.org/10.1002/uog.7668">doi:10.1002/uog.7668</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/20503240">Pubmed citation</a><span class="auto"></span>
8. Takeuchi M, Matsuzaki K, Uehara H et-al. Malignant transformation of pelvic endometriosis: MR imaging findings and pathologic correlation. Radiographics. 2006;26 (2): 407-17. <a href="http://dx.doi.org/10.1148/rg.262055041">doi:10.1148/rg.262055041</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/16549606">Pubmed citation</a><span class="auto"></span>
9. Corwin MT, Gerscovich EO, Lamba R et-al. Differentiation of ovarian endometriomas from hemorrhagic cysts at MR imaging: utility of the T2 dark spot sign. Radiology. 2014;271 (1): 126-32. <a href="http://dx.doi.org/10.1148/radiol.13131394">doi:10.1148/radiol.13131394</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/24475842">Pubmed citation</a><span class="auto"></span>