Synopsis
Differentiate three common persistent benign ovarian masses, connect imaging phenotype with symptoms and fertility priorities, and plan appropriate specialist surveillance or tissue-preserving surgery while respecting diagnostic uncertainty.
- A mature cystic teratoma, commonly called a dermoid, contains tissues from more than one germ layer; fat, hair, calcification and an echogenic mural nodule create its characteristic but not infallible imaging pattern.
- An endometrioma forms from ectopic endometrial tissue within the ovary and often shows homogeneous low-level ground-glass echoes; symptoms and specialist imaging assess associated deep endometriosis.
- Serous cystadenomas are often thin-walled and unilocular, whereas mucinous cystadenomas may become large and multilocular; neither label is definitive until histopathology.
- Persistence distinguishes these masses from most functional cysts. Compare serial morphology and growth, but do not let apparently benign imaging override new pain, cancer symptoms or acute deterioration.
- Refer suspected or confirmed endometrioma to a specialist endometriosis service under NICE guidance, particularly when pain, fertility or deep disease requires coordinated decisions.
- There is no evidence-based dermoid diameter that automatically mandates surgery; RCOG notes that studies of observation commonly used an arbitrary 50–60 mm upper limit.
- When endometrioma surgery is considered for fertility, discuss cystectomy versus drainage and ablation, spontaneous-pregnancy benefit, recurrence and potential loss of ovarian reserve.
- For presumed benign surgery, laparoscopy is usually preferred when feasible, with ovarian cystectomy where appropriate and planned specimen containment to limit spillage.
Key red flags
Acute unilateral pain with vomiting in a patient with a dermoid or other ovarian mass is torsion until urgent assessment makes that diagnosis unlikely.
Ascites, irregular vascular solid tissue, papillary projections, peritoneal nodules or unexplained weight loss requires gynaecological-oncology triage rather than benign cyst surgery.
A rapidly enlarging or very large multilocular lesion can cause pressure, compromise imaging completeness and occasionally conceal a borderline or malignant process.
Fever, marked tenderness and inflammatory illness with a complex mass may represent tubo-ovarian abscess, including infection superimposed on endometriosis.
Bilateral endometriomas, previous ovarian surgery or a solitary functioning ovary raises the consequence of further tissue loss and warrants early fertility-aware planning.
Investigation priorities
Describe origin, dimensions, locules, wall, contents, acoustic shadows, papillary structures, solid tissue and vascularity.
Management branches
Ultrasound suggests a mature cystic teratoma without acute symptoms or malignant features.
- Assess maximum diameter, growth, pain, reproductive priorities, ovarian reserve context and confidence that the entire lesion was visualised.
- Explain that no evidence-based operative cutoff exists and agree surveillance or surgery through informed preference rather than an automatic number.
- If operating, favour tissue-preserving laparoscopy when suitable, use containment and clear any inadvertent sebaceous spill with thorough warm lavage.