Mature cystic teratoma (dermoid cyst)

Definition

• Mature cystic teratoma (dermoid cyst) is a benign germ cell tumour composed of tissues from all three germ layers; ectodermal tissue and sebaceous material are present in almost every case.

Classification

• Besides the mature cystic teratoma as the commonest form, there are monodermal teratomas such as struma ovarii and carcinoid tumours, and fetiform teratomas.

Occurrence & epidemiology

Epidemiology

• It is the most common ovarian germ cell tumour in young women; teratomas account for about 20% of all ovarian neoplasms.
• Patients are younger than those with epithelial tumours, with a mean age of about 30 years; bilateral involvement is reported in 8–15%, and growth is about 1.8 mm per year.

Clinical features

Clinical features and complications

• The tumour is often detected incidentally on imaging or pelvic examination; chronic pelvic pain or a palpable mass may occur, and acute pain indicates a complication.
• Complications are torsion (16%), rupture (1–4%) with possible chemical peritonitis, malignant transformation (0.5–3%), infection and, rarely, autoimmune haemolytic anaemia or anti-NMDA receptor encephalitis; malignant change mainly affects older women.

Histology

• The cyst wall bears squamous epithelium; the cavity is filled with sebaceous material that is liquid at body temperature.

Diagnosis

Typical imaging findings

• Ultrasound: An adnexal mass of mixed echogenicity is seen. A strongly echogenic, rounded nodule stands out from the rest of the contents and casts an acoustic shadow; beside it are fine echogenic lines and dots floating within the cyst.
• Ultrasound: A round, predominantly hyperechoic mass with a heterogeneous internal structure on the ovary — consistent with a mature cystic teratoma (dermoid cyst) containing fatty components.

• On ultrasound, the dermoid plug (Rokitansky nodule), the dot-dash pattern from hair, the tip of the iceberg sign and fat-fluid levels are typical.
• On CT and MRI the detection of fat is diagnostic; on MRI the fatty layer is T1-hyperintense and loses signal on fat-suppressed sequences.

Keep learning in the app

Further reading (selection)

1. Mature Cystic Teratoma: An Integrated Review (Int J Mol Sci 2023, PubMed Central)
2. Mature cystic teratoma of the ovary: a cutting edge overview on imaging features (Insights Imaging 2017, PubMed Central)

Cross-references