Hyperechoic Rokitansky nodule with shadowing, dot-dash hair, and a fat-fluid level — transvaginal, after proving the mass is ovarian.
Orient first
- The Rokitansky nodule is a hyperechoic plug with acoustic shadowing. Dot-dash (dermoid mesh) lines are hair. A fat-fluid level is sebum floating on fluid.
- The ovarian CRESCENT — a rim of ovarian tissue at the edge — establishes origin. Without origin, contents do not make a dermoid.
- Colour Doppler should show no flow in sebum or hair; flow in a solid nodule is not a dermoid plug.
Acquire the study
- Transabdominal overview then transvaginal for the nodule and the ipsilateral ovary.
- Low-flow colour Doppler before calling any component solid.
The manoeuvre
- Identify both ovaries and state whether the mass arises from one of them.
- Look for a hyperechoic Rokitansky nodule with posterior shadowing.
- Look for dot-dash lines and a fat-fluid level.
- Apply colour Doppler: sebum and hair are avascular; a vascular solid nodule is not a dermoid plug.
What confirms it
- Ovarian origin PLUS macroscopic fat (Rokitansky nodule with acoustic shadowing, a fat-fluid level, or T1-bright content that suppresses on fat saturation) characterises a dermoid.
What licenses you to exclude it
- Absence of visible fat does not exclude a dermoid — a fat-poor teratoma exists. If origin is ovarian and the mass is complex, it still needs a lexicon category, not a forced dermoid call.
- This study does not exclude malignancy inside a dermoid (a rare collision or malignant transformation). Growing solid tissue, invasion or peritoneal disease reopens the question.
The classic misread
- Calling a hyperechoic nodule a dermoid without seeing the ovary of origin.
- Mistaking a haemorrhagic clot for a Rokitansky nodule — clot is avascular but does not shadow like sebum and hair.