Table 2.

Differential diagnosis table for uterine fibroid with cystic degeneration.

Diagnosis	Etiology, Mechanism	Imaging
Ovarian malignancy	The exact etiology is unknown. The strongest risk factor is a family or personal history of ovarian and/or breast cancer. Other studies have suggested environmental factors also play a role.	Plain radiograph, US, CT: The presence of ascites is more often found in malignant tumors, but this is not always the case. CT: The presence of an ovarian vascular pedicle sign is a way to confirm a mass of ovarian origin.
Uterine fibroid with cystic degeneration	Progressive enlargement of a fibroid eventually outgrows its own blood supply, leaving its core avascular. Thus, causing degeneration.	US: - Minimal echogenicity and irregular anechoic areas with a possible high echogenicity cluster accompanied by distal acoustic shadowing. MRI: - The stalk of the pedunculated fibroid can be identified. - Identifiable normal ovaries - Identifiable attachment of the mass to the round ligament. - Presence of bridging vascular sign.
Endometrioma	This is caused by the bleeding of an ectopic, hormonally active endometrial tissue located in the ovary following the menstrual cycle.	US: - The most common finding is a single locule cyst with diffuse ground-glass echoes and acoustic enhancement. - The presence of multiple locules is less common. - A hyperechoic wall can be found but is less common. - Rare forms include a partly solid or purely solid mass. MRI: - T1: hyperintense lesions without signal loss in T1 fat-suppressed sequence. - T2: Hypointense lesion with a possible T2 dark spot sign as a sign of chronic hemorrhage.