Patient's question:
What causes chocolate cysts?Doctor's answer:
(1) Simple ovarian cyst: Follicular cysts or corpus luteum cysts are more commonly unilateral. The cyst wall is thin and distinct, with no adhesions around the cyst. The cyst varies in size and shape with the menstrual cycle. Chocolate cysts of the ovary are more commonly bilateral, with a thicker and less distinct cyst wall. On T2WI, the internal part may show extremely low signal shadow signs, with a low signal ring around it. Due to repeated bleeding within the cyst, it often adheres to surrounding tissues and organs, and clinical history of dysmenorrhea is common.(2) Ovarian cystadenoma: Ovarian cystadenomas are more commonly unilateral, with clear cyst wall margins. Clinically, they often show no symptoms. However, when the cystadenoma ruptures, adhesions may also occur around it. It is necessary to combine clinical history (such as history of dysmenorrhea, episodes of acute rupture, etc.) for differentiation.
(3) Pelvic abscess: On enhanced scans, the wall of a pelvic abscess shows ring-like enhancement, with a relatively thick enhancement ring. Clinically, there are often signs of inflammation.
(4) Ovarian cancer: When a chocolate cyst of the ovary has fresh bleeding, it may resemble a solid-cystic mass and needs to be differentiated from ovarian cancer. After enhanced scanning, the solid part of ovarian cancer shows significant enhancement or wall nodules, while the hemorrhagic part of chocolate cysts appears similar to a solid mass. On enhanced scans, there is no enhancement or wall nodules.
(5) Ovarian cystic teratoma: Cystic teratomas show uniform high signals on T1WI and T2WI, with chemical shift changes. On fat-suppression sequences, they appear as low signals, which is the best method for differentiation. Cystic teratomas often accompany calcification and generally show no adhesions to surrounding tissues.