Ovarian chocolate cyst with markedly elevated serum CA19-9 level: a case report.

We report a patient with ovarian chocolate cyst with an abnormally high serum CA19-9 level (2380 U/ml) in whom MRI (Magnetic Resonance Imaging) was especially useful for the diagnosis. CA19-9 was detected in the epithelium of the chocolate cyst by the immunohistochemical technique, but it was not detected in the endometrium and adenomyotic tissue of the uterus. Twelve weeks were needed for normalization of the serum level of CA19-9 after operation.