Presentation
10/40 pregnant. Acute lower abdominal pain. Irregular right adnexal mass seen on ultrasound, appendix not identified.
Patient Data
Large heterogeneous mass arising from right ovary, with normal left ovary. The mass contains a large quantity of fat, as noted by the suppression of signal between the T1 and T1FS images. There are also areas of dense calcification and a solid frond-like mass in the left posterior portion. The appearances are in keeping with a large dermoid cyst. There is no free fluid in the pelvis, and no edema around the mass.
Elsewhere, the uterus contains a gestation sac. The appendix is seen as a high signal structure on the diffusion-weighted imaging but is not distended or surrounded by edema on the other images, so this is not considered to be acute appendicitis.
The patient's symptoms settled so she was managed conservatively and the lesion resected at term at C-section.
Histopathology
Clinical History: Dermoid cyst. Removed at cesarean section.
Macroscopic: Edematous Fallopian tube measuring 40 x 10mm with attached ovary/cyst measuring 110 x 90 x 75mm. On slicing, the cyst contains keratinous yellow material with hair. Small areas of orange brownish material ?hemorrhage. Some bony areas are also noted and a brown cystic area is identified measuring 15 x 8 x 9mm. The cyst appears biloculated.
Microscopic: The cyst shows areas of infarction. It is partly lined by keratinizing squamous epithelium with underlying pilosebaceous units associated with a giant cell reaction most likely representing an inflammatory reaction to keratinous material. The wall consists of adipose tissue and some fibroconnective tissue with ovarian stroma. The appearances would be in keeping with a mature cystic teratoma (benign dermoid cyst) with areas of infarction. There are no immature elements and there is no evidence of malignant somatic transformation. The fallopian tube appears edematous but otherwise shows no specific abnormality.
Conclusion: Right ovarian cyst - mature cystic teratoma (benign dermoid cyst). Right Fallopian tube - edema.
Case Discussion
The MRI appearances are typical for an ovarian mass containing different tissue types including fat, calcification, and soft tissue, and therefore typical for an ovarian dermoid cyst. There were no clinical or imaging signs of ovarian torsion, and due to clinical stability, the patient was managed conservatively through to term and the mass was resected at C-section and confirmed at pathology analysis to be a dermoid cyst (mature cystic teratoma).