Presentation
Abdominal pain, nausea and vomiting.
Patient Data
Cystic mass within the pelvis arising from the right adnexa with a fat fluid level measures 18 x 17 x 23 cm. Fatty contents measure -150 Hounsfield units. There is a soft tissue nodule centered at the fat-fluid interface of the cystic mass is consistent with a Rokitansky nodule (dermoid plug).
Large volume ascites with selective sparing of the bowel and mesentery and scalloping of the liver contour suggesting peritoneal carcinomatosis.
Ovarian cystic teratoma containing a fat fluid level and a Rokitansky nodule (dermoid plug) which has been described to resemble a "Poké Ball" as illustrated.
The patient underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy and appendectomy.
Histopathology
Keratinizing moderately differentiated squamous cell carcinoma arising in an ovarian cystic teratoma/dermoid cyst. Involvement of ovarian surface, fallopian tube surface, uterus, pelvic peritoneum and appendix.
Case Discussion
- malignant degeneration of mature ovarian cystic teratoma with a fat-fluid level and a Rokitansky nodule within the cyst lumen. The CT appearance is characteristic of a mature ovarian cystic teratoma
- malignant transformation of ovarian teratomas occurs in 0.17-2% of cases 1,3
- squamous cell carcinoma, as seen in this case, is the most common type of histology seen in malignant degeneration (80% of reported cases) 4