A 31-year-old woman with two prior pregnancies and deliveries presented to the emergency room with mild right lower quadrant and right lateral abdominal pain with no palpable masses, rebound tenderness, or organomegaly.
She has no relevant past medical history or contributory family history. Transvaginal and transabdominal ultrasound revealed a cystic mass 9.3 × 6.3 × 8.8 cm in the left adnexal region, a normal left ovary, and no identifiable right ovary. An intrauterine device was located in a normal-appearing uterus, displaced slightly to the right.
Doppler flow was normal. CT scan noted a 8.6 cm mixed-density mass containing fat, soft tissue, and calcifications occupying the left adnexal region and vesicouterine pouch (Figure 1). Diagnosis of a right ovarian benign cystic teratoma was made based on the identified mix of tissues in the cystic mass. CA-125 level was not assessed due to the tumor's benign characteristic appearance on imaging.
Laparoscopic ovarian cystectomy was performed on the right ovary with sparing of ovarian parenchyma and cystic capsule rupture upon dissection.
A retrieval bag was used to remove the cystic contents from the pelvic cavity. The right ovary was torsed upon entry into the pelvis but regained its color when the torsion was reversed (Figure 2).
Pathology report revealed a thin-walled cyst filled with a large mass of hair, bone-like elements, and yellow sebaceous material. The largest soft tissue fragment (Rokitansky protuberance) measured 6.5 × 3.8 × 3.2 cm and contained a polypoid fragment of pink-tan epithelium with underlying yellow adipose and portions of partially calcified hemorrhagic soft tissue suggestive of bone formation with cartilage.
A total of nine teeth were identified, with one canine, multiple molars, and others with non-distinct appearance (Figure 3). Cartilage, bony matrix complete with red marrow cells, muscle, sebaceous glandular tissue, and both keratinized and non-keratinized epithelium were seen microscopically in the specimen. No ovarian or fallopian parenchyma was identified.
Discussion
Benign ovarian teratomas, also known as dermoid cysts or mature teratomas, are cystic structures that contain mature or immature features of all three germ layers:
- Ectoderm (skin, hair, and if present, one or two teeth)
- Mesoderm (muscle, fat)
- Endoderm (mucinous or endothelium)
It is theorized that benign cystic teratomas arise from a single germ cell after its first meiotic division around 13 weeks gestation, resulting in a totipotent stem cell with a chromosomal makeup of 46,XX whose DNA does not match its host.1 Benign teratomas generally present from the ages of 25 and 50, are generally benign with a 1% risk of malignant transformation, and make up 25% of ovarian tumors and over 90% of all germ cell tumors.
Size may vary from millimeters to 25 cm in diameter, and the teratomas are usually incidentally discovered on pelvic exam, ultrasound, or CT scan. When symptomatic, dermoid cysts generally present with pelvic pressure or ovarian torsion.4
The American College of Obstetricians and Gynecologists (ACOG) reports that there is good and consistent evidence (Level A) for transvaginal ultrasonography as the recommended imaging modality. Ultrasound findings that should raise concern for malignancy include:
- Cyst size larger than 10 cm
- Presence of papillary or solid components
- Irregularity
- Presence of ascites
- High color Doppler flow5
Ultrasound typically reveals a dense echogenic area in a large cystic space. However, only 33% of dermoids present with this "typical picture."1 In practice, CT and magnetic resonance imaging of the pelvis are generally used to further assess benign cystic teratomas before intervention, revealing cystic structures, fat, sebaceous components, loculations, and/or teeth in 29% of cases.
Identification of teeth, a dermoid plug, or a fat/fluid level on imaging is diagnostic of benign cystic ovarian teratoma.6 A solid nodular area in the tumor known as a Rokitansky protuberance is located in the cyst wall and generally forms a nipple-like structure from which teeth can arise. Macroscopically, dermoid cysts have a smooth, pale wall with thick sebaceous fluid containing a tangle of hair with firm areas of cartilage and teeth. The fluid becomes solid at room temperature and has a characteristically strong, foul-smelling odor.1
Clinical management of adnexal masses should work with the goal of excluding malignancy despite the fact that most ovarian masses are benign. CA-125 is the most sensitive and specific marker to assess malignancy in postmenopausal women; in premenopausal women, CA-125 is less useful, but extreme values can be helpful in determining malignancy. ACOG recommends using CA-125 levels along with clinical features to determine malignant risk.5
Surgical excision of dermoid cysts should be chosen if the masses are large, symptomatic, or growing in size on interval ultrasonography. If expectant management is chosen, regular follow-up ultrasound is recommended -- although around 25% of cases will need surgical intervention due to progressing symptoms. Ovarian cystectomy has a risk of decreasing ovarian reserve, and during the procedure, the physician should save as much ovarian parenchyma as possible.5
Chemical peritonitis poses a risk in dermoid cysts that have ruptured or perforated on excision, and thorough peritoneal lavage is advisable if this occurs.1 Follow-up should include ultrasound to monitor for recurrence, though ipsilateral recurrence is rare (3.4%) with contralateral occurrence more frequent (10%).5
It is agreed in the literature that the presence of teeth and bone is "rare," but has yet to be quantified. However, literature and case report review reveals that the incidence of more than two or three teeth in dermoid cysts is exceedingly rare and of interest both clinically and academically. It has also been concluded that expectant management of dermoid cysts does not result in an increase in the number of teeth produced, but is rather determined by the tissue's pre-disposition for production.
Of note, an increased number of teeth does not correlate with an increase in the malignant potential of the cystic teratoma.3 The presence of multiple teeth in a benign cystic teratoma is clinically relevant as it can make laparoscopic retrieval difficult, especially with a large Rokitansky protuberance. Generous peritoneal lavage should be used to avoid chemical peritonitis or increased risk of infection.
In this case, all of the aforementioned techniques were employed to minimize the patient's exposure to the contents of the ovary into her pelvis. Great care and extreme caution were used to suction the sebaceous fluid from the cyst from a small defect created in the ovarian capsule when the ovary was manipulated out of the pelvic cavity. The rest of the contents were removed as needed and placed into an endocatch bag for removal from the abdominopelvic cavity.
Copious irrigation was performed during and after the contents of the cyst were removed.
The patient recovered well without any postoperative issues.
Cory Albrechtsen is a student at Burrell College of Osteopathic Medicine in in Las Cruces, New Mexico; Darwana Ratleff-Todd MD, and Brianna Wellington MD, practice at Memorial Medical Center in Las Cruces.
References
1. Lobo RA, et al: Comprehensive Gynecology (7th ed.). Philadelphia, PA: Elsevier 2017; 412-415.
2. Hyman RA, et al: Ovarian Teratoma in Childhood. Diagnostic Ultrasound and Roentgenographic Correlation 1972; 16(3): 673-676.
3. da Silva TK, et al: A Set of Teeth in the Pelvis. Radiologia Brasileira 2015, 48(4): 263–264.
4. Park SB, et al: Imaging Findings of Complications and Unusual Manifestations of Ovarian Teratomas. Radiographics 2008; 28:969–983.
5. The American College of Obstetricians and Gynecologists (ACOG): Evaluation and Management of Adnexal Masses. Practice Bulletin No. 174, Nov 2016. Obstet Gynecol 2016; 128: e210-e226.
6. Dodd GD, Budzik RF: Lipomatous Tumors of the Pelvis in Women: Spectrum of Imaging Findings. AJR Am J Roentgenol. 1990 Aug; 155(2): 317-322.