Dermoid Cyst Complicated by Ovarian Torsion

Sylvia Lobo, MS4

Ilse Castro-Aragon MD

US and CT

CASE HISTORY

11 year old female presents with 3 days of lower abdominal pain, fever, nausea, and vomiting, and abdominal tenderness and guarding. Labs show leukocytosis with neutrophilia.

IMAGES: PELVIC ULTRASOUND DERMOID CYST• Pelvic ultrasound of

ovary of an 11 year old female showing an enlarged midline ovary with a largely anechoic cyst (blue arrow) with linear septation (red arrow) and thickened echogenic parenchyma (yellow arrow) consistent with a diagnosis of complex ovarian cyst, complicated by ovarian torsion. Differential diagnosis includes dermoid cyst, hemorrhagic cyst, and immature teratoma.

IMAGES: PELVIC ULTRASOUND DERMOID CYST

• Pelvic ultrasound of ovary of an 11 year old female showing an enlarged midline ovary with a largely anechoic cyst with linear septation and thickened echogenic parenchyma with lack of internal flow consistent with a diagnosis of complex ovarian cyst, complicated by ovarian torsion. Differential diagnosis includes dermoid cyst, hemorrhagic cyst, and immature teratoma.

IMAGES: CT DERMOID CYST• Axial CT of the abdomen

and pelvis of an 11 year old female showing an enlarged right ovary with a cystic lesion containing calcium (red arrow) and fat (yellow arrow), and free pelvic fluid (blue arrow) consistent with a diagnosis of dermoid cyst, complicated by ovarian torsion. Differential diagnosis includes dermoid cyst, hemorrhagic cyst, and immature teratoma.

IMAGES: CT DERMOID CYST• Coronal CT of the

abdomen and pelvis of an 11 year old female showing an enlarged right ovary with a cystic lesion containing calcium (red arrow) and fat (yellow arrow), and free pelvic fluid (blue arrow) consistent with a diagnosis of dermoid cyst, complicated by ovarian torsion. Differential diagnosis includes dermoid cyst, hemorrhagic cyst, and immature teratoma.

IMAGES: CT DERMOID CYST• Sagittal CT of the

abdomen and pelvis of an 11 year old female showing an enlarged right ovary with a cystic lesion containing calcium (red arrow) and fat (yellow arrow), consistent with a diagnosis of dermoid cyst, complicated by ovarian torsion. Differential diagnosis includes dermoid cyst, hemorrhagic cyst, and immature teratoma.

CLINICAL FOLLOW UP

Following exploratory laparotomy with right ovary detorsion, right salpingo-oophorectomy with removal of right mass, and ovarian tumor staging the patient showed improvement in pain with resolution of nausea, vomiting, and fever.

Pathology revealed mature cystic teratoma with torsion, and no tumor cells on cytology of pelvic ascites, cyst fluid, and peritoneal washing.

IN A NUTSHELL • Most common manifestations

• Cystic lesion with hyperechoic Rokitansky nodule (dermoid plug) projecting into cyst lumen• Mass with diffuse or partial echogenicity, with an attenuated echogenic area of sebaceous material and hair• Multiple thin, echogenic bands due to the presence of hair, seen as the “dot dash pattern”

• Other less common manifestations• Fluid fluid levels caused be sebum floating on aqueous fluid• A single or multiple globules of fatty tissue, seen respectively as “Poké ball sign” and the “floating balls sign”• Calcification

• Potential Complications• Ovarian torsion• Cyst rupture• Hemorrhage• Peritonitis• Malignant transformation

• Remember • Remember that size >10cm or irregular borders (cauliflower appearance) are cause for suspicion of malignant

transformation

VOICE RAD MODALITY AND DISEASE

by Dr. Castro-Aragon, 2020

OLA

Which answer choice is the most common complication of dermoid cyst?

A. Malignant transformation

B. Cyst rupture

C. Ovarian torsion

D. Tumor metastasis

OLA

Which type of malignancy is most common secondary to malignant transformation of a dermoid cyst?

A. Basal cell carcinoma

B. Squamous cell carcinoma

C. Adenocarcinoma

D. Sarcoma

OLAWhat is the best next step in diagnosis based on this image?

A. CT with contrast

B. Color Doppler imaging

C. MRI

D. Laparoscopy

IMAGING SPECTRUM of DERMOID CYST

Pelvic ultrasound of a 13 year old female showing a large simple appearing cyst (red arrow) in the left ovary, consistent with diagnosis of dermoid cyst complicated by ovarian torsion. Differential diagnosis includes follicular cyst and serous cystadenoma.

IMAGING SPECTRUM of DERMOID CYST

Pelvic ultrasound of a 9 year old female showing an enlarged right ovary containing a large cyst (red arrow) with septations (yellow arrows) and an associated hypoechoic structure with a central area of echogenicity or calcification on posterior of ovary, consistent with diagnosis of dermoid cyst, complicated by torsion. Differential diagnosis includes twisted pedicle, regarding the round, ovary-adjacent structure.

IMAGING SPECTRUM of DERMOID CYST

Pelvic ultrasound of a 17 year old female showing an enlarged left ovary containing a complex cystic mass with an echogenic component consistent with fat (red arrow), a small cystic component (yellow arrow), and linear echogenicities(green arrows) consistent with diagnosis of dermoid cyst. Differential diagnosis includes hemorrhagic cyst and serous cystadenoma.

DISCUSSION

• Decreased or absent internal Doppler flow in the ovary may be seen in cases of ovarian torsion; although ovarian torsion is the most common complication of mature teratoma, decreased or absent flow on ultrasound with evidence of mature teratoma is not sufficient to definitively diagnose torsion, especially because lack of internal flow is characteristic of mature teratoma. Definitive diagnosis of ovarian torsion can only be made upon direct visualization of the rotated ovary in surgery.

• Additionally, presence of internal Doppler flow in a mass otherwise suspicious for mature teratoma indicates a high likelihood that the mass is not a mature teratoma, and may be a malignant mass or other type of benign mass.

LINKS AND REFERENCES

• National Guidelines• ACR

• Consistent References• Radiographics• Radiopaedia Mature Cystic Teratoma

• Other Journals and Texts• Up to Date Ovarian and Fallopian Tube Torsion• Up to Date Ultrasound Benign vs Malignant Ovarian Masses• Up to Date Pathology and Clinical Manifestations