Typical CT presentation of a mature cystic teratoma in a 53-years woman.

Clinical History

A 53-year-old woman lamented about abdominal pain, a sense of an abdominal mass and dyspepsia for 6 months, without regression through pharmacological treatment with PPI. She has no history of intervention nor known pathologies. She underwent a US and a CECT of the abdomen.

Imaging Findings

The abdominal US shows a capsulated inhomogeneous mass inside, occupying the four quadrants, without connection to the abdominal organs. At the CECT, the mass measured 23 x 17 x 12 cm. It has cystic features with liquid content, calcification inside, and some irregular nodules which moved while changing position. During the CT, we decided to complete the diagnostic procedure with a scan in prone position, to prove and underline the presence of a fat-fluid level inside the cystic lesion. The mass occupied umbilical and hypogastric regions, without signs of invasion of abdominal organs. There seems to be a connection with uterus and left ovary, while the origin remains uncertain. No lesions are shown in other abdominal organs. The patient, after this result, underwent a surgical laparotomic intervention and the histological report was of a mature cystic teratoma with dental parts and hair.

Discussion

Patients with mature cystic teratoma (MCT) are usually asymptomatic, but may present with abdominal pain and/or a palpable abdominal mass and rarely with complications, such as the ovarian torsion. Mature cystic teratoma is typical for women of childbearing age [1, 2].
MCTs are often diagnosed on transabdominal or transvaginal ultrasound as a cystic lesion with a inhomogeneous content. Inside the cyst a densely echogenic mass, called Rokitansky nodule, which contains hair, teeth and fat, and which may cause acoustic shadowing, can be found. Other commonly described sonographic appearances include a fat-fluid level or a homogenously hyperechoic lesion [3].
CECT can be useful in the case of a large teratoma in order to evaluate the adjacent organs [3]. CT shows an excellent sensitivity in detecting MCT. In addition to detection of fat, gravity-dependent layering, palm tree-like protrusion and fat–fluid levels are other imaging characteristics of mature cystic teratoma; the fat-fluid level is present in nearly 10% of cases [4].
MRI is as accurate as CT to diagnose MCT: ESUR suggests to use a sagittal T2 and a set of transaxial T1, T2WI and Fat-Sat, without gadolinium, to find out if the mass is cystic or solid. It is recommended to use "problem-solving" sequences (DWI, ADC, CET1W) to analyze complex cystic or cystic-solid masses. T2w high or intermediate signal, with DWI restriction and ADC bright signal are typical of teratomas, as these features are specific for the presence of fat [5].
The treatment of MCT is usually surgical, both with laparoscopic and laparotomic approach. The surgical strategy is guided by imaging tumour size and by the presence of associated gynaecologic pathology. A laparotomic approach is used in larger tumours. The intervention could consist of ovariectomy in case of a large tumour, or cystectomy, in order to preserve healthy ovarian tissue, especially in young patients [6].
MCT is a benign condition that has a good prognosis if diagnosed early. In case of a large size tumour, it can be useful to have a complete view of the case with MRI or CECT before intervention. CT pattern of MCT is typical and the diagnosis can not be missed if there is fat sign, calcification and fat-fluid level. We propose a prone, late scan to prove the presence of fat-fluid level, which is a pathognomonic sign of MCT.

Differential Diagnosis List

Final Diagnosis

Mature cystic teratoma.

URL:	https://eurorad.org/case/14177
DOI:	10.1594/EURORAD/CASE.14177
ISSN:	1563-4086