CASE 14387 Published on 07.06.2017

Mature teratoma with secondary infection: a rare complication

Section

Genital (female) imaging

Case Type

Clinical Cases

Authors

Fernanda Gomes, Sofia Carvalho, Teresa Dionísio, Vasco Mendes, Pedro Oliveira.

Guimarães, Portugal;
Email:fmfgomes2@gmail.com
Patient

37 years, female

Categories
Area of Interest Genital / Reproductive system female ; Imaging Technique Ultrasound, CT, PACS
Clinical History
A 37-year-old woman was admitted to the hospital due to a sustained fever during postpartum period (caesarean). Two weeks after partum she started complaining of suprapubic pain and fever. Antibiotherapy was introduced for a urinary tract infection, but she didn't improve. After ten days, she attended the emergency room with fever and WBCs of 21.9×103cells/uL.
Imaging Findings
A renal and pelvic ultrasound was requested as part of the diagnostic workup. A pelvic ultrasound revealed a round well-defined solid mass with heterogenous echogenicity at the retrouterine pouch (Fig. 1). It seemed to have a small calcification and a thin echogenic band, with posterior acoustic shadowing. The left ovary had normal morphology and the uterus was homogeneous.
Pelvic computed tomography (CT) was performed, confirming the presence of a retrouterine mass measuring 63 x 75 x 73 mm, containing fat attenuation and a tiny calcification, characteristic features of mature teratoma (Fig. 2). Additionally a thick enhancing wall was noted, as well as peritoneal fat stranding (Fig. 3, 4). These features were suggestive of a secondarily infected ovarian teratoma.
Discussion
There are three major categories in which most ovarian tumours can be included: surface epithelial-stromal tumours, sex cord-stromal tumours and germ cell tumours [1].
Mature cystic teratomas represent approximately 25% of all ovarian neoplasms and are the most common neoplasm (>95%) arising from the germ cell category [1, 2].
The most common complications are torsion (16%) and rupture (1-4%) [3, 4]. One of the rarest complications of ovarian teratomas is infection, occurring in only 1% of patients. Other complications include malignant transformation (2%) and autoimmune haemolytic anaemia (<1%) [3, 4].
The ultrasound appearance of cystic teratomas variably ranges from completely anechoic to completely hyperechoic [5].
Some features are considered specific, such as the presence of a mural hyperechoic named Rokitansky nodule (dermoid plug) and the “tip of the iceberg” sign concerning acoustic shadowing caused by multiple tissue interfaces, such as sebaceous material and hair within the cyst cavity [5]. Other common ultrasound manifestation is a dermoid mesh representing multiple linear hyperechogenic interfaces caused by hair fibres. Other common finding is the presence of a fat-fluid or hair-fluid level [5].
The diagnosis at CT and MRI (magnetic resonance imaging) isn´t a hard one, and both modalities are very sensitive for detection of intratumoral fat [6, 7, 8, 9]. CT was performed because the patient presented as an emergency. Moreover MR imaging is preferable, allowing accurate differentiation between teratomas and haemorrhagic cysts and does not use ionizing radiation. The presence of fat attenuation within an ovarian cyst is a diagnostic sign of mature cystic teratoma, being reported in 93% of cases [6, 7, 8, 9].
Other common CT findings are a fat-fluid level (12% of cases), presence of teeth and other calcifications (56–84% of cases), tufts of hair (65% of cases) and a Rokitansky protuberance (81%-91% depending on the series) [2, 7, 8, 9].
Exploratory laparoscopy was performed to further characterize the mass lesion, revealing an increased ovarian size and an adjacent mass with output pus and hair. This supports the hypothesis of infected teratoma. After surgical and antibiotic treatments, the patient improved rapidly.
The results of culture studies showed an infection by Staphylococcus caprae and the histological examination of the resected ovary revealed that the lesion was a bilinear mature cystic teratoma (Fig. 5, 6). In addition, an extensive inflammatory infiltrate with areas of suppuration was identified (Fig. 7).
Differential Diagnosis List
Infected ovarian teratoma
Immature teratoma
Mature teratoma with malignant transformation
Infected ovarian teratoma
Final Diagnosis
Infected ovarian teratoma
Case information
URL: https://www.eurorad.org/case/14387
DOI: 10.1594/EURORAD/CASE.14387
ISSN: 1563-4086
License