Ovarian teratoma with torsion: An unusual cause of acute abdominal pain in the emergency department

A 51-year-old woman presented to the emergency department with severe acute low abdominal pain associated with nausea and vomiting. 

Her past medical history was unremarkable.
Clinical examination revealed only pain in the lower abdominal palpation. Laboratory results displayed a brisk leucocytosis with no other relevant features.

Pelvic ultrasound (US) depicted a heterogeneous, ill-defined, mass in a left retro-uterine location with a small amount of free fluid and a considerable discomfort associated with the probe pressure (Fig.1). Abdominal and pelvic computed tomography (CT) to better characterize these findings was performed and depicted a well-defined heterogeneous tumour in the left adnexal region measuring up to 7.2 cm (Fig. 2). This tumour contained mostly macroscopic fat and solid tissue with small parts density (Fig.3). In the upper pole of this lesion, one can notice the twisted ovarian pedicle (Fig. 4). The diagnosis of an ovarian teratoma with torsion was proposed by the radiologist. The patient was evaluated in the gynaecology department, followed by surgery.
The pathologic diagnosis of the surgical specimen confirmed the proposed hypothesis with the diagnosis of a mature teratoma with hemorrhagic necrosis due to torsion (Fig.5).

Background

Ovarian teratomas constitute the most common germ cell neoplasm (1). Although benign, these tumours can be associated with a set of complications from rupture, malignant degeneration, or, most commonly, torsion [1].

Clinical Perspective

Adnexal or ovarian torsion is an uncommon but severe cause of lower abdominal pain [2]. It is usually challenging to distinguish from other more common acute abdominal conditions such as appendicitis, diverticulitis, or renal colic [2,3]. Symptoms of ovarian torsion are non-specific [4], and clinical and laboratory evaluation shows a low accuracy for its diagnosis [3].

Large, heavy cysts and cystic tumours, such as mature teratomas, can predispose to ovarian torsion [4].  

Imaging Perspective

Since adnexal torsion is an uncommon condition, with non-specific clinical and laboratory findings, imaging is essential in establishing this diagnosis.

US is usually the first examination performed in the emergency setting. Although non-specific, most common US findings of ovarian torsion include an enlarged ovary, an ovarian mass, free fluid, thickening of a cyst wall, and twisted ovarian pedicle [3]. Color Doppler enables one to look for the "whirlpool sign," the typical swirling target appearance of the vessels in the twisted pedicle. This sign, associated with an enlarged ovary, is diagnostic for ovarian torsion.

The most commonly found US features of an ovarian teratoma are: a cystic lesion with a hyperechogenic projection into the cyst lumen; a diffusely or partially echogenic mass, as in our case; or multiple thin, echogenic bands in a cyst cavity

CT features of adnexal torsion may include fallopian tube thickening, wall thickening of the twisted adnexal cystic mass, engorged blood vessels on the twisted side, ascites, and uterine deviation to the twisted side [2]. The twisted ovarian pedicle can be challenging to detect. Although not often diagnosed on imaging, a twisted pedicle is pathognomonic when seen and therefore is the most specific feature of ovarian torsion [3].

Fat attenuation within a cyst at (CT) is diagnostic of ovarian teratoma. 

Conclusion:          

Ovarian teratomas can be associated with a set of complications, more frequently torsion. In fact, of the various ovarian neoplasms, benign cystic teratoma is considered to be the most common cause of adnexal torsion. 

Since ovarian torsion has non-specific clinical and laboratory findings, imaging is essential in establishing this diagnosis. Radiologists play an essential role in the emergency setting, distinguishing this relatively uncommon situation from other, more common, causes of acute abdominal pain.