Ovarian torsion as a complication of Brenner tumour

Clinical History

A 40-year-old woman with no relevant medical history was admitted to our hospital with the diagnosis of renoureteral colic. At emergency room (ER) she reported acute left flank pain and nausea. Both physical examination and laboratory tests were anodyne. During hospital stay an abdominal ultrasound was requested as a part of the diagnostic workup.

Imaging Findings

Ultrasound (US) disclosed a large (14 cm in size), rounded and well-defined solid mass, arising from the left ovary. The tumour had two distinct sonographic components: a hypoechoic internal part, with numerous tiny calcifications and acoustic shadowing (Fig.1), which was surrounded by a more homogeneous echogenic area, with small scattered cysts (Figs. 2 and 3). The left mesovarium was elongated and whirled in appearance (Fig. 4). The right ovary was normal, and the uterus was heterogeneous due to intramural leiomyomas. There was also moderate ascites. Contrast-enhanced multislice computed tomography (MSCT) confirmed the US findings; both axial (Fig. 5) and multiplanar reconstruction images (Fig. 6) disclosed a left adnexal tumour with torsion.

Discussion

Adnexal torsion is produced by the rotation of the ovarian vascular pedicle, which causes obstruction of venous and arterial flow. It may occur in a normal ovary or be associated to an underlying organic lesion. Ultrasound is the primary imaging modality for its evaluation; there are typical findings: unilateral ovarian enlargement; in 50-90% of cases there is an underlying ovarian mass; multiple small, uniform cysts aligned in the periphery; free pelvic fluid; and a twisted vascular pedicle. At colour Doppler sonography, both decrease and absence of venous flow have been reported (it depends on the degree of vascular obstruction and the chronicity of the torsion [5]), and also the “whirlpool sign” (visualization of coiled vessels of the twisted vascular pedicle) [1, 3].
If US is non-diagnostic, cross-sectional imaging (CT/MRI) is very useful. CT/MRI reveal uterine tube thickening, smooth wall/septal thickening only seen in twisted cystic adnexal masses, uterine deviation to the twisted side, lack of contrast enhancement of the internal solid component or thickened wall of the twisted ovarian mass, ovarian haemorrhage, peritumoral infiltration and ascites. Other recently discovered features include nonvisualised anatomic continuity with the ipsilateral gonadal vein [4].
The patient was referred to Gynaecology Department, and a left adnexectomy was performed. A large adnexal tumour was found, it had a violet surface and was twisted on its base. The microscopic study showed an oedematous ovarian parenchyma with haemorrhagic areas, epithelial proliferation neither atypia nor mitotic activity, surrounded by a fibrous stroma. The nets often showed small cysts, and the fibrous stroma had dystrophic calcification. Histopathological diagnosis was a benign Brenner tumour with oedematous and haemorrhagic signs probably due to ovarian torsion.
In this case, the ovarian torsion was a complication of a Brenner tumour. Brenner tumours are composed of transitional cells with dense stroma and represent about 2-3% of ovarian tumours. They are usually small (2 cm) and discovered incidentally, but patients may present with a palpable mass or pain. They are rarely malignant and can be associated with cystic neoplasms [1, 2].
Brenner tumours have a non-specific appearance at US, they tend to be solid, hypoechoic masses and can present calcifications. At CT, these lesions may be solid or a mixed solid-cystic tumour. The solid components are mildly or moderately enhanced. Extensive amorphous calcifications in solid components or in the wall are very characteristic. They have hypointense signal intensity on T2-weighted MR imaging due to calcifications and fibrotic tissues [6].

Differential Diagnosis List

Final Diagnosis

Torsion of adnexal Brenner tumour.

URL:	https://www.eurorad.org/case/13821
DOI:	10.1594/EURORAD/CASE.13821
ISSN:	1563-4086