CASE 1809 Published on 11.12.2002

Left ovarian Brenner tumour

Section

Genital (female) imaging

Case Type

Clinical Cases

Authors

S. Heye, D. Bielen, D. vanbeckevoort

Patient

66 years, female

Categories
No Area of Interest ; Imaging Technique MR, CT
Clinical History
A patient with a palpable left-sided intrapelvic mass. The patient had no complaints. Her medical history showed a hysterectomy 23 years earlier.
Imaging Findings
The patient was referred for an MRI examination, because of a palpable mass on the left side on endovaginal examination. The patient had no complaints. Her medical history showed a hysterectomy 23 years earlier.

Axial T1-weighted and sagittal T2-weighted MR images were obtained, followed by a contrast enhanced computed tomography (CT) scan.

On MR imaging a mass (4.5cm x 5.5cm) was seen in the left intrapelvic region, most likely in the left ovary. The mass showed a homogeneous isointensity on T1-weighted images and a uniformly hypointense signal intensity on T2-weighted images.

CT scanning demonstrated a solid mass with diffuse calcifications in the left ovary.

The right ovary was normal on both MR imaging and CT scans and no lymphadenopathies were found in the pelvic cavity. At laparotomy, an enlarged, hard left ovary and a normal right ovary were resected. Macroscopically, the tumour was solid, white in colour and showed some calcifications. Microscopically, the tumour showed abundant dens fibrous stroma with extensive amorphous calcifications. Within this stroma, several nests of solidly aggregated epithelial tumour cells were seen. No cellular atypia was noted. Some of these cells presented a clear cell cytoplasm. Small foci of endometriosis were also seen in the left ovary, at the border of the first tumour. Microscopically a small nodus with the same characteristics as the large one in the left ovary was found in the right ovary. Histopathologically, these were typical findings in a benign ovarian Brenner tumour.

Discussion
Brenner tumours account for 1.5-2.5% of all ovarian neoplasms and are usually diagnosed as incidental pathological findings (2). They arise from ovarian surface epithelium or pelvic mesothelium (coelomic epithelium) through a transitional metaplastic process ( 2,3). In 30% of cases an association with another epithelial ovarian neoplasm, including mucinous cystadenomas, serous cystadenomas, dermoid cysts, fibromas and simple cysts, can be found (3,4). Bilaterality is seen in 5-7% of cases (2). They are mostly asymptomatic, but symptoms such as lower abdominal pain, vaginal bleeding and a palpable mass have been reported (2). The vast majority of Brenner tumours are benign, with a few reports of borderline or malignant counterparts.

The median age of the patient at diagnosis is 45-50. The size of Brenner tumours varies from microscopic to huge, but most measure less than 5cm in diameter (2). Macroscopically, they usually appear as grey-white, solid and firm tumours (2). Microscopically, they are composed of abundant dense fibrous stroma with epithelial nests of transitional cells resembling those lining the urinary bladder. Extensive calcification may occur in the stroma as a degenerative change (2).

The ultrasonographic appearance of Brenner tumours is non-specific. They appear as solid hypoechoic masses, often with calcification (1).

CT findings can show a solid tumour or a mixed solid-cystic tumour, usually with calcifications in the solid parts of the tumour. These calcifications are frequently extensive and amorphous in appearance, but peripheral round calcification or cloudlike hazy granular calcification compatible with psammomatous calcification has been reported (2). Moon et al. demonstrated a mild to moderate contrast enhancement of the solid components of the Brenner tumour, but this enhancement pattern is not specific for Brenner tumour and is seen in other ovarian neoplasms.

On MR imaging, benign Brenner tumour typically displays homogeneous isointensity to the uterine muscle on T1-weighted images and markedly low signal intensity on T2-weighted images. Patchy mild enhancement on T1-weighted images after administration of gadolinium intravenously is also seen.

Differentiating benign Brenner tumour from fibroma and fibrothecoma can be difficult on MRI, but they have similar clinical implications because they are rarely malignant. Moreover, fibromas, when they are large, can show internal oedema and cystic changes and fibromas and fibrothecomas are associated with endometrial polyps and hyperplasia and not with ipsilateral (or contralateral) ovarian neoplasms (1,4).

Other differential diagnoses would include solid ovarian masses, such as benign teratoma, metastatic tumours of the ovary (Krukenberg tumours) and primary lymphoma. It would also include subserosal pedunculated or intraligamentous uterine leiomyomas and malignant Brenner tumours (2,3). Benign teratoma usually contains fat density and characteristic calcification consistent with teeth (2). Krukenberg tumour can contain hypointense components on T2-weighted images, but these are not of as low signal intensity as skeletal muscle or most fibromas. Krukenberg tumours are usually bilateral, with additional findings of primary malignancy (2,3). Primary lymphoma of the ovary usually shows a non-specific solid mass, but no calcification (2). Uterine leiomyomas display low or isointense signal intensity compared with the myometrium on T1-weighted images and low signal intensity on T2-weighted images, but they may be partially or completely hyperintense. This depends on the degree of cellularity, hyalinisation and haemorrhage. When demonstrating dystrophic-type calcifications, they usually have a mottled appearance with a curvilinear rim or appeared whorled and streaked (2,3,4). Malignant Brenner tumours consist of solid and cystic areas with necrosis and proliferating components. The solid components show marked patchy enhancement after administration of gadolinium intravenously (3). These findings could help in the differentiation of benign and malignant Brenner tumours, although Moon et al. postulated that there is no MR finding discriminating benign from malignant Brenner tumours.

In summary, benign Brenner tumours show typical imaging features on MRI and CT scanning. It must be kept in mind however that in 30% of cases an association with another epithelial ovarian neoplasm can be found, which may produce confusing MRI features.

Differential Diagnosis List
Left ovarian Brenner tumour
Final Diagnosis
Left ovarian Brenner tumour
Case information
URL: https://www.eurorad.org/case/1809
DOI: 10.1594/EURORAD/CASE.1809
ISSN: 1563-4086