Ovarian serous cystadenoma

Last revised by Karen Machang'a on 10 Oct 2023

Ovarian serous cystadenomas are a type of benign ovarian epithelial tumour at the benign end of the spectrum of ovarian serous tumours.

Serous ovarian tumours are traditionally described with a "cyst-" prefix because of their primarily cystic composition, e.g. cystadenoma, cystadenocarcinoma.

Serous cystadenomas account for ~60% of ovarian serous tumours 1. They are the commonest type of ovarian epithelial neoplasm. The peak incidence is at the 4th to 5th decades of life.

Generally asymptomatic. If symptoms are present, they are usually related to mass effect with displacement of adjacent structures, e.g. loops of bowel, adnexal torsion.

Thought to largely derive from ovarian epithelial inclusions, which itself is derived from fallopian tube epithelium.

They can be bilateral in ~15% of cases.

Serous cystadenomas are usually composed of unilocular (or at times multilocular) cysts filled with clear watery fluid. The cysts measure 10 cm in average diameter but may be extremely large. The lining of the cyst is flat or may contain small papillary projections. 

Composed of a solitary layer of benign epithelium which resembles fallopian tube mucosa and may form papillary structures. As with other serous tumours, psammomatous calcification can be a feature.

  • usually seen as a unilocular cystic/anechoic adnexal lesion
  • papillary projections are absent
    • if there is any wall irregularity, it is thin, with an acute angle with the cyst wall and has a regular surface 5
  • some lesions may contain sonographically detectable septations
  • no flow is detected on colour doppler
  • higher resistive and pulsatility indices on pulsed doppler when compared to malignant neoplasms

Often seen as a unilocular (typically) or multilocular cystic mass with homogeneous CT attenuation, with a thin regular wall or septum, and usually no endocystic or exocystic vegetation 1,4. Cysts can be quite large in size and have the potential to be seen filling most of the lower pelvis with extension into the upper abdomen.

The typical MR imaging appearance of serous cystadenoma is a unilocular thin-walled adnexal cyst 2. MRI may show a beak sign which may suggest an ovarian origin.

Signal characteristics within the cyst are usually homogeneous.

  • T1: cyst content is generally of hypointense signal in uncomplicated cases
  • T2: cyst content is of fluid (hyperintense) signal
  • T1 C + (Gd): enhancement of cyst wall sometimes occurs after contrast administration

They are benign lesions usually with a good prognosis. However, ovarian cystadenocarcinoma is thought to result from ovarian cystadenoma evolution into serous borderline tumours and invasive carcinoma. Surgical options include resection or oophorectomy. Cystadenomas do not recur following oophorectomy.

General imaging differential considerations include:

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