Abdomen / Pelvis for Tuesday, April 8th, 2025

History

12 yo post-menarchal female with no significant medical history presenting to the Emergency Department with a 1 week history of worsening RLQ abdominal pain with intermittent nonbloody emesis.

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Question

What is the diagnosis?

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Correct answer

Ovarian cyst complicated by ovarian torsion

Discussion

This post-menarchal patient had a large right 10 cm serous cystadenoma complicated by right ovarian torsion.

Ovarian masses have 3 different origins: sex cord-stroma, germ cell, or surface epithelium-stroma. Serous cystadenomas are derived from the surface epithelium-stroma. While these lesions are considered benign, large masses can predispose to ovarian torsion, which our patient presented with.

In post-menarchal adolescents, simple and complex ovarian cysts are common, with the majority being physiologic (functional) cysts. Other masses, whether benign or malignant, are rare and serous cystadenomas and mature teratomas are the most common.

A serous cystadenoma typically has benign features on ultrasound, all of which are congruent with the findings for this patient:

• Unilocular cystic or anechoic adnexal lesion
• Absence of papillary projections
• No flow on color doppler

On the images provided for this case, the torsed and enlarged right ovary can be identified on CT by the presence of follicles. On the US with doppler, the torsed ovary demonstrates absence of blood flow.

The management for serous cystadenomas in premenopausal patients is typically surveillance with one to two additional abdominal ultrasounds; however, this patient developed ovarian torsion due to the size of the ovarian cyst, which required an ovarian cystectomy. Surgical pathology confirmed the diagnosis of serous cystadenoma with hemorrhage and necrosis, consistent with ovarian torsion.

Differential diagnosis

For smaller ovarian cysts:

• Follicular cysts
• Corpus luteum cysts

Mature teratoma

Ovarian mucinous tumors

Serous cystadenocarcinoma

Paraovarian cysts

Endometrioma

References

• Weerakkody Y, Walizai T, Machang'a K, et al. Ovarian serous cystadenoma. Reference article, Radiopaedia.org (Accessed on 06 Mar 2025) https://doi.org/10.53347/rID-14473
• Hochberg L, Hoffman MS. Adnexal mass. In: UpToDate, Connor RF (Ed), Wolters Kluwer. (Accessed on March 06 2025.)
• Laufer, MR. Adnexal masses: Evaluation in infants, children, and adolescents. In:UpToDate, Connor RF (Ed), Wolters Kluwer. (Accessed on March 06 2025.)