# Struma ovarii mimicking ovarian malignancy: a case report

## TL;DR

A rare benign ovarian tumor called struma ovarii can mimic ovarian cancer due to symptoms like ascites and high CA125 levels.

## Contribution

This case report highlights the diagnostic challenge of struma ovarii presenting as ovarian malignancy.

## Key findings

- Struma ovarii can present with ascites and elevated CA125, resembling ovarian cancer.
- Surgical intervention confirmed the benign nature of the tumor in this case.
- The condition may be incidentally discovered in asymptomatic premenopausal women.

## Abstract

Struma ovarii is a rare form of monodermal ovarian teratoma composed predominantly of mature thyroid tissue. Although benign in most cases, it can present with ascites and elevated serum CA125 levels, mimicking ovarian carcinoma. We report the case of a 38-year-old woman with a complex ovarian mass, ascites, and an elevated CA125 level—an initial presentation highly suggestive of malignancy that was ultimately diagnosed as benign struma ovarii following surgical intervention. This case underscores how struma ovarii, though uncommon, can masquerade as ovarian cancer and may even be discovered incidentally in an asymptomatic, premenopausal patient.