Mature Cystic Teratoma Masquerading as Hydrosalpinx: An Imaging Pitfall

Abstract

Mature cystic teratomas, or dermoid cysts, are among the most common benign ovarian tumors seen in women of reproductive age. They usually show characteristic imaging findings such as calcifications, fat–fluid levels, or a Rokitansky nodule, which help in making the diagnosis. Occasionally, however, these cysts can appear atypical, with predominantly cystic components that resemble other adnexal pathologies, leading to diagnostic uncertainty.

We describe the case of a 24-year-old nulliparous woman who presented with abdominal distension and menorrhagia. Ultrasound and MRI showed a large cystic adnexal lesion with incomplete septations, initially thought to represent hydrosalpinx. Ultrasound-guided aspiration yielded clear fluid, but the lesion recurred, prompting surgical removal. Histopathology confirmed bilateral dermoid cysts, with the right-sided one being mostly cystic. On retrospective review, the MRI showed subtle fat–fluid levels that had been overlooked initially because of the lesion’s large size.

This case underscores the importance of carefully reviewing fat-suppressed MRI sequences to identify small fat components that may otherwise be missed. Recognizing atypical presentations of dermoid cysts is essential to avoid misdiagnosis, unnecessary procedures, and to provide accurate patient counseling and management.