A Large Pedunculated Subserosal Leiomyoma Masquerading as a Pelvic Tumor in Early Pregnancy: A Rare Case Report

Uterine leiomyomas, commonly known as fibroids, are the most prevalent pelvic tumors in females, affecting 20%-30% of women of reproductive age. However, large pedunculated subserosal leiomyomas presenting during early pregnancy are uncommon and may mimic adnexal or intra-abdominal malignancies, posing diagnostic and management challenges. This case presents a rare example of a large pedunculated subserosal leiomyoma in early pregnancy masquerading as a pelvic tumor. This report highlights the diagnostic challenge, intraoperative findings, and successful maternal outcome following timely surgical management. Here we present a case of a 31-year-old G3 P0 + 2 L0 woman who presented to our specialty hospital in Northern Tanzania at 11 weeks and 5 days gestational age (GA). She has a history of progressive abdominal distension for 1 year, associated with abdominal pain, vomiting, nausea, and early satiety. Initial abdominal ultrasound evaluation revealed a viable intrauterine pregnancy and a large heterogeneous abdominal mass with increased vascularity on Doppler ultrasound. Magnetic resonance imaging (MRI) identified a 21 × 10 × 15 cm, well-defined encapsulated mass extending intraperitoneally, abutting major abdominal vessels, consistent with a pelvic tumor. Explorative laparotomy revealed this mass to be a pedunculated subserosal fibroid arising from the uterine fundus through a narrow vascular stalk. Myomectomy was successfully performed with minimal blood loss and histopathological examination confirmed a benign leiomyoma with cystic degeneration. The postoperative course was uneventful. Subsequent follow-up at 25 weeks GA showed a viable intrauterine pregnancy with normal fetal growth.