Cystic pelvi-abdominal mass in pregnancy: An uncommon presentation of a subserosal leiomyoma

Uterine leiomyomas are common benign neoplasms. While generally easily diagnosed, variations in size and type of degeneration can drastically alter the imaging findings and result in diagnostic uncertainty. We present the case of a 34-year-old female with a large, cystic, pelvi-abdominal mass that was discovered in advanced pregnancy and misdiagnosed as an ovarian tumour. Intra-uterine demise of a viable foetus during an induction of labour and clinical deterioration necessitated further imaging and emergent surgical intervention. Further imaging, intra-operative findings and histopathological correlation revealed a pedunculated uterine leiomyoma with hyaline degeneration and areas of necrosis, complicated by left ovarian vein thrombosis. In addition to the intra-uterine demise, the unfortunate outcome included a total abdominal hysterectomy and unilateral salpingo-oophorectomy in a young patient. Typical leiomyomas are easily detected with imaging, however the varied clinical presentation and imaging findings in degenerating leiomyomas can prove a diagnostic challenge. This case describes a rare manifestation of a common condition and its subsequent diagnostic dilemma resulting in dire foeto-maternal outcomes. KEYWORDS: Leiomyoma; Hypercalcaemia; Ovarian Vein Thrombosis; Pregnancy; Intra-Uterine Foetal Demise.