Abstract
Uterine leiomyomas are a heterogenous group of benign mesenchymal tumours. While diagnosis is usually achieved through clinical assessment and pelvic ultrasound (PU), atypical subtypes are not as easily recognisable and can be mistaken for malignant tumours such as leiomyosarcoma or ovarian carcinoma. We describe the case of a 41-year-old patient who presented with increasing bulk symptoms, urinary frequency and growth of a hydropic leiomyoma (HLM) of the left lateral and posterior uterine wall that had been known for 10 years, confirmed with previous biopsy. The tumour filled the entire pelvic cavity in PU and was increasingly difficult to delineate; therefore an abdominal hysterectomy without oophorectomy was performed. Gross tissue examination showed an irregularly enlarged, asymmetric uterus with an intrauterine subserosal mass and an extrauterine papillary tumour arising from the right and posterior uterine wall. The tumour measured 20 × 17 × 10 cm in size. Numerous smooth muscle nodules were observed within the uterus and extending into the extrauterine component in a continuous transition, exhibiting a benign, bland appearance. The nodules were separated by abundant edematous connective tissue with increased vascularization. Histopathological analysis revealed low mitotic activity with no evidence of nuclear atypia, pleomorphism, or necrosis. Immunohistochemical staining confirmed the diagnosis of a benign smooth muscle tumour. Our findings confirm a rare, benign smooth muscle neoplasm with both intrauterine and extrauterine involvement, and add to the existing literature regarding presentation, diagnostic and therapeutic challenges associated with HLM.