A Complex Case: Solid Unilateral Ovarian Mucinous Carcinoma Masquerading as Leiomyosarcoma in Postmenopausal Women

Introduction Ovarian cancers are the third most common gynecological and 8th most common cancer in women, associated with high mortality rates globally.Case Presentation A 60-year-old postmenopausal woman presented to the Gynecological outpatient department with complaints of pain in the abdomen for 2-3 months and loss of appetite with weight loss for 1-2 months. She was diagnosed as a case of uterine leiomyosarcoma or left adnexal mass on ultrasound and MRI. Intra-operatively, she was diagnosed with a unilateral left ovarian malignant mass, predominantly solid in consistency with metastasis to the left fallopian tube, uterus, cervical stroma, and omentum. The right ovary and tube were healthy. On histopathological examination, the final diagnosis of primary mucinous ovarian carcinoma was made. The patient tolerated staging laparotomy (total abdominal hysterectomy with bilateral salpingo-oophorectomy and infracolic omentectomy) well and was started on six cycles of adjuvant chemotherapy with Paclitaxel and Carboplatin injections along with Bevacizumab.Conclusion Primary mucinous ovarian carcinomas are rare and distinct subtypes of epithelial ovarian carcinomas. Due to their strong resemblance to other ovarian tumors and leiomyosarcoma, their diagnosis becomes challenging. Hence, it is crucial to consider leiomyosarcomas in the differential diagnosis of ovarian masses, especially in postmenopausal women.