A Giant Ovarian Mucinous Cystadenoma and Low-Grade Appendiceal Mucinous Neoplasm in a Post-Menopausal Woman

Background: Ovarian mucinous cystadenomas are benign cystic tumors which originate from the surface epithelium of the ovary and rarely present during late age. Low grade appendiceal neoplasms (LAMN) are some of the rarest appendiceal tumors and only make up 0.7-1.7% of appendiceal tumor cases. Case Presentation: A 61-year-old woman was referred to the clinic due to a large abdominopelvic mass and complaints of abdominal pain, shortness of breath, and post-menopausal bleeding. She was a multiparous woman (G4P5), 160.02 cm, 121.109 kg and has a BMI of 47.4 kg/m2. She had a history of hypertension, and a previous history of spinal tumor surgery. Imaging studies were significant for a 37 x 27 x 28 cm cystic mass originating from the left adnexa and smaller cysts originating from the right adnexa. Pap smear and endometrial biopsy were negative. Laboratory studies included CA125, CA19-9, and CEA. Those were found to be 11 U/mL (normal < 35 U/mL), 174 U/mL (normal < 34 U/mL), and 0.6 ng/mL (normal < 2.5 ng/mL in an adult nonsmoker) respectively. Given the large size of the masses and elevated CA 19-9, the patient was referred to gynecological oncology for further assessment. After consideration of the imaging, labs, and patient's symptoms, the treatment plan suggested was a total abdominal hysterectomy and bilateral salpingo-oophorectomy (TAHBSO) to remove the masses. During the TAHBSO, an incidental appendiceal mass was noted and an appendectomy was performed. The gross pathology report revealed that the adnexal masses were bilateral mucinous cystadenomas, and the appendiceal mass was a LAMN. The uterus with the cystic ovaries were found to weigh 11.3 kg and measure 45 x 40 x 30 cm. The large cyst measured 42 cm and the smaller cyst measured 7 cm. The appendix measured 4.5 x 0.7 x 0.7 cm with the LAMN measuring 1.5 cm. The LAMN involved the muscular wall, and the margins were negative. Accordingly, no further treatment was necessary. Conclusion: This case report brings forth a unique case of 61-year-old patient who presented with bilateral mucinous cystadenomas and a LAMN. Mucinous cystadenomas themselves comprise about 15% of ovarian tumors and LAMN make up less than 2% of appendiceal cancers.