Advanced Stage Clear Cell Ovarian Carcinoma Mimicking Uterine Sarcoma Without Gross Residual Tumor During Primary Surgery: A Case Report

BACKGROUND: Clear cell ovarian carcinoma is rare and accounts for 1%-12% of ovarian epithelial carcinomas, depending on ethnicity. The prevalence of clear cell ovarian carcinoma in Asian, White, and Black women is 11.1%%, 4.8%, and 3.1%, respectively. Magnetic resonance imaging (MRI) shows that clear cell ovarian carcinomas are typically unilocular cyst-solid (34.9%) or multilocular-solid (41.4%); only 23.7% are solid with papillary projections. MRI can detect clear cell ovarian carcinoma with a sensitivity and specificity of 90% and 87%, respectively. Notably, sometimes ovarian masses have a solid feature and should be differentiated from uterine masses. Clear cell ovarian carcinoma has a better prognosis compared to serous carcinoma when diagnosed at an early stage, but it has a poorer prognosis at an advanced stage. The absence of a residual tumor is a favorable prognostic factor in patients with advanced-stage clear cell ovarian carcinoma. Herein, we present a case in which clear cell ovarian carcinoma was misdiagnosed as uterine sarcoma because imaging showed a mass with a solid uterine-like and necrotic area. In the present case, cytoreductive surgery was performed to remove the entire tumor and its infiltration to the sigmoid colon and left ureter. Hence, the patient had a better prognosis. CASE REPORT: A 57-year-old Indonesian woman presented to our hospital (Dr. Soetomo General Hospital) with post-menopausal bleeding, a large solid pelvic mass, and abdominal discomfort. The patient was diagnosed with uterine sarcoma due to the solid feature observed during ultrasonography and MRI. During the surgery, the mass was observed to originate from the left ovary, and primary debulking surgery with a multidisciplinary team was performed with zero residual tumor tissue. The tumor was histopathologically confirmed as clear cell carcinoma. CONCLUSION: MRI of clear cell ovarian carcinoma can be misdiagnosed as uterine sarcoma due to its solid feature. Additionally, the enlarged mass distorts the anatomical landmarks. Surgery with no residual tumor improves the prognosis for advanced-stage clear cell ovarian carcinoma.