Background
A serous tumor comprises of the surface epithelial-stromal tumor group of ovarian neoplasms, which mainly derived from epithelium of mullerin. They are mostly common neoplasms with a strong tendency to bilateralism. They account for half of all ovarian tumors. Mostly 60% of them are mostly benign (cystadenoma) in nature and, 10% of them are borderline and 30% part of them is malignant (cystadenocarcinoma) in nature. Cystic lesions of the ovary are most common during infancy and adolescence, which are hormonally active periods of development [1]. Cysts are mostly non-neoplastic in children and could be categorized as follicular, simple, and corpus luteum cysts. Ovarian cysts rarely grow immense. Ultrasonography scanning permits early detection and appropriate treatment. Occasionally, ovarian cysts reach enormous dimensions without raising any symptoms. A few cases of giant ovarian cysts have been sporadically reported in the literature [1]. We presented a case of a huge papillary serous benign ovarian cyst in an 18-year old girl, with characteristics of ovarian serous cystadenoma both grossly and microscopically.