Small cell lung cancer (SCLC) rarely metastasizes to the ovary, and is difficult to diagnose given its overlapping clinical features and histological characteristics with primary ovarian cancer. Since therapies for SCLC and primary ovarian cancer differ, it is important to determine the original site of ovarian lesions. This report describes the differential diagnosis of metastatic from primary ovarian cancer. A 46-year-old Chinese woman with a history of SCLC, confirmed by transbronchial lung biopsy in August 2018, presented with abdominal distension in December 2018. Ultrasound examination and whole abdomen computed tomography showed one mass in each ovary. A provisional diagnosis of ovarian tumor was given. A palliative total abdominal hysterectomy and bilateral salpingo-oophorectomy was performed; and three postoperative courses of chemotherapies. The patient died from multiple organ failure in May 2019. Metastatic ovarian cancer from SCLC was determined based on characteristic histological and immunohistochemical staining.

Small-cell neuroendocrine carcinoma (SCNEC) of the ovary is a gynecological malignancy characterized by rapid progression and poor prognosis. SCNEC is divided into primary and metastatic tumor. Primary ovarian neuroendocrine cancer is extremely rare and has a low 5-year survival rate. This paper reports the clinical manifestations of a 58-year-old patient with primary ovarian Small-cell neuroendocrine carcinoma and the prognosis after surgical adjuvant chemotherapy. The prevailing literature on this carcinoma is also reviewed and summarized. Our analysis reveals that histopathological examination is the standard diagnostic tool for ovarian SCNEC. We also highlight the importance of comprehensive imaging evaluation, early pathological diagnosis and comprehensive aggressive treatment to the prognosis of patients.

•This report shows very rare cases of small cell carcinoma of the ovary, hypercalcemic type and pulmonary type.•Their chemo sensitivity is quite different. These two cases followed opposite clinical courses.•The first case (SCOHT) progressed rapidly, and showed resistance to chemotherapy and radiotherapy.•The second case (SCOPT) showed sensitivity to chemotherapy and radiotherapy although recurrence was repeated.