A Case of Metastasis to Ovarian Tumor from Pulmonary Large-cell Neuroendocrine Carcinoma

Background. Ovarian metastasis from lung cancer is rare, with tumor-to-ovarian tumor metastasis even rarer. Case. A 79-year-old woman with a 1-month history of coughing was referred to our hospital. She was diagnosed with lung cancer as well as an ovarian tumor. Positron emission tomography/computed tomography (PET/CT) did not show any accumulation in the ovarian tumor, so we judged this lesion to be benign. The patient underwent surgical resection, and the pathological diagnosis was a pulmonary large-cell neuroendocrine carcinoma (LCNEC) pT3N1M0 stage IIIA. Thirteen months after surgery, the blood level of pro-gastrin-releasing peptide was elevated. A PET/CT scan showed a high fluorodeoxyglucose (FDG) uptake in the ovarian tumor. We suspected primary or metastatic ovarian cancer. Total hysterectomy with bilateral salpingo-oophorectomy and omentectomy was performed. The ovarian tumor was composed of mixed populations of spindle- and round-shaped tumor cells. The spindle-shaped tumor cells were diagnosed as forming an ovarian fibroma. However, the round-shaped tumor cells showed a morphology similar to that of the LCNEC with regard to positive neuroendocrine tumor markers according to an immunohistochemical analysis. Therefore, we diagnosed this as metastasis to an ovarian tumor from the LCNEC. Conclusion. We encountered a patient with a pulmonary LCNEC showing a tumor-to-ovarian tumor metastasis. We should consider the possibility of tumor-to-tumor metastasis for any benign tumor showing elevated tumor marker levels.