Ovarian neuroendocrine carcinoma of metastatic origin: clues for diagnosis.

Neuroendocrine tumors of the ovary are rare and of uncertain histogenesis. They may be primary or metastatic. Pathogenesis of ovarian carcinomas remains unknown. We report the case of an ovarian large cell carcinoma expressing all neuroendocrine markers (CD56, chromogranin A, synaptophysin) that presented as a primary tumor and coexisted with a typical endometrial serous carcinoma also expressing one neuroendocrine marker (CD56). The 2 tumors had identical molecular mutational profiles as examined by next-generation sequencing. We propose that the ovarian neuroendocrine tumor was metastatic from an endometrial serous carcinoma with limited neuroendocrine differentiation.