Abstract
Central neurocytoma/extraventricular neurocytoma is a central nervous system (CNS) tumor composed of uniform round cells with neuronal differentiation. The typical lesions of central neurocytoma/extraventricular neurocytoma are at the interventricular foramen of the lateral ventricles (central neurocytoma) or brain parenchyma (extraventricular neurocytoma). Mature teratoma is a benign germ cell tumor commonly found in young women. Herein, we report a 24-year-old female with neurocytoma in a mature teratoma of the right ovary. The histological examinations showed mature epidermis, skin appendages, adipose and bone tissues in the tumor; microscopic foci of immature cartilage tissues were also found in some parts. In addition, massive solid sheets and uniform round tumor cells were found in the neuroectodermal tissues, with the formation of neuropil-like islands. Immunohistochemical examinations showed that the tumor cells were synaptophysin- and NeuN-positive but GFAP-negative. Based on these findings, the woman was diagnosed with neurocytoma arising from mature ovary teratoma, with microscopic foci of immature cartilage tissues. This is the fourth case report of neurocytoma outside the CNS to date.