Primary disseminated central neurocytoma: cytological and MRI evidence of tumor spread prior to surgery.

Since its description in 1982, central neurocytoma (CN) has been a relatively innocuous rare tumor of the central nervous system. Comprising of less than 0.5% of all intracranial tumors, most are reported to be slow growing, with low recurrence rates, and a favorable prognosis. Because of its rarity, its cellular biology, prognosis, and treatment strategies are difficult to ascertain. Its low-grade nature allows for continued growth before signs and symptoms of increase intracranial pressures ensue. Some authors theorize CN may derive from bipotential precursor cells of the periventricular germinal matrix, which are capable of both neuronal and glial differentiation, but maintain a low proliferative potential after birth. Several retrospective studies indicate that a MIB-1 index of greater than 2-3% will show a recurrence rate of 48-63%, respectively. Of hundreds of cases reported, the incidence of recurrence is very low, which makes aggressive forms of this tumor difficult to study. There are only 12 cases of craniospinal dissemination reported since its inception. The diagnoses of dissemination in these cases are made only after surgical intervention. We report the only case of primary disseminated CN, diagnosed on radiographic studies, and confirmed by cytology of the cerebral spinal fluid, prior to any kind of intervention. These cases may represent a subgroup of a more aggressive CN, which requires more assertive surveillance including CSF sampling and routine imaging of the neuroaxis.