Cytologic diagnosis of central neurocytoma in intraoperative squash preparations: a report of 2 cases.

BACKGROUND

Central neurocytoma is a rare central nervous system tumor typically found in the lateral ventricles and at the spectrum pellucidum. Two patients with central neurocytoma underwent intraoperative frozen section diagnoses, and the cytologic evaluations are described.

METHODS

Case 1 was a 21-year-old female who complained about reduced visual acuity. Magnetic resonance imaging (MRI) showed enhancement of a ventricular tumor. Over 80% of the tumor was removed, but after 14 months' follow-up, the disease progressed and regrowth occurred. The patient had a second tumor resection with gamma knife surgery. Case 2 was a 30-year-old female who presented with headaches. An MRI showed an enhancement of a ventricular tumor, and complete tumor removal was achieved. Cellular samples of both cases typically revealed ill-defined cytoplarm, oval nuclei with finely granular chromatin and micronucleoli. A fibrillose matrix in the background was noted. A typical appearance of perinuclear halo was also recognized. In both cases histopathologic examination was consistent with a central neurocytoma. Immunohistochemistry of both tumors was synaptophysin(+), NSE (+), NeuN(+), GFAP(-), but MIB-1 labeling index was 3.4% in case 1 and 1.1% in case 2.

CONCLUSIONS

These are 2 illustrative cases in which the authors report cytologic evaluation of central neurocytomna in intraoperative preparations. These tumors possess distinct cellular features that help with the intraoperative distinction from other intraventricular tumors. Moreover, it should be emphasized that immunostains for neural markers are essential for distinguishing them from other clear cell tumors of the brain, especially oligodendroglioma and clear cell ependymomal neoplasm. A combination of imaging, cytomorphology and immunohistochemical features of central neurocytoma can help to differentiate this condition from other intraventricular tumors. It is thought that careful scrutiny of intraoperative preparations allows one to make a distinction.