A 78-year-old male presented to us with gait disturbance. Cranial gadolinium-enhanced MRI revealed a brain tumor occupying the area from the right caudate nucleus to the pallidum, which was visualized as a high signal intensity on T2-weighted images. Primary central nervous system lymphoma, glioblastoma, and metastatic tumor were considered in the differential diagnosis, and surgical removal of the tumor was performed for a definitive diagnosis. Intraoperative imprint cytology revealed the tumor to be composed of numerous atypical large lymphoid cells with large ovoid nuclei containing coarse chromatin and prominent nucleoli ; the cytoplasm in some of the cells contained vacuoles. Lymphoglandular bodies were observed in the background. Based on the cytological findings, the diagnosis of malignant lymphoma, large cell type, was made. Intraoperative rapid cytology is useful for histological the diagnosis of brain tumors.
