Figure 1.

 Immunostaining in a frozen section of (A) low grade and (B) high grade glioma using the Ultrarapid-Ki67 kit. An additional clinical case demonstrating the usefulness of intraoperative Ki-67 is shown in (C–E). (C) Haematoxylin and eosin staining of a cortical tumour was inconclusive, leaving the differential diagnosis of primary brain tumour (preferentially meningioma, one mitosis/10 high power fields) and metastatic carcinoma. (D) A high Ki-67 labelling index ruled out low grade and benign tumours. (E) Additional rapid intraoperative pan-cytokeratin staining defined the tumour finally as a metastatic carcinoma.