Figure 4From: Atypical primary meningioma in the nasal septum with malignant transformation and distant metastasis Histopathology of the recurred and metastatic tumours. (A) Atypical cells having round-to-oval nuclei, with prominent nucleoli and frequent mitoses in the nasal cavity recurring tumour. (B) The metastatic tumour had a higher mitotic index (up to 40 mitoses within 10 HPF) and Ki-67 labeling index (40%) than the primary tumour (×400, H&E). (C) Geographic tumoural necrosis and hemorrhage (×400, H&E).Back to article page