Radiological and histological features of MBL. (A) Post-gadolinium axial MR images show pseudonodular area of contrast-enhancement consistent with cerebellar neoplastic residual (arrow). (B) Post-gadolinium sagittal MR images show abnormal leptomeningeal enhancement (arrows) along the ventral surface of the mid-brain, cerebellar fissures and cerebral sulci due to leptomeningeal carcinomatosis. (C) Cerebrospinal fluid cytology shows the presence of large sized neoplastic cells that appear either singly or in clusters with rosette formation. (D) Hematoxylin&eosin staining of the primary lesion showing the presence of neoplastic cells large in size with marked anaplasia and large nuclei with evident nucleoli. Cell wrapping and necrotic phenaomena are also present (arrows). (E) Beta-Catenin immunohistochemical evaluation showing membrane and cytoplasmic positivity for beta-catenin with a negative nuclear staining. (F) p53 protein is overexpressed by neoplastic cells. (G) c-myc oncogene amplification (red spots) detected in neoplastic nuclei (blue) and centromere 8 signals (green spots) using CEP8/BAC as FISH probes. The white box highlights a nucleus in detail where 10 red spots are coupled with two green spots. (H) Coronal reformatted CT scan shows two subcutaneous metastases (arrows) with intact underlying calvarial bone. (I) Coronal T2-weighted MR image shows voluminous extracranial metastases on the edge of the collection at the site of the former sub-occipital craniotomy, with fascial and muscular infiltration.