Sections of brain tissue show a cohesive tumor composed of mucin-secreting cribriform glands. Tumor cells contain abundant eosinophilic cytoplasm, vesicular nuclei and prominent nucleoli. Frequent mitoses and central necrosis are present.
Immunohistochemical results show tumor cells stain: CK7-, CK20+, TTF1- and CDX2+
FINAL DIAGNOSIS: Metastatic moderately differentiated adenocarcinoma, consistent with colorectal primary.