The patient was further screened for primary malignancy. The brain lesion was surgically approached:
MICROSCOPIC DESCRIPTION: Sections of brain tissue show a moderately differentiated adenocarcinoma composed of glandular and papillary structures. Cohesive tumour cells contain abundant eosinophilic cytoplasm, oval vesicular nuclei and prominent nucleoli. Frequent mitoses and areas of necrosis are present. Immunohistochemical results show tumour cells stain CK7+ and TTF1+; consistent with primary lung adenocarcinoma.
DIAGNOSIS: Brain, left temporal lesion: Metastatic moderately differentiated adenocarcinoma; consistent with lung primary.