The patient went on to have a craniotomy and resection of the mass, although the patient had a known pulmonary mass.
MICROSCOPIC DESCRIPTION: Paraffin sections show fragments of a densely hypercellular tumour. This consists of papillary and glandular structures lined by a stratified arrangement of markedly pleomorphic cells with round and oval vesicular and hyperchromatic nuclei and a variable amount of pale cytoplasm. Several glandular spaces contain mucin. There are scattered mitotic figures. Necrotic debris is seen in the lumen of one gland.
Immunohistochemistry shows strong diffuse nuclear staining for TTF-1, strong cytoplasmic staining for carcinoembryonic antigen (CEA) and cytokeratins, AE1/AE3, CK7 and BerEp4 and strong membrane staining for epithelial membrane antigen (EMA). Occasional cells show strong reactivity for cytokeratin CK20. No staining for S-100 protein or synaptophysin is seen in tumour cells. The features are of metastatic moderately to poorly differentiated adenocarcinoma arising from lung.
FINAL DIAGNOSIS: Metastatic moderately to poorly differentiated adenocarcinoma arising from lung.
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