The patient also had a posterior fossa metasisis (how they presented) which was resected.

Histology

Immunohistochemistry shows strong nuclear staining in tumor cells for TTF-1 and strong cytoplasmic staining for cytokeratins CK7 and BerEp4. There is also strong staining for CEA. No taining for cytokeratin CK20 is seen in tumor cells. This profile confirms an origin of tumor from lung.

FINAL DIAGNOSIS: Posterior fossa tumor: Metastatic moderately differentiated adenocarcinoma with features consistent with an origin from lung.