The patient went on to have a laminectomy and excision of the mass. 


MICROSCOPIC DESCRIPTION: The sections show multiple small fragments which are composed of moderately atypical cells.  These have round, oval and angulated hyperchromatic nuclei and a variable amount of pale cytoplasm and are arranged in small solid islands within a fibrous stroma.  Scattered mitotic figures are noted.  An occasional poorly formed glandular structure is also identified.  The features are of metastatic undifferentiated carcinoma and are most consistent with an origin from lung. 

Tumour cells show strong nuclear immunostaining for TTF-1 and strong cytoplasmic staining for BerEp4, CK7 and cytokeratin AE1/AE3. No staining for CK20 is seen. This immunohistochemical profile indicates an origin from lung.

FINAL DIAGNOSIS: Spinal cord metastatic undifferentiated carcinoma with features consistent with an origin from lung.