<prompt> A 67 year nude smoker presents with haemoptysis and cough. Bronchoscopic biopsy revealed un-differentiated tumour. The immunohistochemical marker that can be most helpful is-CalretininVimentinCytokeratinGGt  <response>: TEXT BOOK OF PATHOLOGY HARSHMOHAN 6TH EDITION PG NO 16 Epithelial tumors are stained by pankeratin or cytokeratin high or low MW p 