title: Spindle cell carcinoma of head and neck: an immunohistochemical and molecular approach to its pathogenesis.
abstract: BACKGROUND
  Spindle cell carcinoma (SpCC) is a rare microscopic type of cancer of the mouth and oropharynx. Although SpCC is thought to arise from squamous cell carcinoma (SCC), it carries a worse prognosis.
  
  
  OBJECTIVE
  To find out the difference in immunohistochemical expression of cytokeratin, vimentin and smooth-muscle actin, and mutational alterations in the K-ras oncogene between the two tumours, in an attempt to characterise SpCC.
  
  
  METHODS
  Immunohistochemical analysis was performed by standard avidin-biotin complex method in 35 cases each of SpCCs and SCCs. DNA extracted from paraffin wax-embedded tumours was used for PCR followed by single-strand conformation polymorphism for mutational analysis of K-ras exon 1 and exon 2.
  
  
  RESULTS
  In the SpCC group, cytokeratin positivity was significantly higher in epithelial areas (52.2%) than in spindle cell areas (16.1%), whereas vimentin was more positive in spindle cell areas (18.7%) than epithelial areas (2.7%). Cells intermediate between epithelial and spindle cell areas were consistently positive for both cytokeratin and vimentin. Cytokeratin was found to be significantly more positive in SCC (72.6%) than the squamous component and spindle cell component of SpCC. In this study, no mutation was detected in the K-ras gene of either the SpCC or SCC group.
  
  
  CONCLUSIONS
  The spindle cell component of SpCC is intermixed with cells that are morphologically mesenchymal but express dual antigen-positivity characteristic of epithelial (cytokeratin) and mesenchymal (vimentin) cells. These, possibly, are cells in transition suggesting that SpCC may be a sarcomatous metaplasia of SCC.
authors.affiliation: Department of Pathology, Maulana Azad Medical College, New Delhi, India. rucihka257@yahoo.com
authors.forename: Ruchika
authors.initials: R
authors.lastname: Gupta
authors.forename: Sompal
authors.initials: S
authors.lastname: Singh
authors.forename: Suresh
authors.initials: S
authors.lastname: Hedau
authors.forename: Sonu
authors.initials: S
authors.lastname: Nigam
authors.forename: Bhudev C
authors.initials: BC
authors.lastname: Das
authors.forename: Ishwar
authors.initials: I
authors.lastname: Singh
authors.forename: Ashish Kumar
authors.initials: AK
authors.lastname: Mandal
mesh_terms: D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004252:DNA Mutational Analysis / Q000379:methods; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D011905:Genes, ras; D020022:Genetic Predisposition to Disease; D006258:Head and Neck Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D007633:Keratins / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D018807:Polymorphism, Single-Stranded Conformational; D011446:Prospective Studies; D014746:Vimentin / Q000378:metabolism
chemical_list: D000199:Actins; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D014746:Vimentin; D007633:Keratins