Spindle cell carcinoma of head and neck: an immunohistochemical and molecular approach to its pathogenesis.
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.
Gupta
Ruchika
R
Department of Pathology, Maulana Azad Medical College, New Delhi, India. rucihka257@yahoo.com
Singh
Sompal
S
Hedau
Suresh
S
Nigam
Sonu
S
Das
Bhudev C
BC
Singh
Ishwar
I
Mandal
Ashish Kumar
AK
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
D000199:Actins; D004273:DNA, Neoplasm; D009363:Neoplasm Proteins; D014746:Vimentin; D007633:Keratins