ORIGINAL ARTICLE

Spindle cell carcinoma of head and neck: an immunohistochemical and molecular approach to its pathogenesis

Ruchika Gupta¹, Sompal Singh², Suresh Hedau³, Sonu Nigam¹, Bhudev C Das³, Ishwar Singh², Ashish Kumar Mandal¹

¹ Department of Pathology, Maulana Azad Medical College, New Delhi, India
² Department of ENT, Maulana Azad Medical College, New Delhi, India
³ Division of Molecular Oncology, Institute of Cytology and Preventive Oncology (ICMR), New Delhi, IndiaDr A K Mandal, Department of Pathology, Maulana Azad Medical College, New Delhi 110091, India;

Correspondence to:
Dr Ruchika Gupta 162 Pocket-B, Sarita Vihar, New Delhi-110076, India; rucihka257{at}yahoo.com

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.

Aim: 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.

Abbreviations: dCTP, deoxycytidine triphosphate; SCC, squamous cell carcinoma; SpCC, spindle cell carcinoma

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