Introduction: Differentiation of fibroblasts to myofibroblasts is an initial and very important event in tumor genesis. Myofibroblasts produce proteinases that stimulate invasion in cancers. Due to the more malignant potential of oral squamous cell carcinoma (OSCC) compared to cutaneous squamous cell carcinoma (CSCC) , the aim of the present study was to compare myofibroblasts between OSCC and CSCC to understand whether myofibroblasts can help more malignant potential of OSCC compared to CSCC or not.

Materials &Methods: This cross-sectional study included 40 cases of OSCC and CSCC and 20 cases of normal skin and normal oral mucosa. Then, 4-micron sections of paraffin-embedded tissue blocks of studied groups were stained immunohistochemically with α-SMA antibody. Mean percentage of myofibroblasts was calculated in invasive fronts of OSCCs with CSCCs and also in normal samples and staining intensity of cells for α-SMA marker and distribution pattern of myofibroblasts were determined.

Results: The differences of average percentage of myofibroblasts in OSCC and CSCC compared to normal groups were significant (Pvalue=0.007and Pvalue=0.003 respectively), but when we compared OSCCs and CSCCs, the difference was not significant. Also, there were no significant differences between OSCC and CSCC with regard to staining intensity and pattern.

Conclusion: Different biologic behavior of OSCC compared to CSCC doesn’t depend on myofibroblasts and other factors can be involved.