Myofibroblasts in Odontogenic Cysts and Tumors: An Immunohistochemical Study

OBJECTIVE: The objective of this study was to assess immunohistochemically the presence of myofibroblasts both qualitatively and quantitatively in odontogenic cysts and tumors and to compare with the control cases of squamous cell carcinoma and to correlate the results with biologic behavior of these lesions. MATERIALS AND METHODOLOGY: Formalin-fixed, paraffin-embedded blocks of odontogenic cysts and tumors were retrieved from institutional archives. The sample size is 40; these include ten cases of odontogenic keratocyst (OKC) (n = 10), five cases of dentigerous cyst (n = 5), ten cases of solid ameloblastoma (n = 10), and five cases of unicystic ameloblastoma (n = 5). Ten cases of squamous cell carcinoma (n = 10) served as control. Sections were taken and stained immunohistochemically using alpha-smooth muscle actin for evaluation of myofibroblasts. The number of positive stromal cells was evaluated both for quantitative and qualitative analyses. RESULTS: The present study showed that the mean number of myofibroblasts among the odontogenic cysts and tumors was higher in locally aggressive lesions such as OKC (23.79 ± 19.95), solid ameloblastoma (26.38 ± 17.00), and unicystic ameloblastoma (20.74 ± 14.86) which were comparable to squamous cell carcinoma (21.49 ± 9.76) when compared to benign lesions like dentigerous cyst which showed the least number of myofibroblasts (13.1 ± 7.71). Qualitatively, the staining intensity of myofibroblasts showed a significant variation within the same lesion and among different lesions. There was a distinct difference in the morphology, pattern of arrangement, and distribution of myofibroblasts among the studied lesions. CONCLUSION: We conclude that the increase in the number of myofibroblasts could be one of the contributory factors for the locally aggressive behavior of benign lesions such as ameloblastomas and OKCs. Further studies are suggested to understand the mechanism by which these important cellular elements exert their effects on stromal and epithelial tissue compartments.