Immunohistochemical evaluation and biological role of stromal myofibroblasts in odontogenic keratocyst, dentigerous cyst, and ameloblastoma: A comparative study

Abstract

Context: Stromal myofibroblasts (MFs) are key cells for connective tissue remodeling and interact with epithelial cells and other connective tissue cells to control phenomena as tumor invasion and angiogenesis thereby contributing to their biological behavior. Aims: The study assesses the frequency of stromal MF in solid ameloblastoma (SA), odontogenic keratocyst (OKC), and dentigerous cyst (DC) and relates it to their biological behavior. Settings and Design: Ten cases of each lesion were taken and stained immunohistochemically for alpha-smooth muscle actin (α-SMA) which is a marker for stromal MF. Materials and Methods: Ten cases each of SA, OKC, and DC were included in the study. Cases of oral squamous cell carcinoma (SCC, n = 5) served as the baseline for comparison as they are aggressive lesions expressing increased number of stromal MFs. The frequency of MFs was assessed as the number of α-SMA-positive stromal cells in 10 high-power fields and presented as the mean number of positive cells per field. Statistical Analysis Used: Differences in the mean number of α-SMA-positive cell per field among SA, OKC, DC, and SCC were analyzed using one-way ANOVA test. Results: Counts showed that mean number of α-SMA-positive MFs in SA, OKC, and DC were 24.56 (±4.63), 21.37 (±4.17), and 8.03 (±2.15), respectively. Results showed that the mean number of stromal MFs in SA and OKC was significantly higher than that in DC (8.03 ± 2.15) (P < 0.05). The count of MFs in SA and OKC was not significantly different from that of SCC (25.06 ± 4.61) (P > 0.05). Conclusion: Activated MF participates in the matrix degradation process which is considered to be one of the main forces in tumor growth and invasion. Among odontogenic lesions, ameloblastoma and OKC (presently termed as keratocystic odontogenic tumor) are well known for their higher growth and recurrence potential. They tend to show burrowing growth pattern. Various studies have evaluated the epithelial factors responsible for their growth potential; we in our study have tried to relate the emergence of stromal MF to the biological behavior of these lesions. The frequency of stromal MF in OKC and ameloblastoma was almost similar to that in SCC, thereby implying that MF can contribute to the biological behavior of these odontogenic lesions.