Immunohistochemical evaluation of myofibroblasts in odontogenic cysts and tumors: A comparative study.
BACKGROUND
Myofibroblasts are fibroblasts with smooth muscle-like features characterized by the presence of a contractile apparatus and found in the connective tissue stroma of normal tissues such as blood vessels and lymph nodes. They are now thought to play a role in the synthesis and reorganization of extracellular matrix, which could contribute to the aggressive biologic behavior of the lesions.


OBJECTIVE
To compare the mean number of stromal myofibroblasts in dentigerous cysts (DCs), keratocystic odontogenic tumor (KCOT) and ameloblastoma; and to derive a correlation between the stromal myofibroblasts and the known biologic behavior of the lesions.


METHODS
A cross-sectional immunohistochemical analysis of cases of DC, KCOT and ameloblastoma.


METHODS
Twenty paraffin-embedded tissue blocks each of DC, KCOT and multicystic ameloblastoma were selected for the study and diagnosis confirmed through hematoxylin and eosin staining. Tissue sections were analyzed for the number of myofibroblasts using alpha smooth muscle actin (α-SMA) immunostaining.


METHODS
Differences in the mean number of α-SMA positive cells in each group were analyzed using one-way ANOVA test. Intergroup comparisons of mean values of α-SMA positive cells were performed using Mann-Whitney U-test.


RESULTS
Ameloblastoma showed the highest number of myofibroblasts, whereas DC showed the lowest. Among the groups, there were significant differences between the myofibroblast counts among DC and KCOT and between DC and ameloblastoma, whereas the difference in counts was not statistically significant between KCOT and ameloblastoma. A positive correlation was observed between the myofibroblast count and the known biologic behavior of the lesions.


CONCLUSIONS
Myofibroblasts may act in close association with the epithelial cells to bring about changes in stromal microenvironment, favorable to the growth and progression of the lesion. They may be of great value in predicting the biologic behavior and growth potential of such lesions.
Department of Oral Pathology and Microbiology, Amrita School of Dentistry, Amrita Vishwa Vidyapeetham University, Kochi, Kerala, India.
Deepa
D
Syamala
Department of Oral Pathology and Microbiology, Amrita School of Dentistry, Amrita Vishwa Vidyapeetham University, Kochi, Kerala, India.
Rakesh
R
Suresh
Department of Oral Pathology and Microbiology, Amrita School of Dentistry, Amrita Vishwa Vidyapeetham University, Kochi, Kerala, India.
Mahija
M
Janardhanan
Department of Oral Pathology and Microbiology, Amrita School of Dentistry, Amrita Vishwa Vidyapeetham University, Kochi, Kerala, India.
Vindhya
V
Savithri
Department of Oral Pathology and Microbiology, Amrita School of Dentistry, Amrita Vishwa Vidyapeetham University, Kochi, Kerala, India.
Prem P
PP
Anand
Department of Biostatistics, Amrita School of Medicine, Amrita Vishwa Vidyapeetham University, Kochi, Kerala, India.
Amrutha
A
Jose
Ameloblastoma; dentigerous cyst; keratocystic odontogenic tumor; myofibroblasts; smooth muscle actin