Immunohistochemical expression of alpha-smooth muscle actin and glucocorticoid and calcitonin receptors in central giant-cell lesions.

BACKGROUND

Central giant-cell lesions (CGCLs) are reactive lesions that consist histologically of spindle-shaped stromal cells, (fibroblasts and myofibroblasts) loosely arranged in a fibrous stroma, multinucleated giant cells and mononuclear cells with haemorrhagic areas. This study identified the immunoexpression of alpha-smooth muscle actin in spindle-shaped stromal cells, and glucocorticoid and calcitonin receptors in multinucleated giant cells and mononuclear cells. Their association with the clinical and radiographic characteristics of these lesions was identified.

METHODS

Thirty-five cases of CGCLs were studied. Expression of alpha-smooth muscle actin, glucocorticoid and calcitonin was evaluated by immunohistochemistry. The labelling index was 100 times the quotient of the number of positive cells divided by the total number of cells of each type. Logistic regression analysis was applied.

RESULTS

Alpha-smooth muscle actin was positive (54%) for spindle stromal cells (myofibroblasts). A significant association was observed with root resorption (P = 0.004) and cortical bone destruction (P = 0.024). Glucocorticoid immunoexpression was positive for 99% of the giant cells and 86.7% of the mononuclear cells. Glucocorticoid immunoexpression in the mononuclear cells was associated with root resorption (P = 0.031). A longer evolution time was associated with lower immunoexpression of glucocorticoid (OR 12.4: P = 0.047). Calcitonin immunoexpression was positive in 86% of the giant cells. Immunoexpression of calcitonin was associated with age (P = 0.040).

CONCLUSIONS

Myofibroblasts are important components of CGCLs, stromal cells and alpha-smooth muscle. Actin immunoexpression was associated with root and cortical bone resorption.