Histochemical and immunohistochemical characteristics of elastofibromas.

Elastofibromas are slow-growing and rare soft-tissue tumors. The etiology and pathogenetic mechanisms are still controversial and there are only a few studies in the literature investigating the histochemical, immunohistochemical, and genetic features to determine the pathogenesis. We investigated the cellular composition of lesions with a diagnosis of elastofibroma in 17 patients by using histochemical and immunohistochemical methods. There were 17 cases with a mean age of 53.5 years. Mean lesion diameter was 6.6 cm. The immunohistochemical method showed vimentin and factor XIIIa positivity in all cases. Four cases had focal myoglobin positivity in the spindle-shaped cells between the collagen fibers. Spindle cells were positive for CD34 in 8 cases. Smooth muscle actin, desmin, type 4 collagen and laminin were negative in all cases. The elastic nature of the abnormal fibers was shown histoch with Verhoeff elastin staining and aldehyde fuchsin staining in all cases. Our results have shown that the concurrent positivity of factor XIIIa and CD34 in the cells forming the lesion might show that the lesionoriginates from primitive dermal mesenchymal cells. In addition, the myoglobin positivity found in some cases indicates the possibility of a myofibroblastic origin of elastofibromas.