Elastofibroma: a histochemical, immunohistochemical, and ultrastructural study of two patients

Abstract

Elastofibroma is a rare neoplasm. In this article, we report our study of the pathogenesis of fibrosis in elastofibroma. Three tumors obtained from two patients were selected. One patient was a 57-year-old Japanese woman who had a bilateral tumor, and the other patient was a 83-year-old Japanese man. All tumors occurred in the infrascapular region. Macroscopically, the cut surface of all tumors showed a poorly defined and whitish mass with yellowish foci. Microscopically, the tumor consisted of collagen fiber bundles, abnormal elastic fibers, and spindle cells suggestive of fibroblasts. Elastica-van Gieson and Masson-trichrome stain identified abnormal elastic fibers and abundant collagen fibers, respectively, in elastofibroma. Immunohistochemically, fibroblasts were positive for CD34 but negative for alpha-smooth muscle actin and h-caldesmon. Additionally, the cytoplasm of many fibroblasts was positive for TGF-beta in all tumors. Ultrastructurally, some fibroblasts with abundant organelles in one tumor were observed in the adjacent area to amorphous elastic mass and bundles of collagen fibers. However, no myofibroblasts were ultrastructurally identified in the tumor. Finally, our study supplies further evidence that elastofibroma may show the proliferation of CD34-positive fibroblasts and contain no myofibroblasts, and that fibroblasts may produce both abnormal elastic fibers and collagen fibers through the secretion of TGF-beta.

Elastofibromatous Changes and Hyperelastosis of the Oral Mucosa

“…The cells are unanimously positive for vimentin [23][24][25][26][27], and most react for CD34 [23,[25][26][27][28] or bone sialoprotein [25]. Positive reaction for other antigens, such as promin-2, Cx43, Factor XIIIa, MEF-2 transcription factor [23,27], and TGF-b [28] has been reported in some studies. They are considered as fibroblasts [28] or consistent with the CD34 ?…”

“…Positive reaction for other antigens, such as promin-2, Cx43, Factor XIIIa, MEF-2 transcription factor [23,27], and TGF-b [28] has been reported in some studies. They are considered as fibroblasts [28] or consistent with the CD34 ? dendritic and fibroblast-like cells of the reticular dermis and fibrocollagenous soft tissues that are thought to act as potential mesenchymal stem cells [26].…”

“…It has also been proposed that they may be periosteal fibroblasts, as elastofibromas are usually, although not always, found in the proximity of the periosteum [29]. In contrast, they are not myofibroblasts, as is shown by negativity for myogenic markers, such as actins, desmin, calponin, or caldesmon [23][24][25][26][27][28], as well as their ultrastructural features [23]. Tryptase positive mast cells [26] and CD105 positive blood vessels [21] have been implicated in the pathogenesis of the lesion.…”

Histochemical and immunohistochemical characteristics of elastofibromas

“…The same investigators also could not find positivity with actin and desmin and reported that the previously described myofibroblastic differentiation was not seen in their lesions [6]. Similar to Hisaoka et al, there are other publications defining actin and desmin negativity in elastofibromas and reporting them to be of fibroblastic nature and not myofibroblastic [4,5,8,13].…”

“…The real etiology and pathogenetic mechanisms of elastofibromas are still controversial. There are only a few studies in the literature investigating the histochemical, immunohistochemical, and genetic features to determine the pathogenesis [8].…”