Solitary fibrous tumor of the orbit: Morphological, cytogenetic and molecular features

Abstract

Solitary fibrous tumor (SFT), a benign neoplasm arising in mesenchymal structures, was initially described in the pleura but subsequently has also been documented in other locations. It is uncommon in the orbit, where it closely resembles other benign spindle-shaped mesenchymal tumors of this area such as schwannoma, meningioma or hemangiopericytoma. We present a case of orbital SFT in a 34-year-old woman. The radiological study showed the presence of an enhanced uptake lesion measuring 2 cm in major diameter. The histopathological evaluation revealed alternating cellular and hypocellular areas with spindle-shaped cells. The cellular organization displayed a broad variety of irregular morphological patterns. The neoplastic cells were intensely positive for CD34 and vimentin, while S100, epithelial membrane antigen (EMA), Caldesmon, Calretinin and WT-1 proved negative. The pericellular matrix exhibited strong positivity for CD44 and collagen IV. Scarce mitotic figures, a Ki-67 nuclear labeling index of <5%, and focal expression of p53 were also observed. Measurement of DNA content revealed a DNA index of 1, indicating a diploid peak in 95% of the tumor cells. A normal 46,XX karyotype was present. No TP53 (exons 5-8) mutations or MDM2 and CDK4 amplifications were observed. No p14(ARF), p15(INK4B) and p16(INK4A) deletions or hypermethylation were observed in this benign tumor. Following surgical resection and radiotherapy, the patient showed no tumor relapse after one year of follow-up.

Solitary Fibrous Tumor of the Orbit: CT and MR Imaging Findings

“…15,16 The review of the literature reveals a recent trend of rather rapid accumulation of the number of orbital SFTs, and so far more than 50 cases of orbital SFT have been reported in the English-language literature. [10][11][12][13][14][15][16][17][18][19][20][21] Bernardini et al 15 questioned the rarity of orbital SFT. According to these authors, thanks to the widespread use of immunohistochemical studies, the number of orbital SFTs has rapidly been increasing after 1994 when the first orbital SFT was reported.…”

“…5,7,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Usually, the tumor is seen as a well-defined soft tissue mass with heterogeneously or homogeneously strong enhancement on CT and MR images. Occasional internal calcifications and necrosis have also been reported.…”

“…[2][3][4][5][6][7] Since the first report of 2 cases of orbital SFT in 1994, 8 the orbit has become one of the common sites of the head and neck involved by the tumor, and more than 50 cases of orbital SFT have been reported mostly in the ophthalmologic and pathologic literature. [9][10][11][12][13][14][15][16][17][18][19][20][21] To our knowledge, however, systematic analysis of the imaging features of orbital SFT has seldom been reported in the radiologic literature. The purpose of this study was to describe the characteristic CT and MR imaging findings of 6 cases of patients with SFT of the orbit proved on pathologic examination.…”

Value of MR Imaging in Differentiation between Solitary Fibrous Tumor and Schwannoma in the Orbit

“…1,2 Orbital solitary fibrous tumor was first recognized in 1994, and its histopathology has since been well-described. 1,[3][4][5][6] SFT demonstrates great variability in its morphology and shares histologic features with other benign mesenchymal tumors of this area such as schwannoma and hemangiopericytoma. 5 SFT demonstrates a strong level of diffuse immunoreactivity with a monoclonal antibody directed against the human hematopoietic progenitor cell antigen CD34; while most schwannomas and some of the hemangiopericytomas also can be CD34-positive, the CD34 immunoreactivity is generally weak in intensity and focal in distribution compared with that in SFT.…”

Molecular Biology of Unreresectable Meningiomas: Implications for New Treatments and Review of the Literature

“…69,70 Furthermore, the majority of malignant meningiomas have been shown to display alterations of CDKN2A, p14ARF, and CDKN2B, whereas these were infrequent in benign meningiomas. 61,[71][72][73][74] Similarly, in an expression analysis by Simon et al, 74 only $26% of grade 1 and 2, but 57% of grade 3 tumors lacked both p16 and p15 protein expression. In addition, 36% of nonmalignant but 71% of the anaplastic meningiomas lacked p14 protein.…”