Solitary fibrous tumor of the oral soft tissues: a clinicopathologic and immunohistochemical study of 16 cases

Oral spindle cell neoplasms: a review of 307 cases

The infrequent exposure of pathologists to soft tissue spindle cell neoplasms coupled with overlapping histologic patterns can often make diagnosis challenging. We reviewed all nonodontogenic spindle cell neoplasms seen between 1982 and 2002 (86,162 total accessions). Diagnoses were reclassified according to current standards supplemented with immunohistochemistry. Of the 307 neoplasms reviewed (0.36% of total accessions), neural tumors were the most common benign entities, accounting for 21% of total cases. Kaposi's sarcoma was the most common malignancy, accounting for 67% of all cases. Diagnoses were revised for 57 cases. Schwannoma and neurofibroma were most commonly revised to palisaded encapsulated neuroma. There were 8 myofibromas and 1 inflammatory myofibroblastic tumor. There were no oral leiomyomas; that is, all 4 originally reported cases were reclassified as myofibroma, palisaded encapsulated neuroma, and solitary fibrous tumor. With the exception of Kaposi's sarcoma, oral soft tissue sarcomas were rare; most benign lesions were neural in origin. The relatively high prevalence of some tumors, such as myofibroma, likely reflects the use of immunohistochemistry in the diagnosis of spindle cell tumors.

Solitary fibrous tumor of the oral mucosa--morphological and immunohistochemical profile in the differential diagnosis with hemangiopericytoma

The objective was to investigate two cases of solitary fibrous tumor (SFT) of oral mucosa, emphasizing the differential diagnosis with one case of oral hemangiopericytoma (HPC), in terms of their morphological and immunohistochemical features. Solitary fibrous tumors showed cellularity and collagenization varying from area to area, focal perivascular hyalinization, scattered giant nuclei cells and abundant mast cells throughout the tumor. The hemangiopericytoma case exhibited thin-walled and dilated vessels lined with flat endothelial cells, identified by "staghorn appearance". Tumoral cells of solitary fibrous tumor exhibited immunohistochemical positivity for CD34, as well as endothelial cells. The hemangiopericytoma was positive only in endothelial cells. In solitary fibrous tumor, alpha-smooth muscle actin, h-caldesmon and laminin stained the wall vessels. In hemangiopericytoma, on the other hand, the wall vessels were positive only for laminin, which staining was also observed in perivascular tumoral cells. The morphological and immunohistochemical differences observed allowed us to infer these lesions constitute distinct entities.

Solitary fibrous tumor with malignant potential arising in sublingual gland

A rare case is described of a solitary fibrous tumor (SFT) with malignant potential arising in the sublingual gland. A 59-year-old man presented with a 4-month history of a slowly enlarging painless mass in the center of the floor of the mouth. The tumor was a well-demarcated, firm mass with a multicystic lesion. The tumor exhibited highly cellular areas of spindle cells with patternless architecture alternating with hypocellular areas. The tumor cells were positive for CD34 and bcl-2 as well as vimentin, and negative for epithelial, myogenic, neurogenic and histiocytic markers. The tumor cells formed multiple satellite nodules around dilated ducts in the multicystic lesion, indicating infiltrative growth. In addition, areas exhibiting higher cellularity with increased mitoses were noticed in the satellite nodules, although cellular atypia was not obvious. These findings led to a final diagnosis of SFT with malignant potential. There has been no recurrence or metastasis for 27 months after the surgery. Solitary fibrous tumor of the salivary gland must be differentiated from various spindle cell neoplasms including myogenic, peripheral nerve sheath, fibroblastic and fibro-histiocytic spindle cell neoplasms, hemangiopericytoma and myoepithelioma. In addition to characteristic morphological features, an immunohistochemical positivity for CD34 and bcl-2 may aid in the diagnosis of SFT.

Immunohistochemical localization of endothelial cell markers in solitary fibrous tumor

Solitary fibrous tumor (SFT) is an uncommon tumor first reported in the pleura, but recently described in other tissues. CD34, which is expressed in hematopoietic stem cells, endothelial progenitor cells and vascular endothelial cells, is observed in most SFT and some investigators believe that its expression is a definitive marker of this tumor. In the present study, the expression of vascular endothelial cell markers, such as vascular endothelial growth factor receptor (VEGFR)-1 (flt-1), VEGFR-2 (flk-1/KDR), Tie-2 and c-Met, was examined in SFT to clarify the relationship between SFT and endothelial cells. By immunohistochemical staining of tumor cells from 26 patients, VEGFR-1 was detected in 24 (92%), VEGFR-2 in five (19%), Tie-2 in 14 (54%), and c-Met, a specific receptor of hepatocyte growth factor (HGF) in 23 patients (88%). Furthermore, VEGFR-3 (flt-4) immunoreactivity was detected in eight of 26 patients (31%). In contrast, VEGF, VEGF-C and HGF, which are ligands for the receptors, were not localized in the SFT cells. These findings indicate that most SFT may closely relate to vascular or lymphatic endothelial cells and the endothelial growth factors may contribute to the growth of SFT in a paracrine manner.

A case of solitary fibrous tumor of the parotid gland: review of the literatures

We report a rare case of solitary fibrous tumor of the parotid gland. A 47-year-old woman presented with a 3-year-history of left-sided subauricular swelling. Computed tomographic scans and magnetic resonance images revealed a well-defined and dumbbell-shaped mass, measuring about 30 mm in its greatest dimension, in the left parotid gland. Because the tumor occupied both superficial and deep lobes of the gland, she underwent total parotidectomy with preservation of the facial nerve. The microscopic finding showed short-spindle and ovoid cells arranged in a haphazard pattern with interspersed thin collagen fibrils. Immunohistochemically, the tumor cells were strongly positive for CD34, bcl-2 and vimentin, whereas stains for S-100, cytokeratin, smooth muscle actin, collagen type IV and CD117 (KIT) were negative. On the basis of these findings, the tumor was diagnosed as solitary fibrous tumor. Her post-operative course was uneventful, and she is currently free from disease 14 months after surgery. Diagnosis, clinical behavior and treatment of solitary fibrous tumor are reviewed from perusal of the literature.

Solitary fibrous tumors of the pleura

Solitary fibrous tumor of the pleura is a mesenchymal tumor that has been increasingly recognized over the past few years. The tumor was initially described in the pleura, but it has been reported in many other sites lately. Although the majority of these tumors have a benign course, the malignant form still remains enigmatic. Indeed, the behavior of these tumors is often unpredictable and does not always correlate with histologic findings. In addition, benign tumors may remain unproblematic for several years before changing into a malignant form. In order to define more precisely the clinical behavior of solitary fibrous tumors of the pleura, we reviewed the literature with particular attention to the clinical presentation, histopathologic characteristics, and cytogenetic differentiation of these tumors. A staging system and an algorithm for the management and follow-up of these patients are proposed.