Solitary fibrous tumour of the oral cavity: clinicopathological and immunohistochemical characterization of three cases

Solitary fibrous tumour (SFT) is an uncommon mesenchymal neoplasm rarely located in the oral cavity. To characterize further oral SFT, we describe three new cases. Each tumour originated in the buccal mucosa of a middle-aged/elderly patient. Histological examination showed well-circumscribed tumours with densely cellular areas alternating with hypocellular areas in a variedly collagenous, vascular stroma. Mast cells were abundant. The spindle-shaped, neoplastic cells immunostained strongly for CD34 antigen and vimentin and weakly for bcl-2, but not for epithelial cell markers, alpha-smooth muscle actin, or neurofilament or S-100 proteins. Compatible with the virtual absence of mitoses and of marked nuclear atypia, the overall frequency of proliferating cells expressing Ki-67 was low. The expression of CD34 was useful in the differential diagnosis. The consistent location in the cheek and expansion of one tumour after local trauma does not preclude a traumatic element in the development of oral SFT.

Extrathoracic solitary fibrous tumors: their histological variability and potentially aggressive behavior

The histological variability of solitary fibrous tumors may contribute to the difficulty in diagnosing these neoplasms, especially when they arise in extrathoracic sites. Like intrathoracic lesions, the behavior of extrathoracic solitary fibrous tumors is currently unpredictable because these types of tumor have only recently been recognized. This study therefore was undertaken to examine the clinical behavior and histological, immunohistochemical, and ultrastructural features of 24 extrathoracic solitary fibrous tumors with long-term follow-up. The patients comprised 10 men and 14 women, between 30 and 85 years of age (mean, 51 years). Ten tumors were located in the retroperitoneum or pelvis, 5 in the trunk, 4 in the extremities, 2 in the orbital region, and 1 each in the kidney, uterine cervix, and meninges. All of the tumors showed a classic morphological appearance, diffuse and strong immunoreactivity for both vimentin and CD34, and variable reactivity for bcl-2. All 7 cases examined ultrastructurally contained fibroblasts and myofibroblasts. Six tumors contained multinucleated giant cells, and in 4 cases these lined pseudovascular spaces with mononuclear cells, thus resembling giant cell angiofibroma and giant cell fibroblastoma. Other potentially similar spindle cell neoplasms mixed with adipose tissue, such as dendritic fibromyxolipoma, lipomatous hemangiopericytoma, cellular angiofibroma, and spindle cell lipoma, were considered in the differential diagnosis. One tumor displayed atypical histological features in the form of increased cellularity and nuclear pleomorphism, but this patient has remained free of disease for 14 years. Another 2 patients developed local recurrences at 6 months and 5 years, and a further patient developed pulmonary metastases that were diagnosed after 7 years. These tumors lacked any atypical histological features in the primary lesions. No patient has so far died of the disease. In conclusion, most extrathoracic solitary fibrous tumors appear to pursue a benign course, although, because some have the potential to recur or metastasize, careful long-term follow-up is necessary for all patients.

Extrapleural solitary fibrous tumor: a clinicopathologic study of 24 cases

Solitary fibrous tumors (SFTs), rare in extrapleural sites, can present difficulties in diagnosis at these locations. From the files of the M. D. Anderson Cancer Center, we accessed 24 cases of extrapleural SFT (14 females, 10 males, ages 19 to 85 yr) obtained for clinical, histologic, immunohistochemical, and follow-up findings. Tumor locations included the head and neck (n = 12), the abdomen (n = 10), and the extremities (n = 2). Tumors were 2 to 25 cm in greatest dimension (mean, 8.2 cm) and were well circumscribed or encapsulated. Histologic features were typical of their pleural counterparts, e.g., bland spindle cells with some hypercellular areas and myxoid to hyalinized backgrounds. A hemangiopericytic vascular pattern was present in 19 cases and prominent in 11. Mitotic activity ranged from 0 to 4 counts per 10 high-power fields. Necrosis was seen in two cases. Focally increased cellularity was seen in seven cases and margins were positive in another seven cases. Spindle cells were positive for vimentin (19 of 19) and CD34 (18 of 20), and negative for cytokeratin (0 of 19). Fibroblastic differentiation was present in the three cases studied by electron microscopy. Flow cytometry in three cases revealed diploid cell populations. Follow-up for 19 cases (9 to 99 mo) revealed no evidence of metastasis, although one patient had residual tumor after an incomplete excision, and one patient died of unrelated causes. Histologic findings such as mitotic counts, necrosis, cellularity, and marginal status were not associated with outcome. We conclude that extrapleural SFTs are clinically and histologically similar to their pleural counterparts. Although the length of clinical follow-up was short (mean follow-up, 41.4 mo), recognizing these lesions is important because they typically follow an indolent clinical course if completely excised. Although CD34 is nonspecific, it is usually positive in SFTs and may aid in their diagnosis.

Solitary fibrous tumor of the lacrimal sac

PURPOSE

Solitary fibrous tumor is a rare spindle cell tumor arising in the pleura. We report two cases of this tumor occurring in the lacrimal sac.

METHODS

A 23-year-old man and a 34-year-old woman presented with a medial canthal mass. They underwent surgical excision of their tumors.

RESULTS

Solitary fibrous tumors were diagnosed by light microscopy, immunohistochemical study, and electron microscopy. Immunohistochemical staining showed that tumor cells were reactive with vimentin and CD34 and demonstrated no smooth muscle or neural differentiation (nonreactive with desmin and S-100 protein).

CONCLUSIONS

The findings indicate that solitary fibrous tumor can occur in the lacrimal sac and may recur locally if it is removed incompletely. To our knowledge, these are the first reported cases of solitary fibrous tumors occurring in the lacrimal sac.

Solitary fibrous tumor of the spinal nerve rootlet: case report and literature survey

Solitary fibrous tumor (SFT) is a rare tumor that arises most commonly in the pleura. Recent evidence indicated that it is a tumor that originates from mesenchymal, probably fibroblastic, cells and is not restricted to the pleura. This report presents a case of primary SFT occurring as a dumbbell-shaped tumor of the cervical spine (C4/5) in a 46-year-old Japanese female, probably originating from the spinal rootlet. The tumor was predominantly extradural, loosely attached to the dura mater, with a small intradural extramedullary part attached to the C5 anterior and posterior rootlets. Histologically, the tumor was predominantly composed of a haphazard proliferation of spindle cells separated by abundant collagen. Immunohistochemically, the cells were strongly positive for CD34, bcl-2 and vimentin, but were negative for S-100 protein, neuron specific enolase, cytokeratin and epithelial membrane antigen. The present case and review of the literature strongly suggest that SFT is an entity that should be considered in the differential diagnosis of tumors of the cerebrospinal region.

A solitary fibrous tumor in the perianal region with a 13-year follow-up: report of a case

A case of a solitary fibrous tumor (SFT) of the perianal region in a 62-year-old man is reported herein. The patient had undergone an abdominoperineal excision of the rectum for an anorectal tumor 13 years previously, and had been referred to our hospital for a perineal mass. Computerized tomography and angiography revealed a markedly hypervascular tumor measuring 11 x 8 cm in size in the pelvic cavity. After preoperative radiotherapy (total 58 Gy) and the embolization of the feeding arteries, he underwent an en bloc excision of the tumor. Microscopically, the tumor was composed of spindle shaped cells with a "patternless" arrangement in a collagenous background. There was immunohistochemical evidence that these cells were strongly positive for CD34, thus suggesting the tumor to be SFT. The previously resected anorectal tumor showed similar histological and immunohistochemical findings. The patient's recovery was uneventful.

Solitary fibrous tumour of the pancreas: a new member of the small group of mesenchymal pancreatic tumours

Solitary fibrous tumours usually occur in the pleura, but occasionally they appear in extraserosal soft tissues or parenchymatous organs, where their diagnosis often causes problems. This report describes a solitary fibrous tumour (SFT) of the pancreas in a 50-year-old woman treated by left-side pancreatectomy. The tumour showed immunocytochemical reactivity for CD34, CD99 and bcl-2. Because of its favourable prognosis, SFT must be clearly distinguished from leiomyosarcoma, the most frequent nonepithelial tumour of the pancreas. Other mesenchymal tumours that may occur in the pancreas include tumours of the peripheral nerve sheath, fibrous histiocytic tumours and rare vascular tumours.

Solitary fibrous tumor of the skin

Solitary fibrous tumor (SFT) is an uncommon mesenchymal tumor that typically arises in the pleural cavity. Comprised of spindled cells characteristically arranged in diverse architectural patterns, SFT histologically simulates a variety of benign and malignant mesenchymal tumors. The diagnosis of SFT has been refined by the availability of newer immunohistochemical markers such as CD-34 and factor XIIIa, facilitating the identification of SFTs arising in multiple extrapleural sites, including the skin. We describe three cases of primary cutaneous SFT, review the literature, and discuss the histologic and immunohistochemical differential of other cutaneous tumors that SFT can mimic.

Tumors of the skin composed of large cells with abundant eosinophilic cytoplasm

Tumors of the skin composed of large epithelioid cells displaying abundant smooth or granular eosinophilic cytoplasm are relatively rare, yet may constitute a source of diagnostic difficulties for pathologists. Lesions derived from various skin elements are represented in this group, including tumors originating from adnexal structures and connective tissue elements of the dermis. The large, pink-cell or epithelioid appearance of the tumor cells may be the result of attempts to recapitulate the phenotype of a cell line normally characterized by such morphological appearance, such as apocrine epithelium, or may result from secondary changes in the cytoplasm of the tumor cells, such as accumulation of autophagosomes in granular cell tumors. The characteristic pathological features of this group of tumors is the subject of this review, with special emphasis on their differential diagnosis and the morphological features that may be of help for practicing pathologists to arrive at a correct diagnosis.

Solitary fibrous tumor of the oral cavity: an uncommon location for a ubiquitous neoplasm

Solitary fibrous tumor is an uncommon soft tissue tumor initially reported in the pleura but recently described in other sites of the body. To date, only 5 examples of oral solitary fibrous tumor have been reported. Here, we describe 2 additional cases of this tumor in the oral cavity. The tumors were composed of small to medium-sized spindle cells with bland cytologic features; these cells were haphazardly arranged in highly cellular sheets or ill-formed fascicles as well as in hypocellular areas with hyalinized blood vessels. Both tumors contained blood vessels with a hemangiopericytomalike appearance and expressed vimentin, CD34, and CD99. One case was also strongly positive for bcl-2. The diagnosis of solitary fibrous tumor may be difficult inasmuch as it shares a number of histologic features with other soft tissue tumors. Awareness of its occurrence in the oral cavity is important so that confusion with other spindle cell neoplasms can be avoided.

Myxoid solitary fibrous tumor: a study of seven cases with emphasis on differential diagnosis

Focal myxoid change is a well-recognized feature of solitary fibrous tumor (SFT), but to date, predominantly myxoid examples of SFT have not been reported. We describe seven cases of SFT in which stromal myxoid change affected 50% or more of the tumor examined, thus obscuring typical diagnostic features. Patients ranged in age from 35 to 68 years old (median, 45 yr), with an equal sex distribution. Tumor locations included pleura, orbit, and periparotid subcutaneous tissue, as well as four cases in deep soft tissue (two in the abdominal wall and one each in the chest wall and thigh). Myxoid areas were identified grossly in four cases. Histologically, the lesions were composed of bland spindle cells disposed haphazardly or with a lacy or reticulated appearance in a myxoid, richly vascularized stroma These myxoid areas were punctuated by small cellular aggregates in four cases, and areas showing diagnostic features of SFT were present in five of seven primary excision specimens. Atypical features suggestive of malignancy were not present in any of the cases. Immunohistochemically, all of the seven cases stained positively for CD34 and CD99 (013), and all were negative for smooth muscle actin, desmin, S-100 protein, epithelial membrane antigen, and pan-keratin. There were no recurrences or metastases reported in four patients with limited follow-up (median duration, 19 mo). Recognition of this uncommon morphologic subset of SFT is important because of possible confusion, particularly in small biopsy specimens, with a variety of myxoid spindle cell neoplasms with different biologic potential. These include low-grade fibromyxoid sarcoma, myxoid synovial sarcoma, malignant peripheral nerve sheath tumor, low-grade myxofibrosarcoma, myxoid liposarcoma, myxoid spindle cell lipoma, myxoid neurofibroma, and so-called "hemangiopericytoma."

Parasagittal solitary fibrous tumor of the meninges. Case report and review of the literature

The clinical, radiologic and pathologic features of a case of parasagittal solitary fibrous tumor of the meninges are reported. The patient was a 44 year-old male who presented with a complex partial seizure and a history of headaches and confusion. Radiological studies showed a large extra-axial dural-based mass in the right parietal region, predominantly isointense with gray matter and hypointense with respect to white matter on T1-weighted images, and hypointense with respect to gray matter on T2-weighted images. At surgery, the mass was very vascular, quite firm and very adherent to the convexity. Histologically the tumor was composed of spindle-shaped cells growing in fascicles within a collagenous matrix. Solitary fibrous tumor of the meninges is a newly described entity, which should be kept in mind in the clinical and radiological differential diagnosis of extra-axial brain tumors.

Nodular fasciitis and solitary fibrous tumor of the oral region: tumors of fibroblast heterogeneity

OBJECTIVE

Fibroblastic proliferations of the oral cavity are extremely varied, yet they share certain features-spindle cell morphology, collagen synthesis, and fasciculation. Nodular fasciitis is a cellular fibroblastic lesion, uncommonly located in the oral submucosa, that shows smooth muscle actin (SMA) immunoreactivity. Solitary fibrous tumor expresses a CD34 fibroblast phenotype. The aim of this study is to report instances of nodular fasciitis and solitary fibrous tumor in the orofacial region and investigate immunohistochemical markers to compare and contrast fibroblastic phenotypic heterogeneity in these tumors.

STUDY DESIGN

Seven benign cellular fibrogenic tumors initially diagnosed as nodular fasciitis over a 10-year period were examined. Immunohistochemical markers, including S-100 protein, SMA, CD68, CD34, and vimentin, were used to further characterize these lesions.

RESULTS

All tumors occurred in adults, and the buccal mucosa was found to be the favored site. The spindle cells in these tumors showed phenotypic heterogeneity both within and between tumors. All were vimentin-reactive and harbored small populations of CD68-positive macrophage/dendrocytes. Five tumors were SMA-positive and CD34-negative; the tumor in one case was SMA-negative and CD34-positive, and that in another was SMA-positive and CD34-positive.

CONCLUSION

Although rare, nodular fasciitis and solitary fibrous tumor arise in oral submucosa, usually in the cheek. The histopathologic features and immunomarkers indicative of myofibroblastic differentiation are seen in nodular fasciitis, whereas solitary fibrous tumor is CD34-positive; however, one instance was found to be positive for both markers. All of these cases harbored subpopulations of CD68-positive cells. Immunomarkers are a valuable adjunct in differentiating nodular fasciitis from solitary fibrous tumor, yet some tumors may harbor heterogeneous fibroblast phenotypes.

Solitary fibrous tumor of the oral cavity: report of a case

A case of benign solitary fibrous tumor of the oral cavity is reported. The tumor occurred in the buccal mucosa of a 34-year-old woman. The surgically removed tumor was 1.5 x 1.2 x 1.0 cm in size and well circumscribed. Histologically, the tumor was composed of spindle-shaped cells that were predominantly arranged haphazardly. Hemangiopericytoma-like areas and collagenous areas were also noted. Immunohistochemically, the tumor cells were positive for CD34 and vimentin. To our knowledge, this is only the second report of solitary fibrous tumor involving the oral cavity.

A unique case of desmoplastic ameloblastoma of the mandible: report of a case and brief review of the English language literature

A unique case of desmoplastic ameloblastoma is reported from the clinical, radiographic, and histologic viewpoints. The patient was a 56-year-old man who complained of a painless swelling on the buccal aspect of the left mandible. Periapical and panoramic radiographs revealed a rounded, slightly radiolucent area with blurred osteosclerotic margins. Occlusal radiograph and computed tomography images disclosed buccal bone expansion outlined by thinned cortices. Computed tomography images exhibited an enhanced area in the anterior portion of the lesion. Interestingly, the coronal computed tomography images revealed a close relationship between the periodontal membrane of the left mandibular second premolar and the enhanced area. Biopsy specimens from the anterior portion of the lesion displayed typical histologic features of the desmoplastic variant of ameloblastoma. However, those from the posterior portion disclosed a large cystic formation. Oxytalan fibers were identified in the stromal tissue of the tumor, which suggested that the tumor arose from the epithelial rests of Malassez in the periodontal membrane of the related tooth. We also reviewed previously reported 41 cases. In 36 of 38 cases in which the location was specified, the tumor was found in the anterior to premolar region of the maxilla or mandible. A radiographic description was given in only 29 previous cases, 28 of which involved multilocular lesions. No cyst as large as the one in the present case was found among the previously reported desmoplastic ameloblastomas. Although the present case deviates from the usual desmoplastic variant of ameloblastoma in terms of locus, radiologic appearance, and cyst formation, it still meets the histologic criteria for this variant in both the stromal and epithelial components.

Fibrous histiocytoma and fibrous tissue tumors of the orbit

Fibrous orbital tumors present clinically and radiographically in a broad spectrum ranging from a benign mass, to locally aggressive tumor, to invasive malignancy. Pathologic analysis and diagnosis are often challenging, usually based on a combination of light microscopy, immunohistochemistry, and electron microscopic findings. Some light microscopic and immunohistochemical findings, however, are relatively characteristic. A storiform or cartwheel pattern and vimentin staining are characteristic of fibrous histiocytoma. A herringbone pattern is usually found in fibrosarcoma. A "patternless pattern" and CD34 staining is found most commonly in solitary fibrous tumor. CT and MR imaging findings, as well as clinical presentation, in fibrous orbital lesions are often difficult to distinguish from those of other orbital masses, although there may be useful clues. Benign fibrous lesions are usually well-circumscribed and may chronically remodel bone, whereas more aggressive malignant fibrous tumors tend to have infiltrating margins and may destroy bone on CT or MR imaging. With malignant fibrous masses, enhancement patterns on CT or MR imaging may be more inhomogeneous, with avascular or necrotic nonenhancing regions. At MR imaging, benign lesions tend to be homogeneous on T1, T2, and postgadolinium T1-weighted images, whereas malignant soft tissue lesions may change their pattern from homogeneous on T1-weighted images to heterogeneous with low signal septations on T2-weighted images. Low T2 signal comprising part or all of a fibrous lesion correlates with dense collagen fibers, with a less cellular matrix. Areas of hyperintensity on T2-weighted images correspond with a more cellular matrix of fibroblasts and other cells. Calcification within a tumor, however, may give a similar appearance. Thus, if a lesion has predominantly low signal on T2-weighted images, or less specifically has low signal septations, then a fibrous orbital lesion with high collagen content may be ranked higher in the differential diagnosis (see Figs. 2E and 3B). When T2 signal is intermediate-to-high, then one has a difficult time narrowing the differential diagnosis. Radiographically, distinguishing these lesions from other fibrous orbital lesions, as well as from other varieties of orbital masses, is difficult. Differential diagnosis of fibrous orbital masses includes all the fibrous lesions described in this article, in addition to schwannoma (Fig. 7), neurofibroma (Figs. 4 and 8), hemangiopericytoma (Figs. 9 and 10), rhabdomyosarcoma, meningioma, lymphoma, and metastasis (Figs. 11 and 12). A history of prior orbital irradiation for retinoblastoma or other tumors may raise the possibility of radiation-induced secondary tumors, such as MFH, fibrosarcoma, and osteosarcoma. Determining the extent of orbital involvement remains the primary goal of the radiologist. The final diagnosis still rests with the pathologist.

Solitary fibrous tumor of the liver with CD 34 positivity and hypoglycemia

We report a new case of solitary fibrous tumor (SFT) of the liver, an extremely rare neoplasm. Including the present case no more than ten cases are reported in the English-language literature. To date there is no definite proof of the origin of this tumor. Both mesothelial and fibroblas-tic genesis has been postulated. The monoclonal antibody CD 34 has recently been used for the characterization of SFT. SFT would appear to be histogenetically related to a CD 34 - positive fibroblastic stem cell. A 61-year-old woman was admitted to our department with epigastric and right hypochondriac pain, weight loss, and hypoglycemia. Ultrasonography and computed tomography demonstrated a large heterogeneous mass in the right hepatic lobe. A right hepatectomy was performed. The tumor weighed 2850 g and microscopic section revealed a peculiar random pattern, the so-called patternless pattern of spindle tumor cells separated by abundant thick collagen bands. The tumor presented a number of highly cellular areas composed of plump spindle cell with hyperchromatic nuclei and rare mitotic figures. Ninety percent of the neoplastic cells displayed strong immunoreactivity for CD 34/My 10. The postoperative course was uneventful and the patient is alive and well without recurrence 6 years after surgery.

Solitary fibrous tumour of the tongue

Solitary fibrous tumour (SFT) is a neoplasm most often localised in the pleura and peritoneum. The tumour is composed of spindled fibroblastic cells arranged in a haphazard way. Recently SFT has been described in many locations. Only one case of oral SFT has been described in the cheek: this is the second case of an oral SFT located in the tongue. The differential diagnosis must be made from many soft tissue tumours. SFTs stain strongly, in almost all cases, for CD34.

Fine needle aspiration cytology of gastric solitary fibrous tumor: a case report

BACKGROUND

Solitary fibrous tumors (SFT) occur mainly in the pleura and other serosal sites. However, they have been found in extraserosal sites and should be considered in the differential diagnosis (DDx) of any spindle cell lesion, including those in the gastrointestinal tract. In this report, we describe fine needle aspiration (FNA) cytologic evaluation of a gastric SFT, emphasizing the role of immunocytochemistry in the DDx.

CASE

Computerized tomography-guided FNA of a subserosal gastric mass in a 77-year-old female was performed. The moderately cellular smears showed neoplastic cells arranged in interlacing fascicles and in a "patternless" pattern. There was variable collagenous stroma. The cell block revealed a similar pattern, with a single mitotic figure. Nuclear atypia and necrosis were absent. The neoplastic cells were strongly reactive for vimentin and CD34, with weak focal reactivity for smooth muscle actin, suggestive of vessels in tangential section. They were nonreactive for muscle specific actin, desmin, S-100 and pancytokeratin. Other immunocytochemical markers were also studied.

CONCLUSION

SFT should be considered in the DDx of spindle cell lesion of the stomach. Cell block and immunocytochemical markers, especially CD34, were extremely useful in the diagnosis of SFT on FNA.

Solitary fibrous tumour of the larynx: report of a case

Solitary fibrous tumour is a particular kind of mesenchymal tumour, classically arising in the pleura. We report the first case arising in the larynx, associated with a metastasizing adenocarcinoma. The diagnosis is mainly histopathological, especially when strong immunoreactivity for the CD34 antibody is present.

Frequent expression of bcl-2 protein in solitary fibrous tumors

The distinction of solitary fibrous tumors from histologically similar neoplasms is often difficult because they rarely occur at a variety of extrapleural sites. CD34 immunoreactivity has recently been recognized to be an adjunct for the diagnosis of solitary fibrous tumors. However, it is now known that CD34 staining is not entirely specific for this entity. We evaluated 23 solitary fibrous tumors and 54 other spindle cell tumors often considered in the differential diagnosis for immunoreactivity using monoclonal antibodies directed against bcl-2 protein, which protects cells from apoptosis and CD34. The patients with solitary fibrous tumors comprised 11 men and 12 women, ranging in age from 35 to 85 years (mean, 57.6 years). Fourteen tumors arose in the pleura, four in the retroperitoneum, three in the superficial soft tissue and one each in the mediastinum and uterine cervix. Nineteen of 23 solitary fibrous tumors (83%), irrespective of tumor site, demonstrated diffuse cytoplasmic staining for bcl-2 protein. bcl-2 immunoreactivity was also observed in five of seven neurofibromas (71%), eight of 10 synovial sarcomas (80%) and one of three spindle cell lipomas (33%). CD34 immunoreactivity was present in all but one solitary fibrous tumor (96%), seven of seven neurofibromas (100%), three of three spindle cell lipomas (100%), five of five dermatofibrosarcomas (100%), three of three hemangiopericytomas (100%) and two of seven malignant fibrous histiocytomas (29%). To date, most of the pleural and extrapleural cases have not shown aggressive features. We suggest that bcl-2 protein can be used together with CD34 in the diagnosis of solitary fibrous tumor to distinguish this entity from other spindle cell neoplasms.

Pictorial essay: solitary fibrous tumor of the pleura

Solitary fibrous tumor of the pleura (previously known as benign fibrous mesothelioma or pleural fibroma) can have a wide variety of appearances on imaging examinations. This essay reviews some of the lesion's more dramatic features.