Solitary fibrous tumor of the nasal cavity and orbit

Malignant Solitary Fibrous Tumor of the Nasal Cavity and Orbit: A Case Report

Solitary fibrous tumors are well-recognized in the pleura and their occurrence in the nasal cavity is uncommon. They show a hemangiopericytoma-like vasculature, a "patternless pattern" of growth, and lesions characterized by both hypercellularity and hypocellularity. As a malignant form of SFT, mesenchymal neoplasm is extremely uncommon and poorly understood, although there are no established standards for making this diagnosis, it is nonetheless accepted. It can develop either de novo or within an already-existing benign SFT, and there are few published accounts of the cytopathologic characteristics of these tumors.In this case, a patient complained of tenderness on the right nasal root and diplopia for six months. Here, we report on a case of malignant solitary fibrous tumors in the nasal cavity, which extended into the orbit, and review the radiologic and pathologic features.

A Large Solitary Fibrous Tumor of the Nasal Cavity and Paranasal Sinuses Involving the Anterior Frontal Fossa: A Case Report and Review of the Literature

The Solitary Fibrous Tumor (SFT) is a rare mesenchymal neoplasm that arises mainly from the pleura. The sinonasal tract is generally not affected by SFT, and less than 100 cases have been reported in the English literature to date. We report an extremely rare SFT of the nasal cavity and paranasal sinuses extending into the anterior frontal fossa through the floor of the anterior skull base. To our knowledge, this case is the fourth SFT of the sinonasal tract involving the anterior frontal fossa in the world. Meanwhile, the tumor, measuring 13 × 6 cm in images, is the largest SFT of the sinonasal tract compared to previously reported cases. Three surgical procedures, including a transcranial one, were performed for the patient to achieve complete removal of the tumor. The diagnosis of SFT was established primarily by immunohistochemical positivity for CD34, STAT6, and negativity for S-100 protein. We emphasize the possibility of recurrence in SFT, and close follow-up is necessary with the help of nasal endoscopy and imaging approaches.

Fate and Management of Incompletely Excised Solitary Fibrous Tumor of the Orbit: A Case Series and Literature Review

PURPOSE

There is an imperfect correlation between the histology and behavior of solitary fibrous tumor (SFT). In addition, recurrence is common, and dedifferentiation may occur over time. Preferred primary treatment is intact excision, but friable pseudocapsules and tenacious attachments can thwart this goal in the crowded, visually sensitive orbit. This study addresses the fate and appropriate management of incompletely excised orbital SFT.

METHODS

Among a single surgeon's 7-case experience with orbital SFT, 3 cases involved incomplete primary excision, either before (2 cases) or after (1 case) referral. We reviewed the clinicopathologic data in these 3 cases, with follow-up intervals of 18, 21, and 52 years after initial presentation. We reviewed the English-language literature on SFT, with special attention to evolving nomenclature, orbital involvement, recurrence, malignant transformation, and management options.

RESULTS

Benign versus malignant designations of SFT vary with histological and behavioral criteria. Approximately 150 orbital cases have been reported. Published rates of primary malignancy and recurrence across all histologic categories are 6% to 12% and 30% to 37%, respectively. We identified 43 well-documented recurrences (range, 6 months-33 years; median, 3 years) and 10 cases of histological dedifferentiation (range, 14 months-33 years). Because of SFT's rarity and needed follow-up intervals, the value of adjuvant therapy is not yet proven. In follow up of 18, 21, and 52 years after initial presentation, our 3 cases with incomplete excision showed either no recurrence (Case 1) or no morphological dedifferentiation (Cases 2, 3).

CONCLUSION

A treatment algorithm is predicated on the completeness of surgical excision and histological features. However, we recommend case-by-case multidisciplinary decisions in a tumor-board setting.

Orbit Solitary Fibrous Tumor: A Proposed Risk Prediction Model Based on a Case Series and Comprehensive Literature Review

Solitary fibrous tumors (SFTs) of the orbit are rare. In order to further characterize the clinical and pathologic features of solitary fibrous tumor arising at this anatomic site, 12 cases of orbital SFTs were analyzed in conjunction with a review of 263 cases reported from the English literature in order to develop a risk prediction model. SFTs of the orbit were equally distributed between males (n = 5) and females (n = 7) with a mean patient age of 46.8 years (median 44.5 years; range 18-76 years) at initial diagnosis. The patients typically presented with swelling or mass around the orbit, with proptosis (n = 10), ptosis (n = 5), and visual changes (n = 6). Tumors were orbital (n = 10) or upper eyelid (n = 2). Mean tumor size was 2.5 cm (median 2.6 cm). Microscopically, the tumors were characterized by cytologically bland spindle cells with patternless growth, hypocellular and hypercellular areas, variable amounts of collagen, and ectatic, branching blood vessels. By immunohistochemistry, all cases had a strong nuclear STAT6 expression. All patients were initially managed with excision or biopsy, three with presurgical embolization. The two patients with biopsy only had persistent disease (mean 37.2 months), but a third patient developed distant bone metastasis at 86.9 months. Overall mean follow-up was 73.1 months: 9 patients are alive or dead without disease (mean 77.9 months), two patients with persistent disease, and one patient with metastatic disease at last follow-up (102 months). Incorporating cases sufficiently reported in the literature, a risk prediction model based on age > 45 years, tumor size > 3 cm, tumor necrosis, mitoses of > 4/2 mm², moderate to high cellularity, and moderate to severe pleomorphism allows for risk stratification for the development of local recurrence and distant metastasis. In conclusion, orbital SFTs are rare, but can be reliably diagnosed based on the presence of characteristic morphologic features and STAT6 immunohistochemistry. Orbital tumors tend to show a higher frequency of local recurrence than distant metastasis, which can be predicted by a risk stratification model unique to orbital tumors. With late disease common, long term clinical follow-up is recommended.

Sinonasal Tract Solitary Fibrous Tumor: A Clinicopathologic Study of Six Cases with a Comprehensive Review of the Literature

Solitary fibrous tumors (SFTs) are well recognized in the head and neck region, but rarely arise in the sinonasal tract (SNT). Six primary SNT SFTs were identified in the files of Southern California Permanente Medical Group between 2006 and 2017. The patients included five males and one female ranging in age from 33 to 72 years (mean 52 years), most of whom presented clinically with nasal obstruction. Three tumors involved the nasal cavity alone, one involved the paranasal sinuses, and two involved both the nasal cavity and paranasal sinuses. Histologically, the tumors were characterized by a variably cellular proliferation of cytologically bland spindle cells within a collagenous stroma with prominent interspersed branching vessels. Mitotic activity was low (range 0-2 per 10 high power fields) and there was no evidence of pleomorphism or tumor necrosis. Surface ulceration was noted. By immunohistochemistry, the lesional cells were positive for CD34, STAT6 and bcl-2. Clinical follow up information was available for all patients (range 32-102 months; mean 72 months). There were no recurrences or metastases and all were alive with no evidence of disease at last follow-up. SFTs rarely affect the SNT, but should be considered in the differential diagnosis of SNT mesenchymal lesions. Immunohistochemical expression of STAT6 can aid in diagnosis and separation of SFT from other spindle cell lesions occurring at this anatomic site. In combination with cases reported in the literature, primary SNT SFT behave in an indolent manner with conservative treatment.

Update on Select Benign Mesenchymal and Meningothelial Sinonasal Tract Lesions

Several benign and malignant mesenchymal and meningothelial lesions may preferentially affect or extend into the sinonasal tract. Glomangiopericytoma (GPC, formerly sinonasal-type hemangiopericytoma) is a specific tumor with a predilection to the sinonasal tract. Sinonasal tract polyps with stromal atypia (antrochoanal polyp) demonstrate unique histologic findings in the sinonasal tract. Juvenile nasopharyngeal angiofibroma (JNA) arises from specialized tissue in this location. Meningioma may develop as direct extension from its intracranial counterpart or as an ectopic tumor. Selected benign mesenchymal tumors may arise in the sinonasal tract and pose a unique differential diagnostic consideration, such as solitary fibrous tumor and GPC or lobular capillary hemangioma and JNA. Although benign and malignant vascular, fibrous, fatty, skeletal muscle, and nerve sheath tumors may occur in this location, this paper focuses on a highly select group of rare benign sinonasal tract tumors with their clinicopathological and molecular findings, and differential diagnosis.

Ocular adnexal (orbital) solitary fibrous tumor: nuclear STAT6 expression and literature review

PURPOSE

To report the clinico-pathological features of solitary fibrous tumor occurring in the ocular adnexa (OA) in a single center. To assess the presence of NAB2-STAT6 genes fusion in OA solitary fibrous tumor detected by nuclear overexpression of STAT6.

METHODS

Retrospective study including orbital and OA solitary fibrous tumors treated between 2006 and 2014 in our center. The clinical, radiological, and histopathological findings were evaluated. STAT6 expression was assessed by immunohistochemistry.

RESULTS

Five patients were identified and presented with a chronic OA mass. The tumors were radiologically well delimited, highly vascularized and without bone erosion. All the patients underwent complete surgical excision. Pathological examination confirmed solitary fibrous tumor in all cases. All tumors demonstrated a nuclear expression of STAT6. There were no recurrences, with a mean follow-up of 5 years after surgery. Our review demonstrated that proptosis was the most common presentation occurring in 60 % of the cases. In the ocular adnexa, adverse histological criteria were found in 19.7 % of the tumors, and recurrences were observed in 48 % of these cases. Thirty-six percent of patients presented at least one local recurrence, and metastastic spread was found in 2.4 % of the cases. Tumor-related death was described in two cases.

CONCLUSION

Ocular adnexal SFT are rare and usually present as a chronic orbital mass with proptosis. In the OA, solitary fibrous tumor demonstrates STAT6 nuclear expression, as documented in other locations. Recurrences are unusual and metastasis exceptional. Initial surgical resection should be complete in order to avoid recurrence.

Orbital solitary fibrous tumor: a case series with review of the literature

PURPOSE

To report the clinical features, patient demographics, management, and outcomes of a series of patients with orbital solitary fibrous tumors (OSFTs) and provide a review of the English literature describing this rare entity.

DESIGN

A review of patient demographics, clinical presentations, imaging, histopathology, surgical management, and outcomes were analyzed.

METHODS

A non-comparative retrospective chart review of the demographics, clinical presentations, imaging, histopathological features, management, and disease outcomes of patients presenting to a tertiary orbital center with a tissue diagnosis of OSFT between 2007-2012 was performed along with a review of the English-language literature.

RESULTS

Our study included four male patients, with a mean age of 48 years at referral. The most common presentations included a slowly growing mass, globe displacement, diplopia on extreme gazes, and/or facial disfiguration. All tumors were analyzed with histopathology and immunohistochemistry. Treatment involved the complete surgical excision of the lesion, obtaining clear margins. All patients remain alive and well with no evidence of recurrence after a minimum follow-up of 15 months (range 15 months-5 years).

CONCLUSION

SFTs should be considered when confronting a painless slowly growing orbital mass that induces globe displacement and/or facial deformity. Imaging will show a well-defined lesion that enhances with contrast. A careful initial surgical excision with clear margins is required for adequate local control of the tumor, avoiding recurrence and potential malignant transformation.

Solitary fibrous tumor of the petrous bone: a successful treatment option

The patient was a 48-year-old man complaining about right hemicranial pain and deafness of 1 year's duration. MRI showed a solid well-vascularized mass destroying the mastoid and petrous bone, and with an epidural component that pulled the right cerebellar hemisphere. The patient underwent a right modified type A infratemporal approach, which allowed complete resection of the tumor, with a low morbidity. The pathological diagnosis was solitary fibrous tumor. The patient received complementary treatment with radiotherapy. At 24 months after the initial treatment the patient is free of disease. We conclude that solitary fibrous tumor of the petrous bone can be satisfactorily treated with surgical excision followed by radiotherapy, with low morbidity and excellent facial function. To our knowledge this is the first description of a solitary fibrous tumor of the petrous bone. Due to the lack of consensus in treating rare tumors, we want to offer this management approach for treating this kind of tumor.

Orbital solitary fibrous tumor : a case report and diagnostic clues

Orbital solitary fibrous tumor (SFT) is a rare tumor originating from the mesenchyme. We describe the clinical presentations, radiological and operative findings, and pathological features of a patient with orbital SFT. The patient was a 46-year-old female who presented with progressive proptosis advanced for 20 months. On ophthalmological examination, no visual impairment was detected, but left eye was found to be obviously protruded on exophthalmometry. Orbital magnetic resonance imaging showed a 2.5 x 2 x 2 cm, intensely enhanced mass in the left orbit, which compressed the eyeball forward and the optic nerve downward. The patient underwent frontal craniotomy with superior orbitotomy and gross total resection was performed for the tumor. The histopathological diagnosis including immunohistochemistry was a SFT. After the surgery, proptosis was markedly relieved without visual impairment. Although orbital SFT is extremely rare, it should be considered in the differential diagnosis of orbital tumors. Clinical presentations such as painless proptosis and CD34 immunoreactivity play a significant role in differentiating orbital SFT from other spindle-cell neoplasms of the orbit.

Solitary fibrous tumor in the cervical spine with destructive vertebral involvement: a case report and review of the literature

INTRODUCTION

Recently, solitary fibrous tumors occurring in spine-related lesions have been reported. However, the destruction of vertebral bodies by this type of tumor has not been reported.

MATERIALS AND METHODS

A 71-year-old female presented with pain from a mass on the right side of her neck. Plain radiographs of the cervical spine showed collapse of the C5 vertebral body and dislocation of the C4 vertebral body. The MRI image showed a large mass surrounding C4 and C5, which had low signal intensity in the T1W image and high signal intensity in the T2W image. At first, resection of the tumor and spinal fusion was performed by anterior approach.

RESULTS

Histology revealed a solitary fibrous tumor with proliferating spindle cells. Immunohistochemistry showed positive stains for vimentin and CD34. One year postoperatively, a local recurrence manifested extensive destruction of the C4 and C5 vertebral bodies. Then, palliative surgery with posterior cervical instrumentation and radiation therapy were performed. Because the destruction proceeded and the rods were broken 2 years after, she underwent additional occipito-cervical instrumentation.

CONCLUSIONS

This is the first report of a solitary fibrous tumor that involves the destruction of the spinal structure. An extensive destruction of the vertebral body by the solitary fibrous tumor needs to be aware in treating this tumor with spinal involvement.

Minimally invasive endoscopic techniques for treating large, benign processes of the nose, paranasal sinus, and pterygomaxillary and infratemporal fossae: solitary fibrous tumour

OBJECTIVES

We report an extremely rare case of a large solitary fibroma of the paranasal sinus, which we treated by sinonasal endoscopic surgery. We describe its clinical and histopathological features, and we report the endoscopic technique used to deal with such a large sinonasal mass (penetrating the pterygomaxillary and infratemporal fossae); we also offer a brief survey of the literature.

CASE REPORT

A woman presented with an approximately one-year history of nasal obstruction. Nasal endoscopy revealed an irregularly shaped, friable, reddish mass that occupied the whole of the right nasal fossa. Magnetic resonance imaging of the paranasal sinuses revealed a large mass that occupied the anterior and posterior ethmoids and the maxillary and sphenoid sinuses, displacing the septum and penetrating the pterygomaxillary fossa, having destroyed the lateral wall of the right nasal fossa. The tumour was resected by means of sinonasal endoscopic surgery; an endoscopic medial maxillectomy with extension to the pterygomaxillary and infratemporal regions was performed. Histological analysis confirmed the diagnosis of solitary fibrous tumour. During follow up, we performed regular nasal endoscopies, as well as computed tomography scans one and six months post-operatively.

CONCLUSIONS

Endoscopic techniques are currently the approach of choice for the treatment of such tumours of the sinonasal cavity and pterygomaxillary and infratemporal regions. The size of the lesion did not contraindicate endoscopic sinonasal surgery as a curative treatment.

Solitary fibrous tumor of the orbit: a case series

PURPOSE

Solitary fibrous tumor (SFT) occurs rarely in the orbit. We present four such cases, representing one of the largest case series reported to date of this rare orbital tumor.

METHOD

The four patients ranged from ages 20 to 50, all of whom presented with lid swelling or bulging in the involved eye. All four patients underwent CT scan to confirm the diagnosis of an orbital mass, which was then excised.

RESULTS

The tumors of all four specimens contained spindle-shaped cells with bland nuclei and rare mitotic figures. They all stained positively with CD34 and vimentin. Resection margins were positive in two of the four cases. One of these cases demonstrated residual tumor on follow-up CT scan, which remained unchanged at one-year follow-up. No evidence of residual tumor was found in the other three cases, despite one having malignant pathology.

CONCLUSION

SFT is a rare and generally benign tumor of the orbit. Immunohistochemical testing with CD34 is necessary to confirm the diagnosis. Although en bloc tumor resection is the definitive treatment, residual tumor may remain stable for some time. However, this must be followed closely if complete resection is not carried out.

Tumeur fibreuse solitaire de l’orbite : une cause inhabituelle d’exophtalmie unilatérale

BACKGROUND

The solitary fibrous tumor (SFT) is a spindle-cell tumor that very rarely involves the orbit. We report a new case that we compare to reports in the literature.

CASE

A 72-year-old woman presented a conjunctival inflammation of the right eye developing over 5 months with progressive proptosis. Magnetic resonance imaging revealed an extraconal and homogeneous mass, which showed hypointensity on T1-weighted images and hyperintensity on T2-weighted images, without specificity. Histological examination of the lesion removed by anterior orbitotomy confirmed the diagnosis of the SFT of the orbit. The patient was doing well without recurrence after 9 months.

DISCUSSION

The diagnosis of SFT is histological. It is a mesenchymal tumor. Immunohistochemically, the tumor cells are strongly positive for CD34 and vimentin.

CONCLUSION

The SFT of the orbit is a very rare and generally benign tumor. It must be immunohistochemically differentiated from other spindle-cell tumors of the orbit. The treatment is a complete surgical excision, and long-term follow-up is necessary because recurrence may appear long after treatment.

Nasal solitary fibrous tumor arising from the anterior cranial fossa

The solitary fibrous tumor (SFT) is a mesenchymal, spindle cell neoplasm that was originally found in pleural tissue. Recently, however, numerous extrapleural sites have been discovered, including the nasal cavity. We present the 15th case of a nasal SFT, and the first such tumor to arise from the cribriform plate and extend into the anterior cranial fossa. In addition to highlighting the aggressive nature of this tumor, we review its clinical features and the diagnostic difficulties posed by SFT.

Ultrastructural spectrum of solitary fibrous tumor: a unique perivascular tumor with alternative lines of differentiation

Eight tumors diagnosed as solitary fibrous tumor (SFT) of the oral cavity were studied. Histologic spectrum was entirely comparable with the extrapleural SFT of other sites. One tumor had glomus tumor-like foci. Immunohistochemical results confirmed most of the previous observations, indicating characteristic expression of vimentin, CD34, bcl-2, and CD99. Factor XIIIa and alpha-smooth muscle actin were less commonly reactive and a very few cells were faintly positive for factor VIII-related antigen and Ulex europaeus agglutinin 1. All were essentially negative for S-100 protein, desmin, CD31, and CD68. In stark contrast to the conclusive immunoprofile, ultrastructural investigation of six tumors demonstrated considerable cellular heterogeneity. Other than fibroblasts, perivascular undifferentiated cells and pericytes predominated, but endothelial cells were regularly present. There was a distinctive proliferation of pericytic cells in four tumors, one of which had glomoid foci of myopericytes. The extreme increase in number of Weibel-Palade bodies occurred in voluminous capillary endothelium. Occasional single and clustered cells with consistent features of endothelium showed intracytoplasmic lumen formation. Such composite cells constituted an integral segment of richly vascularized SFT. Myofibroblastic form smooth muscle differentiation was present in only a minority of cells. From phenotypic analysis by electron microscopy, SFT may originate from a unique, perivascular multipotent mesenchyme sharing with its lineage with pericytes, fibroblasts, and infrequently, endothelium. Consequently, morphological features of SFT may become diversely varied by whether predominantly constituent cells are undifferentiated, pericytic or fibroblastic in nature.

Solitary fibrous tumor of the orbit--two cases and a review of the literature

Solitary fibrous tumors of the orbit (SFT) are mesenchymal lesions that can develop either as malignant or benign neoplasias. We describe the histological features leading to the diagnosis in two females and review the current literature. Diagnosis of SFT only can be performed by histological examination, since clinical signs and radiological features are not specific enough. Even a malignant or benign course cannot be predicted, since clinical and radiological features do not correlate with histological signs of malignancy and vice versa. Radical resection is the treatment of choice, since no other treatment option has been proven to be efficient.

Solitary fibrous tumor of the orbit: a clinicopathologic study of six cases with review of the literature

Solitary fibrous tumor of the orbit is a rare spindle cell neoplasm. There are 42 cases of solitary fibrous tumor of the orbit available in the literature. We present six more cases of orbital solitary fibrous tumors, which presented to our institute between 1999 and 2001. We highlight the need for clinical recognition of these tumors as a distinct entity and inclusion of this tumor in the etiological differential diagnosis of well-circumscribed orbital lesions presenting as unilateral proptosis in both children and in adults. The diagnosis may be suspected based on radiological features supported by histopathologic and immunohistochemical study. The strong CD34 immunoreactivity of this tumor supports its diagnosis. Complete surgical resection is the most important prognostic factor of this tumor.

Solitary fibrous tumor of the orbit: is it rare? Report of a case series and review of the literature

PURPOSE

The real incidence of solitary fibrous tumor (SFT) of the orbit is unknown, but it seems that since it was first described in 1994, orbital SFT has been increasingly recognized. We believe that the orbital SFT is a relatively common tumor and that it should be considered in the differential diagnosis of any orbital tumor.

DESIGN

Interventional case series.

PARTICIPANTS

Four new cases of orbital SFT.

METHODS

Four patients affected by solitary fibrous tumor of the orbit are described. One patient experienced a recurrent SFT shortly after initial surgical excision performed elsewhere. Thirty-eight cases have been reported in the literature in 7 years.

RESULTS

The number of orbital SFTs reported has been increasing, reaching an average of more than five tumors reported per year. Since the first orbital SFT was described in 1994, 37 cases have been reported in the literature. We add four new cases in our series, including a recurrent tumor. A total of 42 cases have now been described, eight with recurrences. Malignant transformation occurred in one case.

CONCLUSIONS

We believe that before 1994, the diagnosis orbital SFT was confused with other benign orbital tumors, such as fibrous histiocytoma and hemangiopericytoma because of a lack of use of immunohistochemical techniques. This entity should now be considered relatively common and should be included in the differential diagnosis of orbital tumors in any age group. Local recurrences of SFT are possible and usually follow an incomplete initial excision. Recurrent tumors in the orbit have shown the tendency to infiltrate the surrounding tissues and the bone, rendering complete secondary excision more difficult. Recurrent orbital SFT also has the potential for malignant transformation. The treatment of choice of orbital SFT is complete surgical excision and careful follow-up. Considering the more aggressive course followed by recurrent tumor, correct diagnosis and management is essential.

Sinonasal-type hemangiopericytoma: a clinicopathologic and immunophenotypic analysis of 104 cases showing perivascular myoid differentiation

Sinonasal-type hemangiopericytoma is an uncommon upper aerodigestive tract tumor of uncertain cellular differentiation. We report 104 cases of sinonasal-type hemangiopericytoma diagnosed between 1970 and 1995 from the files of the Armed Forces Institute of Pathology. There were 57 females and 47 males ranging in age from 5 to 86 years (mean 62.6 years). The most common clinical presentation was airway obstruction (n = 57) and/or epistaxis (n = 54), with symptoms averaging 10 months in duration. The tumors involved the nasal cavity alone (n = 47) or also a paranasal sinus (n = 26), were polypoid, and measured an average of 3.1 cm. Histologically, the tumors were submucosal and unencapsulated and showed a diffuse growth with fascicular (n = 37) to solid (n = 50) to focally whorled (n = 7) patterns. The tumor cells were uniform in appearance with minimal pleomorphism and had spindle-shaped (n = 82) to round/oval (n = 18) nuclei with vesicular to hyperchromatic chromatin and eosinophilic to amphophilic to clear-appearing cytoplasm with indistinct cell borders. Multinucleated (tumor) giant cells were identified in a minority of cases (n = 5). Mitotic figures were inconspicuous and necrosis was absent. The tumors were richly vascularized, including staghorn-appearing vessels that characteristically had prominent perivascular hyalinization (n = 92). An associated inflammatory cell infiltrate that included mast cells and eosinophils was noted in the majority of cases (n = 87). The immunohistochemical profile included reactivity with vimentin (98%), smooth muscle actin (92%), muscle specific actin (77%), factor XIIIa (78%), and laminin (52%). Surgery was the treatment of choice for all of the patients; adjunctive radiotherapy was given to four patients. Recurrences developed in 18 patients within 1-12 years from diagnosis. Ninety-seven patients were either alive (n = 51, mean 16.5 years) or dead (n = 46, mean 9.6 years) but free of disease. Four patients had disease at the last follow-up: three died with disease (mean 3.6 years) and one patient is alive with disease (28.3 years). Recurrent tumor (17.8%) can be managed by additional surgery. The majority of sinonasal-type hemangiopericytomas behave in a benign manner with excellent long-term prognosis (88% raw 5-year survival) following surgery alone. Sinonasal-type hemangiopericytomas have a characteristic light microscopic appearance with an immunophenotypic profile resembling that of glomus tumors.

Solitary fibrous tumour of the nasal cavity and paranasal sinuses

OBJECTIVE

Solitary fibrous tumour (SFT) is an uncommon unilateral benign lesion that usually arises from the pleura. Recently, SFT has been described in many other locations, such as the mediastinum, head and neck, orbit and urogenital system. To date, only 21 cases of SFT arising from the nasal cavity and paranasal sinuses have been reported in the literature.

MATERIAL AND METHODS

We describe a case of SFT localized in the right nasal cavity with extension to the right ethmoid and sphenoid sinuses in a 43-year-old man who presented with a 6-month history of unilateral right-sided nasal obstruction, rhinorrhoea and recurrent epistaxis.

RESULTS

CT showed a large mass arising from the right anterior ethmoid and sphenoid sinuses. Histopathologically, the lesion consisted of a non-encapsulated mass with spindle-shaped cells within a collagenous stroma. Definitive diagnosis was obtained by means of immunohistochemical analysis, which showed vimentin and CD34 cells.

CONCLUSION

The tumour was removed by endoscopic sinus surgery, and the patient remained free of tumour after 12 months of follow-up.

Immunohistochemical comparison of gastrointestinal stromal tumor and solitary fibrous tumor

CONTEXT

The differential diagnosis of gastrointestinal stromal tumors (GIST) and solitary fibrous tumors (SFT) may be a diagnostic challenging because of overlapping clinicopathologic features. Many studies have shown consistent immunoreactivity for CD117 (c-Kit) in GIST. However, only a few studies have evaluated CD117 expression in SFT, and these studies have used an antibody from Santa Cruz Biotechnology. In non-GIST lesions, reactivity with this antibody has been shown to differ from that with a CD117 antibody from Dako Corporation. The immunoreactivity of SFT with the Dako CD117 antibody has not been reported. Conversely, CD99 is a marker for SFT, and its expression in GIST has not been evaluated.

OBJECTIVE

To study the immunohistochemical profiles of GIST and SFT to evaluate their diagnostic overlap.

DESIGN

We studied the immunoreactivity of 27 unequivocal GIST and 19 unequivocal extra-abdominal SFT for CD117, CD34, CD99, alpha-smooth muscle actin, vimentin, CD31, S100 protein, and muscle-specific actin. All antibodies, including CD117, were from Dako Corporation.

RESULTS

We found positive immunoreactivity for CD117 in 100% of GIST and none of SFT; for CD34 in 89% of GIST, and 100% of SFT; for CD99 in 89% of GIST and 100% of SFT; for alpha-smooth muscle actin in 48% of GIST and 31% of SFT; for vimentin in 89% of GIST and 90% of SFT; and for muscle-specific actin in 22% of GIST and none of SFT. None of the GIST or SFT showed immunoreactivity for CD31 and S100 protein.

CONCLUSIONS

The major difference between GIST and SFT was strong CD117 immunoexpression in all GIST and an absence of this expression in all SFT. With the exception of muscle-specific actin, the prevalence of immunoreactivity for the markers studied did not differ substantially between these 2 tumors. We conclude that GIST and SFT show distinctly divergent immunoprofiles with respect to CD117 and muscle-specific actin.

Solitary fibrous tumor of the orbit

Painless unilateral proptosis is a frequent manifestation of numerous orbital neoplastic and non-neoplastic processes. Various mesenchymal tumors of both fibrohistiocytic and vascular origin are well-described causes. Solitary fibrous tumors (SFTs) are rare spindle-cell neoplasms usually found associated with serosal surfaces, especially the pleura, but they have recently been described in a number of extrapleural sites including the orbit. The authors describe the case of an 18-year-old man who presented with a 6-month history of painless proptosis in the right eye. A visible nontender mass in the right supermedial orbit producing ptosis of the upper lid was present. Magnetic resonance imaging (MRI) showed a well-circumscribed soft tissue mass located above the right globe with no obvious invasion of adjacent orbital structures. Uneventful surgical excision through a right frontal-orbitotomy approach was performed. Histological evaluation showed a solid, highly vascular tumor mass composed of spindle cells arranged in short ill-defined fascicles. Intense immunohistochemistry staining for CD34 and B-cell lymphoma 2 (BCL-2) differentiated the lesion from the more common hemangiopericytoma. Though considered benign, local recurrence and extraorbital extension of orbital SFTs have been described. Malignant behavior, including distant metastases, has been documented in as many as 20% of pleural cases with mortality rates as high as 50%. The natural history of this tumor in the orbit is unclear. The authors report the 35th case of orbital solitary fibrous tumor and discuss the differential diagnosis, histopathology, radiological features, and clinical course.

Solitary fibrous tumor of the abdominal wall: a report of two cases immunohistochemical, flow cytometric, and ultrastructural studies and literature review

Solitary fibrous tumors have been described at many extrapleural sites in recent years. However, solitary fibrous tumors arising from somatic soft tissue occur only rarely and can pose problems in the differential diagnosis from other benign or malignant soft tissue tumors. The majority of solitary fibrous tumors occurring in the somatic soft tissue have been found in the extremities and limb girdles, and the head and neck regions. There have been only eight published cases located in the abdominal wall. We herein report two female patients who developed solitary fibrous tumors of the abdominal wall that were not in association with the underlying peritoneum. Histologically, both tumors were characterized by a variety of architectural patterns, alternating hypercellular and hypocellular areas, proliferation of plump spindle cells, thick keloid-like and/or amianthoid collagen bundles, and ectatic staghorn-like vessels. Both tumors showed a diffuse strong reaction for CD34 and vimentin as well as focal positivity for bcl-2 and smooth muscle actin. A striking predominance in females was found in a literature review of solitary fibrous tumors of the abdominal wall, contrasting with other somatic soft tissue sites which show an equal gender distribution. Interestingly, expression of estrogen but not progesterone receptor was observed in both tumors. Ultrastructurally, the tumor cells displayed features of fibroblasts with dilated branching rough endoplasmic reticulum (RER) and Golgi apparatus. Both tumors assayed by flow cytometry demonstrated a diploid DNA content with an S-phase fraction of 7.9% and 11.4%, respectively. At follow up, both patients were well without evidence of recurrence or metastasis after surgical excision.

Solitary fibrous tumor of the orbit with extraorbital extension: case report

OBJECTIVE AND IMPORTANCE

Solitary fibrous tumors (SFTs) are rare tumors of mesenchymal origin that typically arise in the pleura. Only 24 cases of SFTs in the orbit have been reported, all located within the orbit and generally with a benign course. We report the first case of an orbital SFT with extraorbital extension and short-term regrowth.

CLINICAL PRESENTATION

A 54-year-old man presented with proptosis and double vision that had persisted for 7 months. The tumor extended from the right extraconal inferolateral orbit to the extradural middle cranial fossa and cavernous sinus, via the superior orbital fissure, on magnetic resonance imaging scans. Positron emission tomography with [(18)F]fluorodeoxyglucose demonstrated faint uptake in the orbital portion.

INTERVENTION

Resection of the tumor was performed twice, because of short-term regrowth of the residual tumor in the orbit. The histological diagnosis was a SFT. The MIB-1 labeling index was 7% and the mitotic count was 5 mitotic figures/10 high-power fields at the time of the second operation. These findings indicate the malignant nature of the tumor.

CONCLUSION

The natural history of SFTs of the orbit remains unclear, and the importance of careful and continued follow-up monitoring of the tumor should be emphasized.

Solitary fibrous tumor of the orbit. Case report and review of the literature

BACKGROUND

Solitary fibrous tumor (SFT), which usually presents in the pleura and is thought to be mesothelial in nature, has been recently discovered in extrapleural sites, including the orbit. Presently ultrastructural studies show absence of epithelial-mesothelial features, and reactivity of the tumor cells to CD34 antigen on immunohistochemical analysis suggests the mesenchymal origin of such tumors.

CASE DESCRIPTION

A 40-year-old woman had a 4-year history of progressive swelling of her right upper lid and a slow-growing palpable mass of the orbit. CT and MR imaging showed a well circumscribed, nonenhanced extraconal mass with mild erosion of the right orbital roof. The tumor was totally excised. Histological examination disclosed a spindle-cell tumor in a dense fibrous tissue. Immunohistochemistry showed positive staining for vimentin and CD34. We review the clinical, diagnostic, and surgical features of 22 orbital SFTs including the present case.

CONCLUSIONS

Orbital SFT generally pursues a slow, indolent, and nonaggressive course, reaches a size up to 4.5 cm, and can be cured by a single excision. It must be immunohistochemically differentiated from other spindle-cell tumors of the orbit.

Orbital hemangiopericytoma and solitary fibrous tumor: a morphologic continuum

Solitary fibrous tumors (SFT) and hemangiopericytomas (HPC) are soft tissue tumors with known histologic and immunohistochemical overlap. A series of these tumors located in the orbit were analyzed in order to determine whether they could be re-classified based on currently recognized histologic criteria. Ten orbital spindle cell lesions, all of which were positive for CD34 antigen, were examined. Diagnostic criteria for SFT included a cytologically bland spindle cell lesion with variable cellularity and focal dense collagenization with diffuse, strong CD34 reactivity, while the criteria for HPC required a more monotonous cellular proliferation without significant variability in cellularity, a "staghorn" vascular pattern, minimal collagenization, and focal or absent CD34 staining. Tumors with typical histologic and immunohistochemical features of HPC or SFT were diagnosed as HPC and SFT, respectively. Those tumors with histologic or antigenic profiles not classic for HPC or SFT were defined as 'indeterminate.' Three lesions were classified as SFT and 1 tumor was diagnosed as HPC through use of the above-cited histologic criteria. All lesions showed positive staining of tumor cells with CD34 antigen in varying amounts and were negative for cytokeratin AE1-3, epithelial membrane antigen, CD68, and Factor XIIIa. One solitary fibrous tumor focally stained for S-100 protein and 1 hemangiopericytoma was focally positive for HHF-35. Of the 10 analyzed tumors, 6 were classified as 'indeterminate.' Furthermore, 1 lesion whose primary histology was that of an SFT recurred 9 years later with an appearance consistent with an 'indeterminate' lesion. Our results call into question the present histologic separation of HPC and SFT in the orbit. As in other sites, including deep soft tissue, these data suggest that SFT and HPC are 2 lesions whose morphologic features are best interpreted to exist along a continuum, rather than 2 lesions with distinctly defined histopathology.

Solitary fibrous tumor of the orbit in a child

PURPOSE

Solitary fibrous tumor is a rare spindle-cell tumor that usually is seen in the pleura. The orbit is one of the most common extrapleural sites. It is frequently misdiagnosed as hemangiopericytoma and is seen in older patients. We present the youngest case of this tumor, which was apparent in family photographs by age 10 and removed at age 15. The first reported echography findings are presented.

METHODS

Case report and literature review.

RESULTS

Solitary fibrous tumor was diagnosed by microscopy and immunohistochemical study that showed cells reactive with vimentin and CD34.

CONCLUSIONS

Solitary fibrous tumor of the orbit has been diagnosed with increasing frequency in recent years as the result of improved methods of pathologic examination. It is important to be aware of this tumor and recognize that it must be included in the differential diagnosis of highly vascular spindle-cell tumors even in young children.

Aggressive CD34-positive fibrous scalp lesion of childhood: extrapulmonary solitary fibrous tumor

Although solitary fibrous tumor (SFT) was originally described as a pleural tumor, an increasing number of extrapleural sites of SFTs have been documented. This has been attributed not only to the heightened awareness of the spectrum of histopathological features that characterizes SFTs but also to the recognition of the role of CD34 immunostaining in soft tissue tumors in general, and in SFTs in particular. Despite the large number of documented extrapleural SFTs in adults, cranial SFTs are rare, having been documented in the meninges, scalp, and infratemporal fossa. Extrapleural SFTs are, to date, an unrecognized entity in children. We document an aggressive fibrous scalp lesion in a 30-month-old female child that demonstrated features common to benign cranial fasciitis and SFT. However, based on bright, diffuse CD34 antigen immunopositivity, a diagnosis of SFT was made. The need to include the CD34 antigen stain in a panel of immunohistochemical markers used to assess spindle cell lesions of childhood is emphasized.

Orbital solitary fibrous tumor: radiographic and histopathologic correlations

OBJECTIVE

To correlate the clinicopathologic and radiographic features characteristic of orbital solitary fibrous tumor (SFT).

METHODS

The diagnostic features and clinical outcome of seven adults with orbital SFT are retrospectively outlined. Orbital imaging was performed by ultrasonography, computed tomography, or magnetic resonance imaging. Some cases were imaged by multiple modalities. Histopathologic examination of each tumor specimen included standard light and immunohistochemical stains.

RESULTS

Heterogeneous internal composition was better appreciated on magnetic resonance imaging than on computed tomography. All cases undergoing magnetic resonance imaging showed T1 isointensity and T2 hypointensity relative to gray matter. Strong, generalized immunohistochemical reactivity to vimentin and CD34 validated the diagnosis of SFT and differentiated the specimens from other spindle cell neoplasms. After complete tumor resection, our patients remain tumor free with postoperative intervals of 15 to 45 months.

CONCLUSIONS

Solitary fibrous tumor has now been reported in 26 orbits. No physical finding is pathognomonic, but several imaging traits are highly characteristic. Intralesional image heterogeneity and a predominantly low T2 signal intensity are distinctive of SFT. Complete tumor resection and immunohistologic specimen evaluation are emphasized. Clinicians should consider the diagnosis of SFT when confronted with an adult patient having an orbital soft tissue mass demonstrating the distinctive magnetic resonance imaging findings.

Solitary fibrous tumour of the orbit. Report of a new case

PURPOSE

Solitary fibrous tumour (SFT) of the orbit is a very rare lesion that may be misdiagnosed as fibrous histiocytoma, haemangiopericytoma, or other orbital tumour. We studied a case of SFT of the orbit in a 35-year-old woman.

METHODS

The patient, with a 1-year history, reported a 'pressure' sensation behind her right eye, but no pain, vision changes, or other associated symptoms. Ocular examination was normal. Magnetic resonance imaging (MRI) showed a well-circumscribed medial mass in the right orbit. The tumour was excised.

RESULTS

The tumour was a cellular spindle-cell neoplasm with a storiform pattern. The tumour cells were spindle-shaped with bland nuclei and rare mitoses. Immunostaining was positive for vimentin and CD34, but negative for cytokeratin (AE1-AE3), EMA, desmin, smooth muscle actin, S-100, CD31, CD45 and bcl-2.

CONCLUSION

SFT can infrequently involve the orbit. The tumour must be removed entirely to avoid recurrences. Careful and continued follow-up is important because orbital recurrence may occur several years after the excision of the primary tumour.

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.

Giant cell angiofibroma of the orbit and eyelid

PURPOSE

To report the clinicopathologic features of a newly recognized tumor, giant cell angiofibroma.

DESIGN

Observational case series.

MAIN OUTCOME MEASURES

Clinical and histopathologic features of giant cell angiofibroma.

METHODS

Light and electron microscopy and immunohistochemistry of five cases of giant cell angiofibroma.

RESULTS

A total of five patients (4 women and 1 man) are described: two presented with a painless mass in the eyelid, two with a mass in the orbit, and one presented with a conjunctival lesion. All lesions were well demarcated with no capsule and were composed of blood vessels, a patternless spindle-shaped cell proliferation with a solid and pseudovascular appearance, and multinucleated giant cells. Both spindle-shaped and giant tumor cells were intensely positive for CD34 and vimentin.

CONCLUSION

Giant cell angiofibroma resembles solitary fibrous tumor and giant cell fibroblastoma and should be considered in the differential diagnosis of spindle-cell tumors in the eyelid, orbit, and conjunctiva.

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.

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.

Hypoglycaemia associated with a solitary fibrous tumour of the pleura

We report the interesting case of an elderly woman who presented with hypoglycaemic episodes and weight loss. She was found to have a solitary fibrous tumour weighing more than 1.7 kg arising from the diaphragmatic pleura, which had been producing insulin-like growth factor II. After surgical removal of this well-encapsulated, pedunculated tumour her hypoglycaemia resolved and she returned to normal both clinically and biochemically.

Atypical and malignant solitary fibrous tumors in extrathoracic locations: evidence of their comparability to intra-thoracic tumors

Solitary fibrous tumor (SFT), first described as a pleural lesion, has been reported at numerous extrathoracic sites over the past 10 years. About 10% to 15% of intrathoracic SFTs are histologically or clinically malignant, but such cases have very rarely been described at other locations. Among 92 cases of extrathoracic SFT in our files, we identified 10 that either had recurred (2 cases) or had a least one atypical histologic feature (8 cases). The ten tumors occurred in five men and five women, 32 to 81 years old (median 56), measured 1.9 cm to 20 cm (median 11.5 cm), and were located in the abdomen/pelvis (4 cases), retroperitoneum (3 cases), groin, trunk, and upper arm. Nuclear atypia (8 cases), markedly increased cellularity (6 cases), areas of necrosis (4 cases), and greater than 4 mitoses/10 HPFs (3 cases) were seen in addition to the typical histologic features of SFT. Six tumors had at least two of these atypical histologic features. Nine cases were positive for CD34, six were positive for O-13, and one was focally positive for smooth muscle actin. Eight were excised completely. Subsequent follow-up revealed tumor relapse in eight cases (follow up 6-180 months, median 24). Four patients had local recurrence at 12 to 168 months. Distant metastasis developed at 1 to 6 years in five cases with spread to lung (2 cases), liver (4 cases), and bone. Metastasis or local recurrence developed within 2 years in five patients. To date, no patient has died of their tumor. These findings demonstrate that nuclear atypia, hypercellularity, greater than 4 mitoses/10 HPFs, and necrosis may be seen in up to 10% of extrathoracic SFTs, and are associated with, but are not by themselves predictive of, aggressive clinical behavior. In addition, our findings confirm that the behavior of extrathoracic SFTs is unpredictable, entirely comparable to that of their better known pleural counterparts, and confirm that patients with SFTs in all locations require careful, long-term follow up. It is probably unwise to regard any such lesion as definitely benign.

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.

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.

Pleomorphic hyalinizing angiectatic tumor of soft parts

A case of recently described pleomorphic hyalinizing angiectatic tumor (PHAT) of soft parts is reported. The subcutaneous solid tumor arising in the axilla of a 58-year-old man was histologically characterized by sheets of mitotically inactive oval and pleomorphic cells, intranuclear cytoplasmic inclusions, and clusters of ectatic vessels with perivascular hyalinization. Mono- and multinucleated giant cells were also present. A hemangiopericytoma-like pattern of vascularity, pseudovascular spaces, stromal collagen with degenerative changes, and immunoreactivity for CD34 were observed. Since these features were very similar to those of solitary fibrous tumors of various sites and newly categorized giant cell angiofibroma, it is considered that PHAT, solitary fibrous tumor, and giant cell angiofibroma may be in the same family of tumor. The tumor was diploid with a low S-phase fraction. The patient was well with no evidence of disease for 23 months.