Solitary fibrous tumors of soft tissue. A clinicopathologic and immunohistochemical study of 12 cases

Thoracic solitary fibrous tumors with small cell features: A clinicopathological and immunohistochemical analysis of 5 cases

Five cases of thoracic solitary fibrous tumor (SFT) with small cell features are presented mimicking a neuroendocrine neoplasm. The patients were four men and one woman aged 43 to 74 years who presented with symptoms of chest pain, cough, dyspnea or hemoptysis. Two tumors were intrapulmonary neoplasms, while three were pleural-based. Grossly, the tumors ranged in size from 4 to 6 cm and were white and solid; in two tumors necrosis was apparent. Histologically, they were characterized by a cellular proliferation composed of small cells with round nuclei and inconspicuous nucleoli. The cellular proliferation in some areas had a subtle nested pattern, while in other areas the tumor showed extensive sclerosis and small vessel proliferation. Cellular pleomorphism was not marked and the mitotic activity varied from 1 to 5 mitotic figures per 10 high power fields. Microscopically, necrosis was observed in two cases and focally present in one. Immunohistochemical stains showed tumors cells universally negative for pancytokeratin; in the two pulmonary cases, focal staining for synaptophysin, CD56, and INSM1 was observed. The unexpected lack of expression of pancytokeratin led to additional analysis revealing positive staining with CD34 and STAT6 confirming a diagnosis of SFT. Clinical follow-up showed tumor recurrence in one patient while three patients remained alive and well after a period of 12 to 20 months. The current cases highlight an unusual variant of SFT that may be confused with other small cell tumor entities, such as neuroendocrine or neuroectodermal tumors, especially when originating in the thoracic cavity.

Diagnostics and Treatment of Extrameningeal Solitary Fibrous Tumors

Solitary fibrous tumors (SFT) are rare mesenchymal neoplasms that account for less than 2% of all soft tissue masses. In the latest WHO 2020 Classification of Soft Tissue Tumors, extrameningeal SFT was listed as intermediate (rarely metastasizing) or malignant neoplasms. Due to the lack of characteristic clinical features, their diagnosis and treatment remain challenging. The pathogenesis of SFT is often associated with the presence of fusions of the NAB2-STAT6 gene on the 12q13 chromosome. Cytoplasmic CD34 positive staining is considerably characteristic for most SFTs; less frequently, factor XII, vimentin, bcl-2, and CD99 are present. A key factor in the diagnosis is the prevalent nuclear location of STAT6 expression. Radical resection is the mainstay of localized SFTs. In the case of unresectable disease, only radiotherapy or radio-chemotherapy may significantly ensure long-term local control of primary and metastatic lesions. To date, no practical guidelines have been published for the treatment of advanced or metastatic disease. Classical anthracycline-based chemotherapy is applicable. The latest studies suggest that antiangiogenic therapies should be considered after first-line treatment. Other drugs, such as imatinib, figitumumab, axitinib, and eribulin, are also being tested. Definitive radiotherapy appears to be a promising therapeutic modality. Since standards for the treatment of advanced and metastatic diseases are not available, further investigation of novel agents is necessary.

An extremely rare case of an isolated primary benign pelvic Solitary Fibrous Tumor in an elderly female

INTRODUCTION AND IMPORTANCE

Solitary Fibrous Tumors are highly rare spindle cell tumors of mesenchymal origin. They comprise <2 % of all types of soft tissue tumors and are characterized by an age-adjusted annual incidence rate of 0.61 per 1 million individuals for extra-meningeal Solitary Fibrous Tumors. The disease course is mostly asymptomatic but can still present with non-specific symptoms. This results in misdiagnosis and delayed treatment. In turn, morbidity and mortality rises and it will constitute a clinical and surgical burden for the affected patients.

CASE PRESENTATION

We present the case of a 67-year-old female who has a known history of controlled hypertension, who presented to our hospital complaining of non-specific pain in her right flank and lower lumbar region. Our preoperative diagnostic radiological workup demonstrated an isolated antero-sacral mass.

CLINICAL DISCUSSION

Comprehensive excision of the mass was laparoscopically achieved. Following the necessary analysis via histopathology and immunohistochemistry, we definitively established the diagnosis of an isolated primary benign Solitary Fibrous Tumor.

CONCLUSION

To the best of our knowledge, no previous cases of SFTs from our country were documented. Clinical suspicion and complete surgical resection are vital determinants in treatment of such patients. Further research and documentation are warranted to set-up the necessary guidelines for preoperative assessment, intraoperative techniques, and adequate follow-up protocols to limit the ensuing morbidity and to detect any possible neoplastic recurrence.

Epithelioid and Clear Cell Solitary Fibrous Tumors: Clinicopathologic, Immunohistochemical, and Molecular Genetic Study of 13 Cases

Solitary fibrous tumors (SFTs) are ubiquitous soft tissue neoplasms known for their protean histology and potentially aggressive behavior. Although most cases are composed of a monotonous proliferation of spindle cells, some tumors show unusual cytologic features. We have studied 13 SFTs that were characterized by a predominant population of round epithelioid cells with abundant eosinophilic cytoplasm and clear cell changes. The tumors occurred in 8 women and 5 men, aged 36 to 80 years (mean=63 y), and were located within the orbit (3), lower extremity (3), retroperitoneum (2), abdominal cavity (2), and superficial soft tissues of the neck, pelvis, and pubis (1 each). The tumors measured from 3.5 to 24.5 cm. Using a risk assessment system, 6 cases were stratified as low-risk tumors; 3 of these showed no evidence of recurrence or metastases from 6 to 18 years, and 1 tumor in the orbit recurred and led to the patient's demise. Five cases were of intermediate risk; clinical follow-up showed no evidence of recurrence or metastases from 3 to 4 years in 3 patients, and 1 patient suffered a recurrence 4 years after diagnosis. Two cases were high risk; 1 patient died after 1 year and the second patient experienced local recurrence at 4 years. Immunohistochemical studies showed nuclear positivity for STAT6 in 10 cases. CD34 immunohistochemistry was positive in 11 cases. A NAB2::STAT6 rearrangement was present in all cases. Epithelioid and clear cell SFT should be considered in the differential diagnosis of soft tissue neoplasms with epithelioid and clear cell morphology.

Orbital solitary fibrous tumours: clinicopathological characteristics and recurrence prediction

BACKGROUND

SFTs are thought to have an unpredictable clinical course and currently have no recognized prognostic criterion. Our study aimed to determine the relationship between clinicopathological characteristics and the prognosis of patients with orbital SFTs.

METHODS

The clinicopathological features of these patients were extracted from clinical records. The relationships between these features and prognosis were analysed.

RESULTS

The positive rates of CD34, CD99, Blc2, and STAT6 expression were 90.3%, 90.3%, 83.9%, and 100%, respectively. The tumour recurrence rate was 38.7%. A higher recurrence rate was observed in patients with Ki67 index ≥ 5 (56.25% vs. 20%, P = 0.038).

CONCLUSION

A Ki67 index ≥ 5 was an effective parameter for predicting tumour recurrence of orbital SFTs. Close follow-up is needed for these patients.

Solitary Extrapleural Fibrous Tumor in Salivary Glands: Our Experience-Case Series and Literature Review

(1) Background: Extrapleural solitary fibrous tumors (ESFTs) are rare oncological entities occurring in the head and neck, and even more so in the salivary glands. The clinical presentation and histologic features are usually unspecific, resulting in frequent misclassification. As an unusual tumor, ESTFs have an unpredictable clinical behavior. (2) Methods: We present two clinical cases referred to our Maxillofacial Surgery Unit for the onset of a symptomless mass involving, in one case, the parotid gland, and in the other case, the sublingual gland. (3) Results: Solitary fibrous tumors could be considered as neoplasms with intermediate biological behavior that are not entirely predictable on the basis of morphological features, as these are mostly still unknown. However, a few histologic, immunohistochemical, and imaging features, such as a hypodense signal at the T1 sequence in an MRI, or positivity for CD34, bcl2, and CD99, and the NAB2-STATS6 fusion gene, could be useful for an early differential diagnosis of ESTFs. (4) Conclusions: All patients were alive at follow-up with no evidence of disease. Surgical management should always be considered as the first choice for oncological radicality, and clinical behavior should always be defined with the help of the study of radiological and anatomopathological features.

Surgical excision of giant vulvar angiofibroma: A case report and a review of literature

RATIONALE

Cellular angiofibroma (CA) is a rare tumor of the soft tissue classified as a benign fibroblastic/myofibroblastic tumor. Considering this, the literature regarding CA mainly, but not exclusively, comprises single case reports and case series. Here, we report a case of giant CA of the vulva with comprehensive literature review.

PATIENT CONCERNS

We present a case of a massive vulvar CA arising in 53-year-old woman with no notable medical or surgical history. The mass has grown considerably over time, causing pain and difficult urination, defecation, and movement. The patient had normal regular menstrual cycle with no previous contraception use. Vaginal examination exposed a right-sided large tender vulvar mass with normal-looking vagina.

DIAGNOSES

Pelvic magnetic resonance imaging with contrast revealed a large right vulvar heterogeneously enhancing soft tissue mass measuring 13.1 × 10.9 × 10.7 cm expending the left vulva, with internal and peripheral voids resembling feeding vessels. The mass was surgically removed, and subsequent histopathology showed skin-covered dermal-based lesion composed of fibroblast-like bland and spindle cell proliferation with thin-walled blood vessels of various sizes. Immunohistostaining of CD34 and smooth muscle antigen were both positive, while desmin was found to be negative. A diagnosis of vulvar angiofibroma was made based on the clinical scenario, imaging, and histopathology.

INTERVENTIONS

Mass vulvectomy was performed starting with a circumferential incision at the base of the mass and structural dissection to separate the mass from the vulvar wall. The incision was successfully closed, and subcuticular stitches were applied to the skin.

OUTCOMES

The patient's complaints were significantly relieved with no postoperative complications and the patient is being followed regularly in an outpatient setting.

LESSONS

Due to its extremely benign nature of CA, and the implausible ability of its recurrence, it was decided to surgically excise it. Despite its rarity, it can be readily identified at its earlier stages preventing the vexing and exasperating symptoms accompanied with increased size as mentioned.

Cutaneous solitary fibrous tumor: Report of three cases with review of histopathological mimics

Solitary fibrous tumor (SFT) is a relatively uncommon spindle cell mesenchymal neoplasm that is most often based on the pleura but may rarely arise in extrapleural locations, including the skin. Herein, we describe three cases of cutaneous SFTs. SFT is characterized by epithelioid and spindle cells arranged in random patterns with focal prominent stromal collagen and pericytomatous vessels. Immunohistochemical evaluation is required for definitive distinction of SFT from other benign and malignant cutaneous spindle cell neoplasms. Although aggressive biologic behavior is uncommon, accurate diagnosis of it is required for prognostication and counseling. CD34, bcl-2, and CD99 stains are positive in SFT, but not specific. STAT6 is the most sensitive and specific immunohistochemical marker to confirm diagnosis of SFT.

Solitary fibrous tumor of thoracic cavity, extra-thoracic sites and central nervous system: Clinicopathologic features and association with local recurrence and metastasis

Published risk stratification models of solitary fibrous tumor (SFT) have been associated with distant metastases outside the central nervous system (CNS), but have not been studied for tumors occurring in the CNS. In a retrospective review, we identified 72 cases of solitary fibrous tumor or hemangiopericytoma (HPC) diagnosed between January 2011 and December 2020 at our institution. The tumors involved the central nervous system (N = 17), thoracic cavity (N = 28), and extrathoracic sites (N = 27). The risk of local recurrence, distant metastasis, or death at 5 years was 57% (95% CI 23%, 76%) in the CNS, 24% (95% CI 2%, 41%) in the thoracic cavity, and 13% (95% CI 0%, 25%) in extrathoracic sites. By contrast, the risk of distant metastasis or death at 5 years was 13% (95% CI 0%, 29%) in CNS primaries, 5% (95% CI 0%, 14%) in thoracic primaries, and 14% (95% CI 0%, 27%) in extrathoracic primaries. Using the published 3- and 4-variable risk stratification models by Demicco et al., we retrospectively assessed our cases for risk of local recurrence, distant metastasis, and death. For tumors outside the CNS, we show that three- and four-variable risk stratification models were associated with recurrence-free survival in addition to the previously known association with distant metastasis (all P < 0.05). In contrast, inside the CNS, we show that neither risk model is a significantly associated with clinical behavior, and that WHO grade is likely the best available prognostic tool, though none of the differences were significant. The lack of significant differences can be likely explained by the younger median age (47 years vs 61 years) and smaller median tumor size (3.5 cm vs 5.6 cm), downgrading the risk stratification scores in CNS compared to non-CNS primaries. In conclusion, existing risk stratification models of SFT are not associated with clinical behavior for tumors arising inside the CNS, but are associated with local recurrence in addition to distant metastasis outside the CNS.

Surgical resection of a presacral solitary fibrous tumor with extension to iliac vessels using Karakousis's abdominoinguinal approach: Report of a rare case

Introduction and importance

The solitary fibrous tumor (SFT) is a rare tumor of mesenchymal origin, with a reported incidence of 2.8 cases per 100,000 tumors and with distinctive histopathological and immunohistochemical characteristics. It was initially described as a pleural lesion and subsequently, it was found in different organs and tissues. The abdominoinguinal incision described by Karakousis allows a safe and radical approach for lower quadrants abdominopelvic tumors.

Case presentation

A 47-year-old man was referred to us with a 5-months history of lower backache radiating to the left lower limb. MRI and CT revealed a retroperitoneal mass of 10 cm extending to left iliac vessels. The initial diagnosis corresponded to a sarcomatous retroperitoneal tumor. It was decided to perform an abdominal exploration using Karakousis's approach for surgical resection. The immunohistochemistry and histopathological study revealed neoplasia compatible with a SFT. It was categorized as low risk for developing metastasis and death from disease, according to the new malignancy criteria. Currently, the patient is asymptomatic and disease-free at 19 months after surgery.

Clinical discussion

Most patients with SFTs present symptoms derived from the tumor growth and the compression on adjacent structures with clinical manifestations that are frequently insidious and precede the tumor discovery. The diagnosis is based on histopathological studies. Nonetheless, when they present an extrathoracic location, they represent a diagnostic challenge, due to their variable histological characteristics.

Conclusion

Presacral SFT is a rare entity, with a scant incidence reported regarding this location and long-term treatment. Surgical resection is needed as the immediate treatment.

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A solitary fibrous tumor (SFT) is a rare tumor of mesenchymal origin.

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SFT requires immediate treatment with surgical resection.

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The Karakousis abdominoinguinal incision allows a safe and radical approach.

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The presacral SFT with extension to iliac vessels benefits from the Karakouis approach.

Perianal Solitary Fibrous Tumor in a Rare Anatomical Presentation: A Case Report and Literature Review

BACKGROUND Solitary fibrous tumors (SFTs) account for <2% of all soft tissue tumors and are slow-growing neoplasms of mesenchymal origin, which have been reported in various locations. They are frequently observed at the pleura and a perianal location is extremely rare. They show no predisposition by sex, are mainly benign, and usually occur between the 5th and 7th decades of life. CASE REPORT We report the case of an 80-year-old man with no comorbidities except hypertension, who presented with an asymptomatic perineal mass. Magnetic resonance imaging showed a solid tumor measuring 3.5×2.5 cm identified in the perineal midline. It was very close to the anal sphincter, showing no extension to the rectum or anus. The tumor was completely excised with negative margins. The postoperative course was uneventful and he was discharged home, free of any symptoms. The pathological examination showed a benign completely excised SFT, and no further treatment was necessary. At the 6-month and 1-year follow-ups, there was no sign of recurrence. CONCLUSIONS A comprehensive review of all the reported cases of perianal SFTs shows that the majority of these tumors present with no symptoms and have a favorable prognosis. Diagnosis is possible only after a pathological examination. The criterion standard of treatment is complete excision with negative margins. Once excised, the tumors have low rates of recurrence and metastasis. Tumors very close to the anal sphincter and with malignant potential need to be operated on with extra care to obtain clear margins without disrupting the continence mechanism.

Oral Solitary Fibrous Tumor: A Retrospective Clinico-Pathological Study and Long-Term Follow-Up

Background and Objectives: This was a retrospective single-center study to analyze and describe the clinical and histological features of all cases of oral solitary fibrous tumor (SFT). Study design: the study included all consecutive cases of oral SFT diagnosed between 2008-2018 at a single tertiary center. Materials and Methods: Clinical data was retrieved from medical charts. The diagnosis of oral SFT was based upon the morphologic features of the lesions, in routine hematoxylin and eosin (H&E) stained sections and confirmed by immunohistochemical analyses including CD34, CD99, Bcl2, and stains for STAT6. Results: Seven cases of oral SFT were found. Of these, three (42%) were in males and four (58%) in females. The age range was 24-63 years (mean 47 ± 13). Four (58%) lesions were located in the buccal mucosa, two (28%) in the labial mucosa and one (14%) on the floor of the mouth. The diameter ranged between 3-50 mm (mean 22 ± 14 mm). All patients were treated with local excision. Follow-up periods were between 2-74 months (mean 41 ± 27). No recurrences were reported. Conclusions: We present a series of oral SFT, which were all non-aggressive in presentation and did not recur after conservative surgery (local excision) over a relatively long follow-up period.

Solitary Fibrous Tumor in the Perianal Region: Report of Two Cases With an Atypical Location

A solitary fibrous tumor (SFT) is a mesenchymal neoplasm of spindle cells, initially described in the pleura. The World Health Organization (WHO) classifies the solitary fibrous tumor as a neoplasm with intermediate biological potential. Diagnostic images are essential for the diagnostic and therapeutic approach in this entity. The standard of treatment for this type of lesion is surgical resection with oncological margins larger than 1 cm. The solitary fibrous tumors located in the perianal, perineal, and pelvic regions are infrequent and represent a challenge in the clinical approach, mainly because the manifestations are nonspecific. Given the low incidence of this type of neoplasm, we present two cases of SFT in the perianal region managed in a high-complexity hospital.

A Case of Solitary Fibrous Tumor of Subungual Region

Solitary fibrous tumor (SFT) is a relatively uncommon mesenchymal neoplasm that usually arises in the pleura, but also has been reported in numerous extrapleural locations, including cutaneous site. The skin lesion presents as a circumscribed nodule or tumor, mainly on the head and neck. A 41-year-old male presented with 6 months history of nail lesion without symptom on the left third finger. The lesion is slightly yellowish discoloration with subungual erythematous nodule and distal onycholysis. Biopsy specimen from the nail lesion showed the spindle cells form patternless pattern with hypercellular and hypocellular area. And small blood vessels and dilated vascular spaces were present. The result of special stain for specimen showed that positive for CD34, Bcl-2, and CD99 but negative for S-100, FactorXIIIa, and smooth muscle action. Recognition of this uncommon location of SFT is important because of possible confusion with other subungual tumors, including glomus tumor, fibroma and other fibrohistiocytic tumors like dermatofibrosarcoma protuberans, superficial acral fibromyxoma and cellular digital fibroma. Here in, we report a case of SFT of subungual region. We think this case is interesting because of uncommon location and may be helpful to more understand the character of this disease.

Cervical, Intradural Extramedullary Solitary Fibrous Tumor of the Spinal Cord: A Case Report and Review of the Literature

Solitary fibrous tumors (SFTs) are rare, spindle cell neoplasms of the mesenchymal origin. Lesions localized to the spine are exceptionally uncommon, only described in the literature in case reports and small case series. While these lesions are typically benign, there are a few reports in which they recur or present as malignancies. The patient presented in the case herein was a 72-year-old male, who presented with a 1-year history of lower extremity weakness, pain, and numbness and was found to have a cervical, intradural extramedullary tumor. In addition to the case report, the authors perform a thorough review of all previously published cases of spinal SFT.

Malignant solitary fibrous tumor in the subcutis: Report of a rare superficial malignant type and review of published work

An 82-year-old Japanese man presented with a 90 mm × 80 mm subcutaneous nodule on the left chest, not connected to the pleura, described as hypointense on T₁ -weighted magnetic resonance imaging. Histologically, a well-demarcated nodule demonstrated a patternless pattern composed of hemangiopericytoma-like and short storiform patterns from the subcutis into deeper tissue. Antler-like branching blood vessels and keloidal-type collagen bundles were seen. Myxoid change was seen in hypocellular areas. Bizarre cells and multinucleated giant cells could be easily identified. Approximately 5 mitoses per 10 high-power fields could be detected. The majority of proliferating spindle cells were positive for CD34, CD99 and BCL2 expression. Signal transducer and activator of transcription (STAT)6 was strongly expressed in the nuclei. The Ki-67 proliferation index was 60%. We performed wide local excision with a 30-mm margin, along with resection of intercostal muscles, fasciae and periostea. Neither local recurrence nor distant metastases have occurred in 16 months of follow up. The present case is consistent with malignant solitary fibrous tumor in the subcutis histologically mimicking myxofibrosarcoma or undifferentiated pleomorphic sarcoma, definitively diagnosed by immunoexpression of STAT6. We performed a review of the published work and identified six previously reported patients with malignant superficial solitary fibrous tumor to validate the characteristics of this rare type. Four men and two women were included. The sarcomas involved the head area, trunk and thigh. Only one tumor-associated death occurred despite excision and radiotherapy. Complete excision is a possible treatment choice for this tumor type.

Extrapleural solitary fibrous tumor: A distinct entity from pleural solitary fibrous tumor. An update on clinical, molecular and diagnostic features

Solitary fibrous tumor (SFT) is a mesenchymal neoplasm that was originally described to be localized in the pleura, but thereafter, this has been reported in several anatomic sites. Although the etiology of the neoplasm remains largely unknown, the pathogenesis seems to be related to an NAB2-STAT6 fusion gene due to paracentric inversion on chromosome 12q13. The diagnosis of extrapleural SFT is challenging, owing to its rarity, and requires an integrated approach that includes specific clinical, histological, immunohistochemical, and even molecular findings. Histologically, extrapleural SFT shares morphological features same as those of the pleural SFT because it is characterized by a patternless distribution of both oval- and spindle-shaped cells in a variable collagen stroma. In addition, morphological variants of mixoid, fat-forming, and giant cell-rich tumors are described. A correct diagnosis is mandatory for a proper therapy and management of the patients with extrapleural SFT, as extrapleural SFT is usually more aggressive than pleural form, particularly cases occurring in the mediastinum, retroperitoneum, pelvis, and meninges. Although SFT is usually considered as a clinically indolent neoplasm, the prognosis is substantially unpredictable and only partially related to morphological features. In this context, cellularity, neoplastic borders, cellular atypias, and mitotic activity can show a wide range of variability. We review extrapleural SFT by discussing diagnostic clues, differential diagnosis, recent molecular findings, and prognostic factors.

Orbital solitary fibrous tumor: a clinicopathologic study from a Chinese tertiary hospital with a literature review

Purpose

To report the clinical features, imaging manifestations, histopathology, and immunohistochemical features of several cases of orbital solitary fibrous tumors (SFTs) in a Chinese tertiary hospital, and to undertake a literature review of this rare disease.

Methods

A non-comparative retrospective review of clinical presentations, imaging manifestations, histopathology, and immunohistochemical features as well as the management and disease outcomes of patients with orbital SFT was conducted along with a review of orbital SFT cases in the literature.

Results

This study includes two male and two female patients, with an average age of 53 years. Common presentations among these patients included a palpable subcutaneous mass, swelling of the eyelid, proptosis, diplopia, and vision disturbance. Three patients (cases 2–4) underwent imaging scans. All patients had complete surgical excisions and the tissue was subjected to pathological analysis. One patient (Case 4) experienced a recurrence with malignant transformation and received a re-excision surgery and postoperative radiotherapy. All patients remain alive and well after a minimum follow-up of 12 months (range 12–34 months).

Conclusion

Despite its rare occurrence, we suggest that the possibility of orbital SFTs needs to be considered when a painless, slowly growing orbital mass is identified. Typical characteristic magnetic resonance imaging features of orbital SFTs are iso- or hypointense signals on T1 and T2-weighted images, with marked enhancement. A positive cluster of differentiation 34 (CD34) staining is an important diagnostic clue favoring SFT. Some orbital SFTs are infiltrating, aggressive, or recur with malignant transformation. Therefore, regular long-term follow-up after complete excision is mandatory.

Solitary fibrous tumor of the ischioanal fossa-a multidisciplinary approach to management with radiologic-pathologic correlation

Solitary fibrous tumors are primary mesenchymal tumors, which may occur in any part of the body. Overall, these tumors are considered to have intermediate malignant potential with 5- and 10-year metastasis-free and overall disease-specific survival rates of 74% and 55%, and 89% and 73%, respectively (Demicco et al, 2012). Herein we present an unusual case of solitary fibrous tumors involving the ischioanal fossa in a 19-year-old woman with radiologic-pathologic correlation. This case was complicated by extensive tumor vascularity and was thus managed with preoperative embolization followed by en bloc surgical resection.

Solitary fibrous tumour of the tongue: a series of four cases

Background:

Solitary fibrous tumour is a soft tissue tumour of mesenchymal origin. It was first described in the pleura and has since been reported in many anatomical locations. Thirteen cases in the tongue have hitherto been reported. A positive CD34 result has traditionally been used to confirm the diagnosis, although this is often non-specific to solitary fibrous tumour. To date, nuclear STAT6 expression has not been reported in solitary fibrous tumour of the tongue.

Method:

This paper presents a further four cases of solitary fibrous tumour of the tongue, the largest series to date. Clinical, histopathological and immunohistochemical findings are detailed, including nuclear STAT6 expression.

Results:

All four cases were positive for CD34; two cases showed nuclear expression of STAT6. The tumours were excised completely and there have been no recurrences in at least one year.

Conclusion:

Solitary fibrous tumour should be considered as a differential diagnosis for tongue swellings, with the potential to recur.

Giant Perineal Solitary Fibrous Tumor: A Rare Case Report

Background. Solitary fibrous tumor (SFT) is a fibroblastic mesenchymal tumor that was initially described from the pleura but currently arises at almost every anatomic site. It is usually benign, and surgical resection is curative. SFT involving the perineum is extremely rare. This is the third case report of a perineal SFT in the literature. Case Presentation. We reported an uncommon case of a 64-year-old man presenting with a huge perineal mass that started growing 3 years before his arrival in our service. He was asymptomatic. A contrast-enhanced CT scan revealed a heterogeneous well-circumscribed perineal mass with soft-tissue density. Invasion of the surrounding organs, distal metastasis, and lymph node swelling were absent. The complete resection of mass was done successfully. The specimen was a 23.0 × 14.0 × 8.0 cm encapsulated tumor. Mass weight was 1,170 g. After pathological analysis, we confirmed that the mass was a solitary fibrous tumor. The diagnosis was based on clinical findings and histological morphology and immunohistochemistry study. Conclusion. SFTs are usually indolent tumors with a favorable prognosis. The perineal location is extremely rare. Complete resection of the mass is the treatment of choice.

Desmoplastic Fibroblastoma (Collagenous Fibroma)

We report a case of desmoplastic fibroblastoma/collagenous fibroma in a 42-year-old African-American male. The 10 cm tumor mass was located subcutaneously on the right lower back. Grossly, the tumor was firm and well-circumscribed and, on cut surface, had a white and homogeneous appearance. Microscopically, the tumor was composed of medium-sized spindled and stellatefibroblasts sparsely distributed in a densely fibrous background. No significant nuclear pleomorphism, mitotic figures, or necrosis were identified. The tumor cells were diffusely positive for vimentin and factor XIIIa but were negative for all other markers tested. Ultrastructurally, the tumor cells had features of fibroblasts with abundant rough endoplasmic reticulum. No recurrence has been seen at 5 months after excision.

Solitary Fibrous Tumor of Soft Tissue Clinically Simulating a Chemodectoma

We present a case of a 48-year-old woman with a solitary fibrous tumor localized in the carotid bifurcation clinically simulating a chemodectoma. The tumor was composed of spindle cells with abundant intercellular collagen. These spindle cells were positive for CD34 and negative for chromogranin, S-100 protein, NSE, GFAP, and cytokeratin. This is the first solitary fibrous tumor reported in this location, in the English literature.

Practical Issues for Retroperitoneal Sarcoma

Background

Retroperitoneal sarcoma is rare. Using initial specimens on biopsy, a definitive diagnosis of histological subtypes is ideal but not always achievable.

Methods

A retrospective institutional review was performed for all cases of adult retroperitoneal sarcoma from 1996 to 2015. A review of the literature was also performed related to the distribution of retroperitoneal sarcoma subtypes. A meta-analysis was performed.

Results

Liposarcoma is the most common subtype (45%), followed by leiomyosarcoma (21%), not otherwise specified (8%), and undifferentiated pleomorphic sarcoma (6%) by literature review. Data from Moffitt Cancer Center demonstrate the same general distribution for subtypes of retroperitoneal sarcoma. A pathology-based algorithm for the diagnosis of retroperitoneal sarcoma is illustrated, and common pitfalls in the pathology of retroperitoneal sarcoma are discussed.

Conclusions

An informative diagnosis of retroperitoneal sarcoma via specimens on biopsy is achievable and meaningful to guide effective therapy. A practical and multidisciplinary algorithm focused on the histopathology is helpful for the management of retroperitoneal sarcoma.

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.

Intracranial solitary fibrous tumors: A report of two cases and a review of the literature

Solitary fibrous tumors (SFTs) are uncommon, with the pleura as a site of predilection. Central nervous system SFTs, particularly intracranial SFTs, are extremely rare. The lesions are generally benign and localized, and surgery is the main therapeutic solution. The current study reports the cases of a patient who presented with right haunch pain, right leg weakness and paresthesias for several months, and a patient with a history of unexpected loss of consciousness. Magnetic resonance imaging revealed the presence of lesions, with a spindle cell morphology evident on pathological examination. The immunohistochemical examination demonstrated a strong immunoreaction for cluster of differentiation 34, which supported the diagnosis of an SFT. Following a near-total resection, the patients had a good neural prognosis. The present study also provides a literature review, discussing the imageological and pathological characteristics of SFT, and the diagnostic methods that aid in distinguishing the entity from other spindle-cell central nervous system tumors.

Clinicopathologic and immunohistochemical features of five new cases of solitary fibrous tumor of the oral cavity

OBJECTIVE

To describe the clinicopathologic and immunohistochemical features of five cases of oral solitary fibrous tumor.

STUDY DESIGN

Clinical data were collected from charts of two oral pathology laboratories of Latin America. All cases were evaluated by conventional hematoxylin and eosin staining and an extended immunohistochemical panel comprising vimentin, CD34, CD99, bcl-2, HHF-35, smooth muscle actin, calponin, S-100 protein, h-caldesmon, and Ki-67.

RESULTS

The study included 1 male (20%) and 4 female (80%) patients, with a median age of 43 years. The most common affected site was the buccal mucosa (40%). Tumors were characterized by proliferation of spindled and ovoid cells in a variably vascular and collagenized stroma. All tumors were positive for vimentin, CD34, bcl-2, and CD99. Recurrence was not observed after complete surgical enucleation.

CONCLUSIONS

Oral solitary fibrous tumors usually appear as well-delimited submucous nodules with a firm-rubbery consistency and covered by intact mucosa. Immunoreactivity for CD34, bcl-2, and CD-99 is helpful to confirm the diagnosis.

Cellular angiofibroma in women: a review of the literature

Cellular Angiofibroma (CA) represents a quite recently described mesenchymal tumour that occurs in both genders, in particular in the vulvo-vaginal region in women and in the inguino-scrotal area in men. The first description of this tumour dates from Nucci et al. article in 1997; since then, the literature reports different reviews and case report of this tumour in both genders, but no article specifically addressing CA treatment and follow-up in women. In this review we collected all 79 published female CA cases, analyzing the clinical, pathological and immunohistochemical features of the tumour.

CA affects women mostly during the fifth decade of life, it is generally a small and asymptomatic mass that mainly arises in the vulvo-vaginal region, although there are reported pelvic and extra-pelvic cases. The treatment requires a simple local excision due to an extremely low ability to recurrent locally and no chance to metastasize. Throughout the immunohistochemical and pathological findings it is also easily possible a differential diagnosis from the other soft tissue tumours which affect the vulvo-vaginal area, such as spindle cell lipoma, solitary fibrous tumour, angiomyofibroblastoma and aggressive angiomyxoma.

Needle biopsy of mesenchymal lesions of the head and neck: Evolving concepts and new strategies for diagnosis

Sarcomas are a rare and heterogeneous group of neoplasms that can be a significant diagnostic challenge in routine practice. Recent advances in the understanding of molecular mechanisms underlying oncogenesis have led to an array of novel diagnostic tools. Here we review several sarcomas of the head and neck region, focusing on neoplasms with new molecular findings and highlighting novel diagnostic tools.

Solitary fibrous tumor of the submandibular region

Solitary fibrous tumors (SFTs) are a rare type of neoplasm that originate from the pleura. Although SFTs may occur in a variety of extrathoracic regions, they are considered to be rare in the submandibular region. The current study presents the case of a 39-year-old female with a 3×4-cm, fibro-elastic, movable, painless nodule in the right side of the submandibular region. The patient exhibited no other clinical manifestations in the head and neck region. A computed tomography scan demonstrated the presence of a well-defined, slightly low-density nodular shadow measuring 2.6×3.3×3.8 cm, in proximity to the right submandibular gland, with mild contrast enhancement and no association with the adjacent lymph nodes. The lesion was surgically excised, and following histopathological and immunohistochemical analysis, immunohistochemical staining determined that the lesion was positive for cluster of differentiation (CD)34, CD99 and vimentin, and negative for desmin, CD31 and S-100; therefore, a diagnosis of an SFT was determined. The patient has so far been followed up for 22 months, with no signs of recurrence or metastases. The present study also discusses the clinical, histopathological and immunohistochemical features, treatment strategies and potential clinical outcomes of SFTs. The study proposes that, although rare, SFTs of the submandibular region should be included in the differential diagnosis of soft-tissue tumors in the submandibular region.

Subcutaneous Solitary Fibrous Tumor

We describe a unique case of subcutaneous solitary fibrous tumor (SFT) in a 56-year-old female patient. The patient had been aware of a painless soft mass in her back for ten years. The lesion was surgically excised. Histological examination revealed that the well-defined mass was composed of a proliferation of spindle-shaped fibroblastic cells and polygonal cells embedded in a fibrous matrix corresponding to the so-called "patternless pattern". A prominent pericytomatous pattern (hemangiopericytoma-like structures), focal myxoid changes, and thick hyalinized collagen fibers were also observed. Immunohistochemical stainings for CD34 and bcl-2 were positive in the tumor cells. These features are compatible with SFT. We suggest that SFT should be included in the differential diagnosis of subcutaneous spindle cell tumors.

Clinicopathological findings in a case series of abdominopelvic solitary fibrous tumors

Solitary fibrous tumors (SFTs) represent a rare type of soft tissue tumor. Extrathoracic SFTs (ESFTs) in the soft tissues of the abdominopelvic cavity are extremely rare. Between January 2002 and January 2013, 10 patients were identified with abdominopelvic SFTs at the Northern Jiangsu People's Hospital. The clinicopathological data, treatment and follow-up results were retrospectively analyzed in this study. Patients included four females and six males, whose age ranged between 21 and 75 years (mean, 53.3 years). The maximum diameter of the tumors was 2.5-28 cm (mean, 12.7 cm). Two cases were diagnosed as malignant variants of ESFTs. R0 resection was performed in eight patients, while one patient underwent R1 resection, and one patient received palliative chemotherapy for an inoperable mass. Follow-up time ranged between 6 and 126 months (mean, 50 months). The patient with R1 resection suffered a local relapse, and the patient receiving palliative chemotherapy succumbed to the disease. The remaining eight patients remained free of disease. Abdominopelvic SFTs usually reveal an indolent process, although the majority of tumors in the present study were of giant size when diagnosed. The risk of local recurrence and metastasis correlates with tumor size and the histological status of surgical margins. The preferred treatment is complete resection followed by extended follow-up surveillance.

Solitary fibrous tumor of the soft palate: A report of two cases

Solitary fibrous tumors (SFTs) are a unique group of mesenchymal neoplasms of fibroblastic or myofibroblastic origin and are extremely rare in the oral cavity. The present study reported two additional cases of SFTs in the soft palate, along with the computed tomography characteristics, which demonstrated well-circumscribed soft tissue lesions with marked and homogenous enhancement. Following wide resection, one of the cases showed certain malignant pathological characteristics, including infiltration of mucinous gland, hypercellularity, nuclear atypia and weak positive staining for S-100. In our experience, SFTs should be considered as a differential diagnosis when a well-circumscribed and solid mass in the soft palate is identified.

Solitary fibrous tumors/hemangiopericytomas with different variants of the NAB2-STAT6 gene fusion are characterized by specific histomorphology and distinct clinicopathological features

Recurrent somatic fusions of the two genes, NGFI-A-binding protein 2 (NAB2) and STAT6, located at chromosomal region 12q13, have been recently identified to be presumable tumor-initiating events in solitary fibrous tumors (SFT). Herein, we evaluated a cohort of 52 SFTs/hemangiopericytomas (HPCs) by whole-exome sequencing (one case) and multiplex RT-PCR (all 52 cases), and identified 12 different NAB2-STAT6 fusion variants in 48 cases (92%). All 52 cases showed strong and diffuse nuclear positivity for STAT6 by IHC. We categorized the fusion variants according to their potential functional effects within the predicted fusion protein and found strong correlations with relevant clinicopathological features. Tumors with the most common fusion variant, NAB2ex4-STAT6ex2/3, corresponded to classic pleuropulmonary SFTs with diffuse fibrosis and mostly benign behavior and occurred in older patients (median age, 69 years). In contrast, tumors with the second most common fusion variant, NAB2ex6-STAT6ex16/17, were found in much younger patients (median age, 47 years) and represented typical HPCs from deep soft tissue with a more aggressive phenotype and clinical behavior. In summary, these molecular genetic findings support the concept that classic pleuropulmonary SFT and deep-seated HPC are separate entities that share common features but correlate to different clinical outcome.

Dendritic fibromyxolipoma in the right inguinal and perineum regions: a case report and review of the literature

Abstract

A 32-year-old woman presented with a slow-growing, painless, subcutaneous lesion in the right inguinal and perineum regions. The mass was 24.0 cm × 10.5 cm × 5.0 cm in size, well circumscribed, mobile, and rubbery. Microscopically, the resected mass was mainly composed by a proliferation of small spindle or stellate cells, variably admixed with mature adipose tissue, embedded within an abundant myxoid and collagenized stroma. Immunohistochemically, the spindle and stellate cells were strongly positive for vimentin, CD34, and bcl-2 antibodies but not for smooth muscle actin and desmin. The tumor was diagnosed as dendritic fibromyxolipoma based on the typical findings of histology and immunohistochemistry. Clinical follow-up of 9 months after surgery revealed no evidence of recurrence. We report the first case of dendritic fibromyxolipoma in the right inguinal and perineum regions and discuss the different diagnosis.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1313680868103019.

Extrathoracic location and "borderline" histology are associated with recurrence of solitary fibrous tumors after surgical resection

BACKGROUND

Most solitary fibrous tumors (SFTs) are cured by complete resection, but many recurrent and metastatic SFTs do not respond to treatment and are fatal. Malignant histology, defined by England's pathologic criteria, is strongly associated with recurrence, but some benign SFTs still behave aggressively. Several studies have suggested that extrathoracic SFTs have a worse prognosis. We reviewed thoracic and extrathoracic SFTs from our institution to determine if extrathoracic location is associated with recurrence, independent of malignant histology.

METHODS

With IRB approval, we retrieved patient pathology reports from the Johns Hopkins Surgical Pathology database between 1991 and 2011 and included 83 SFT patients in our analysis. Patient history and outcomes were obtained from the medical record and primary care physicians. Predictors of recurrence were analyzed by univariate and multivariate analysis and survival determined by the Kaplan-Meier method.

RESULTS

Of the 83 patients, 59 had extrathoracic SFTs in neurologic (n = 24), extremity or head/neck (n = 13), or visceral/intraabdominal (n = 22) sites. A total of 74 SFTs were classified benign and 9 as malignant. Of the 14 recurrences, 13 occurred in extrathoracic SFTs; only 7 were classified as malignant. Multivariate analysis confirmed that malignant histology had the strongest association with recurrence, but extrathoracic location also independently predicted recurrence. A total of 20 benign SFTs possessed 1 or more of England's criteria but to an insufficient degree for malignant classification. These "borderline" SFTs were more likely to recur than benign SFTs without these features.

CONCLUSIONS

Extrathoracic and "borderline" SFTs with any of England's criteria have a higher risk of recurrence.

Solitary fibrous tumor of the buccal vestibule: report of two cases

Solitary fibrous tumor (SFT) is a rare benign tumor that occurs most frequently in the pleura. It is considered rare in the maxillofacial area. Two new cases of SFT of the buccal vestibule are reported. The previously reported cases of oral SFT are reviewed. The tumors were composed of spindle-shaped cells that were arranged haphazardly and were positive for CD-34, BCL-2, CD-99 and vimentin. Although rare, SFT should be included in the differential diagnosis of oral soft tissue tumors. The clinical presentation and imaging can provide the clinician a better tool for preoperative diagnosis.

Desmoplastic fibroblastoma presenting as a parotid tumour: a case report and review of the literature

Desmoplastic fibroblastomas (DFs) are rare fibrous soft tissue tumours that usually arise in subcutaneous tissue or skeletal muscle in a variety of anatomical sites. These lesions most frequently present as painless, slow-growing mobile masses. A case of DF is described in a 47-year-old man who presented with a painless right parotid mass of 2 months duration. At surgery, the lesion was attached to the tail of the right parotid gland. Histopathological examination demonstrated a fibrous lesion comprising spindled and stellate shaped fibroblasts with focal myxoid stromal change. The features were consistent with a DF. This report documents a rare parotid lesion which may mimic other more common parotid gland neoplasms.

Solitary fibrous tumors of the soft tissues: imaging features with histopathologic correlations

Purpose

To describe the imaging features of soft tissue solitary fibrous tumors, with histopathological correlations and clinical outcome.

Material and methods

Twenty-seven patients with histologically proven SFTs were retrospectively evaluated. Imaging studies included six radiographs, five U/S studies, eighteen CT scans, fourteen MRI exams, and one angiography.

Results

On CT scans, two lesions were isodense and five were mildly hypodense compared to muscle while 11 lesions appeared heterogeneous-mixed of iso and hypodense areas. Heterogeneous enhancement was depicted in 13 lesions and four lesions enhanced homogeneously. Six lesions were partially calcified. On T1W MR images, seven lesions were isointense and one was slightly hyperintense relative to adjacent muscles while five lesions appeared heterogeneous-mixed of iso and hypointense areas. T2W images showed high SI in two cases and heterogeneous-mixed in seven cases. Enhancement was heterogeneous in six and homogeneous in four lesions. Patchy unenhanced areas (on CT and T1W MR images) along with patchy areas of low to markedly high SI on T2W images were depicted in 19 lesions. The enhanced portions correlated to areas of increased vascularity and cellularity. The four clinically more aggressive lesions could not be predicted on imaging.

Conclusion

Typical soft tissue SFTs are deep masses made of isodense and isointense areas relative to adjacent muscles mixed with hypodense and hypointense areas on unenhanced CT and MR T1W respectively. Variable enhancement patterns and mixed to high signal intensities on MRT2W are attributed to tumor’s cellularity, vascularity, collagen distribution and/or degeneration. Heterogeneity of SFTs affects imaging features on MRI and CT modalities. The biological behavior of soft tissue SFTs can not be predicted based solely either on histopathologic or imaging evaluation.