Primary solitary fibrous tumor (SFT) in the retroperitoneum

Possible Genetic Links Between Solitary Fibrous Tumor and Pancreatic Cancer: A Rare Case of Solitary Fibrous Tumor and Pancreatic Cancer Concurrence

Pancreatic ductal adenocarcinoma is the most prevalent form of pancreatic cancer, originating in the duct lining of the pancreas. The simultaneous occurrence with a solitary fibrous tumor (SFT) represents an unexpected finding. We present a case involving a 64-year-old female with synchronous pancreatic cancer and SFT. The patient initially experienced severe abdominal pain, visible jaundice, and itching. Diagnostic imaging revealed a mass in the head of the pancreas and a soft tissue mass in the right hemipelvis. Further investigations included histological examination, immunohistochemistry, and genetic testing. Subsequently, the patient underwent appropriate management, which involved the excision of both masses and radiochemotherapy. The discussion focuses on the genetic linkages in this rare presentation, aiming to identify treatment connections for both tumors. Throughout this case report, our aim is to contribute to enriching the limited literature with new insights and underscore the importance of identifying genetic linkages between both tumors which may lead to more effective management strategies and better treatment outcomes.

Big insulin-like growth factor 2-producing multiple solitary fibrous tumors treated with debulking surgery: A case report

BACKGROUND

Non-islet cell tumor hypoglycemia (NICTH) is a rare paraneoplastic syndrome caused by a tumor-producing high molecular weight form of insulin-like growth factor 2 (IGF2) known as big IGF2. The only curative treatment for this condition is surgical resection of the responsible tumors. However, this may not be feasible in cases with multiple metastases at diagnosis of NICTH, and no standard treatment strategy for multiple tumors has been established. The effects of pharmacological therapies including somatostatin analogs are often inefficient and remain difficult to predict.

CASE DESCRIPTION

A 68-year-old man was admitted to our hospital due to impaired consciousness and severe hypoglycemia. His medical history included diagnosis of a left temporal solitary fibrous tumor (SFT) at the age of 48 years, after which local recurrent and metastatic tumors were repeatedly resected. Four years before admission, multiple intraabdominal and subcutaneous tumors were detected and, being asymptomatic, were managed conservatively. Laboratory exam on admission demonstrated hypoglycemia accompanied with low serum insulin and IGF1 levels. Computed tomography (CT) scan revealed multiple intraabdominal and subcutaneous tumors increasing in size. Serum big IGF2 was detected on immunoblot analysis, and he was diagnosed as NICTH. In addition, tumor uptake was observed on ⁶⁸Ga-labelled 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-d-Phe¹-Tyr³-octreotide positron emission tomography/CT (DOTATOC-PET/CT). Since larger tumor is more suspicious about responsible producibility of big IGF2, we planned to resect large ones preferentially and reduce the amounts of residual tumors. Debulking surgery was performed by removing eleven intraabdominal tumors; the hypoglycemia was then completely corrected. Histological analyses revealed the resected tumors to be metastases of SFT having somatostatin receptor 2 expression. In immunoblot analysis, the resected tumors were found to be positive for big IGF2; serum big IGF2 was undetectable after surgery.

CONCLUSION

We present a case of NICTH with multiple metastatic SFTs. We strategically performed debulking surgery, which led to remission of hypoglycemia. This result demonstrates a pioneering practical solution for NICTH cases with multiple tumors. In addition, in cases of SFTs presenting with NICTH, positivity of DOTATOC-PET/CT as well as single-dose administration of octreotide may be predictive of the efficacy of somatostatin-based therapy.

Mesentery solitary fibrous tumor with postoperative recurrence and sarcomatosis: A case report and review of literature

BACKGROUND

Solitary fibrous tumors are rare neoplasms of mesenchymal origin. They are often of low malignant potential and rarely metastasize. They frequently arise from the pleura and can occur at any soft tissue site in the body. However, these tumors rarely develop in the mesentery, peritoneal cavity or peritoneum.

CASE SUMMARY

We report on a scarce case of solitary fibrous tumor of the rectal mesentery showing sarcomatosis about 4 years after previous tumor resection. This 69-year-old male had no clinical symptoms but was transferred to our hospital because of a suspected tumor recurrence from follow-up abdominal computed tomography. Tumor markers (CEA, CA 19-9 and CA 125) were within the normal range. Open laparotomy showed sarcomatosis, and pathology confirmed its mesenchymal origin and diagnosis as the solitary fibrous tumor. Our case may be the second recurrent mesentery solitary fibrous tumor reported to date, and the only one with progression to sarcomatosis. There has been no evidence of recurrence in follow-up at the 28^th mo after extensive intra-operative peritoneal lavage and cytoreductive surgery.

CONCLUSION

Although there are few risk factors of cancer recurrence in this patient, careful long-term follow-up after cytoreductive surgery is necessary.

Solitary Fibrous Tumors Arising from Bilateral Ovaries: A Case Report and Review of the literature

BACKGROUND

A solitary fibrous tumor (SFT) is a distinct mesenchymal neoplasm. It was originally described as a tumor localized to the pleura but was later reported in several other anatomic sites and exhibited a wide spectrum of histological features. Owing to its rarity, the diagnosis of extrapleural SFT is challenging and requires an integrated approach comprising specific clinical, imaging, histological, and immunohistochemical findings.

CASE PRESENTATION

Herein, we report the imaging findings of a rare case of SFT arising from bilateral ovaries confirmed by surgical excision and histological examination. No adjuvant radiotherapy or chemotherapy was given to the patient, and she was disease-free with no evidence of recurrence or metastasis at the 96-month postoperative follow-up. Although it mostly follows a favorable course, SFT is notoriously difficult for prognostication because of its propensity for late relapse or even metastases in 10-39% of cases.

CONCLUSION

Close follow-up is recommended because of the limited information on its long-term behavior.

Solitary fibrous tumors: Clinical and imaging features from head to toe

Solitary fibrous tumors (SFTs) are rare fibroblastic mesenchymal tumors that are usually benign with variable malignant potential. They can develop in any organ due to their spindle cell origin. The exact etiology of solitary fibrous tumors is unknown. The majority of SFTs are benign with 10-30% of them exhibiting aggressive and malignant features. The aggressiveness of this type of tumor is not associated with its histological features, which makes surgical resection the treatment of choice. We will review the clinical and radiological features and possible differential diagnoses of SFTs according to their anatomical sites following the World Health Organization 2020 classification.

A Comprehensive Review on Solitary Fibrous Tumor: New Insights for New Horizons

Simple Summary

Solitary fibrous tumor (SFT) is a malignant condition that exhibits different clinical behaviors ranging from low to high aggressive SFT, with dedifferentiated SFT (DD-SFT) being the fastest-growing subtype. Even when surgery alone provides curation rates above 60%, recurrences do occur in a fraction of patients where surgery is unable to provide disease control. Among the systemic therapeutic options, antiangiogenic compounds have shown higher efficacy than chemotherapy by indirect comparisons. Furthermore, rotating different antiangiogenics, at the progression time, has been shown to be effective. The exception is DD-SFT since it is resistant to antiangiogenics but can respond to chemotherapy. This comprehensive review also analyzes the underlying molecular components that play a key role in SFT origin and aggressiveness. The discovery in 2013 of anomalous fusion genes between NAB2 and STAT6 was determinant to increase the knowledge on the molecular drivers in SFT that could be potential targets for future therapies.

Abstract

Solitary fibrous tumor (SFT) is a rare mesenchymal, ubiquitous tumor, with an incidence of 1 new case/million people/year. In the 2020 WHO classification, risk stratification models were recommended as a better tool to determine prognosis in SFT, to the detriment of “typical” or “malignant” classic terms. The risk for metastasis is up to 35–45%, or even greater, in series with a longer follow-up. Over the last few decades, advances in immunohistochemistry and molecular diagnostics identified STAT6 nuclear protein expression and the NAB2–STAT6 fusion gene as more precise tools for SFT diagnosis. Recent evidence taken from retrospective series and from two prospective phase II clinical trials showed that antiangiogenics are active and their sequential use from first line should be considered, except for dedifferentiated SFT for which chemotherapy is the best option. Since the fusion transcript driver’s first description in 2013, new insights have been brought on key molecular events in SFT. This comprehensive review mainly focuses on the superior efficacy of antiangiogenics over chemotherapeutic agents in SFT, provides the current knowledge of key molecules that could co-drive the SFT behavior, and suggests new target candidates that deserve to be explored in preclinical and clinical research in SFT.

Surgical treatment of primary solitary fibrous tumors involving the pelvic ring

The surgical treatment of primary solitary fibrous tumors (SFT) involving the pelvic ring has not been reported previously. In this study, we aimed to evaluate the efficacy of surgical treatment for this disease. From 2009 to 2015, 13 patients underwent tumor resection at our hospital, with an average age of 49.5 years (27–68 years). Four patients underwent en bloc resection, and 9 patients underwent piecemeal resections. A Chi-square test was used to compare the postoperative recurrence rates between the en bloc resection and the piecemeal resection groups (p = 0.68), and no significant difference was found between the benign and malignant solitary fibrous tumor groups (p = 0.44). The 5-year survival rate of the patients in this study was 83.3%, and the 5-year progression-free survival rate was 63.5%. The progression-free survival rate was not significantly different between the en bloc resection and piecemeal resection groups (p = 0.97). Piecemeal resection can also achieve acceptable local control, particularly for patients with sacral tumors, as they may achieve even better postoperative function with sacral nerve preservation. Recurrence and metastasis occur relatively late in the course of this disease. Therefore, long-term follow-up is required.

Late Onset of Non-islet Cell Tumor Hypoglycemia Managed via Multidisciplinary Treatment in a Patient with a Solitary Fibrous Tumor

Solitary fibrous tumor (SFT) is a rare subtype of soft tissue sarcoma (STS). We herein describe a case of late onset of non-islet cell tumor hypoglycemia (NICTH) that was managed via multidisciplinary treatment in a patient with SFT. A 67-year-old man previously diagnosed with SFT 4 years prior to this presentation and treated with several rounds of surgery, presented with massive tumors. Eighteen months following his prescribed chemotherapy, the patient developed hypoglycemia. He was diagnosed with NICTH, after confirming the presence of high molecular weight insulin-like growth factor-2. This case suggests that paraneoplastic syndrome can occur even in cases of rare cancers, such as STS.

Doege-Potter Syndrome, cause of nonislet cell tumor hypoglycemia: the first case report from Nepal

Doege–Potter syndrome (DPS), a paraneoplastic syndrome, presents as a hypoinsulinemic hypoglycemia from the ectopic secretion of insulin-like growth factor II from a solitary fibrous tumor which may be intrapleural or extrapleural in origin. We report a case of severe hypoglycemia in a 70-year old female initially admitted for resection of left sided solitary fibrous tumor of pleura. Investigation revealed true hypoglycemia, and DPS was diagnosed. The tumor was completely resected, after which no further hypoglycemic episodes were seen in 2 years follow-up. This is the first case of solitary fibrous tumor of pleura with DPS reported from Nepal.

Malignant solitary fibrous tumor in retroperitoneum: A case report and literature review

RATIONALE

Solitary fibrous tumor (SFT) is a rare mesenchymal tumor occurs in various sites. Malignant SFT in retroperitoneum is extremely rare.

PATIENT CONCERNS

We report a case of malignant retroperitoneal SFT in a 59-year-old man presented with right flank pain for 1 month.

DIAGNOSES, INTERVENTIONS AND OUTCOMES

A laparotomy and resection of the tumor were performed, the histopathologic and immunohistochemical findings were consistent with malignant retroperitoneal SFT. No adjuvant treatment was performed, and the patient had no signs of recurrence or metastasis at the 12 months follow-up.

LESSONS

Complete surgical excision is the basic treatment principle for malignant retroperitoneal SFT. The histologic features and the Ki-67 label index are helpful for the diagnosis of malignant SFT.

Radiological diagnosis of perinephric pathology: pictorial essay 2015

The perinephric space, shaped as an inverted cone, sits between the anterior and posterior renal fasciae. It can play host to a variety of clinical conditions encountered daily in the reporting schedule for a radiologist. Lesions may be classified and diagnosed based on their imaging characteristics, location and distribution. A broad range of differential diagnoses can be attributed to pathology sitting within this space, often without clinical signs or symptoms. An understanding of commonly encountered conditions affecting the perinephric space, along with characteristic imaging findings, can illustrate and often narrow the likely diagnosis. The aim of this essay is to describe commonly encountered neoplastic and non-neoplastic entities involving the perinephric space and to describe their key imaging characteristics.

TEACHING POINT

• Despite often a bulky disease, perinephric lymphoma does not produce obstruction or stenosis. • In primarily fatty masses, defects within the renal capsule likely represent angiomyolipoma. • Consider paraganglioma if biopsy is planned; biopsy may lead to catecholamine crisis.

Integrally calcified solitary fibrous tumor in the retroperitoneum: a case report and review of the literature

Solitary fibrous tumor (SFT) is a rare stromal neoplasm and usually occurs in the thoracic cavity. We here report a case of retroperitoneal SFT with prominent calcification. A 64-year-old man presented with an incidentally detected retroperitoneal mass in the right upper abdomen. Imaging tests indicated an integrally calcified mass. The lesion was observed for 2 years and laparoscopically resected according to the patient's wish. Microscopically, the mass was mostly occupied by calcification and proliferous spindle cells were scattered with positive CD34 expression. We diagnosed morphologically benign SFT and the patient remained disease-free 1 year after the excision. There has been no report of such integrally calcified SFT. Retroperitoneal SFT is difficult to make a preoperative diagnosis, and careful follow-up after the excision is recommended because morphological malignancy does not always correspond to clinical malignancy.

Late recurrence of a malignant hypoglycemia-inducing pelvic solitary fibrous tumor secreting high-molecular-weight insulin-like growth factor-II: A case report with protein analysis

The present study reports a case of recurrent malignant pelvic solitary fibrous tumor (SFT) that induced non-islet cell tumor hypoglycemia via high-molecular-weight insulin-like growth factor-II in a 72-year-old male patient. The tumor recurred ~12 years after the complete resection of the original mass. The recurrent tumor, which had directly invaded the left ureter and perirectal fat tissue, could not be completely excised due to its fragility and adhesiveness. At 13 days post-surgery, the patient presented with rectal perforation, and an urgent rectal resection and colostomy was performed. Neither recurrence of the tumor nor hypoglycemic symptoms were observed 9 months after the surgery. High molecular weight insulin-like growth factor-II was detected in the serum and tumor specimens by western blot analysis and immunohistochemistry. The present case report suggests that certain SFTs can relapse even ≥10 years after a presumed complete resection of the primary tumor, and that performing a safe and complete resection of these tumors can be challenging, due to their adhesiveness or physical presentation; therefore, the indications for surgery should be considered with caution.

Solitary Fibrous Tumor of the Kidney Developing Local Recurrence

Solitary fibrous tumor (SFT) of the kidney is a rare entity and usually displays a favorable prognosis. We herein report a second case of renal SFT developing local recurrence. A 50-year-old man was referred to our hospital because of a left renal mass. An abdominal CT detected a large renal tumor and radical nephrectomy was performed with a possible diagnosis of renal cell carcinoma. The resected tumor size was measured at 17 × 11 × 8 cm. Grossly, necrosis was observed in central lesion of the tumor but hemorrhage was not observed. Microscopically, the tumor consisted of spindle-shaped cells with scant cytoplasm accompanied by hyalinized collagenous tissue, which displayed hemangiopericytomatous patterns. The cellularity was normal and nuclear pleomorphism was not observed. Ki-67 labeling index was less than 3%. The pathological diagnosis of SFT was made without obvious malignant findings. Three years after the surgery, a follow-up CT scan detected a mass lesion in the tumor bed. Surgical resection was performed and the resected tumor was compatible with local recurrence of the SFT without obvious malignant findings. Renal SFT should be carefully monitored even in the absence of obvious malignant findings.

Outcome of surgery in patients with solitary fibrous tumors of the pleura

Background

Solitary fibrous tumor of the pleura is rare, and the origin is submesothelial tissue. These tumors are seen in lung infrequently, and most are benign. We report our experience in the diagnosis and treatment of patients with solitary fibrous tumors of the pleura.

Methods

We studied 13 patients (6 men and 7 women, aged 26 to 76 years) with a diagnosis of benign solitary fibrous tumor of the pleura who were operated on from 2001 to 2014. One had a recurrent tumor after 10 years, and the others had primary tumors. Our approach was complete resection in all cases.

Results

After surgical excision, the most essential characteristic on histopathology was a neoplastic lesion composed of spindle-shaped tumor cells with hyperchromatic nuclei and eosinophilic bands of collagen. On immunohistochemical analysis, the cells were positive for desmin and negative for actin, synaptophysin, chromogranin, and CD117.

Conclusions

The essential step in the treatment of a patient with a diagnosis of benign solitary fibrous tumor of the pleura is complete resection. These patients should be followed up for a long time because of the possibility of late recurrence. Due to the rarity of these tumors, there has been no systematic assessment of the role of adjuvant therapy for benign solitary fibrous tumor of the pleura.

Retroperitoneal solitary fibrous tumor: surgery as first line therapy

BACKGROUND

Solitary fibrous tumors (SFT) of the retroperitoneum are rare spindle cell neoplasms, with a paucity of data on treatment outcomes. We hypothesized that surgical excision offered acceptable outcomes in SFTs.

METHODS

The National Cancer Database (NCDB) was used to identify patients with SFT from 2004 to 2011. Primary outcome measures were 30 day mortality and overall survival. Descriptive analyses were performed. Furthermore, a systematic review of published literature was conducted after creating a pre-specified search strategy.

RESULTS

Of 51 patients in the NCDB, 58.8 % (n = 30) were males, with a median age 60 years (IQR 49-72 years). Median tumor size was 16 cm (IQR 11-21 cm). Surgical resection was performed in 92.2 % (n = 47) with 63.8 % (n = 30) having a margin negative resection. Peri-operative mortality was 2.1 % (n = 1). Of survival outcomes available for 18 patients, the median OS was 51.1 months. From the systematic review, we identified 8 studies, with 24 patients. Median age and tumor size was similar to the NCDB [47.5 years (IQR 39-66.5 years), 12 cm (IQR 7-17 cm)]. Majority [91.7 % (n = 22)] underwent surgical excision alone while one received adjuvant chemotherapy and none received radiation. After median follow up of 54 months (IQR 28-144 months), 79.2 % (n = 19) were alive without disease. Three patients (12.5 %) died of disease, one was alive with disease and one was lost to follow up. Recurrence was reported in 16.7 % (n = 4) of patients.

CONCLUSION

Complete surgical excision is a viable treatment modality for retroperitoneal SFT leading to long term survival. Low recurrence rates would argue against the need for routine adjuvant radiation or chemotherapy.

Imaging findings of solitary fibrous tumor in the abdomen and pelvis

PURPOSE

The purpose of this study was to investigate the imaging characteristics of solitary fibrous tumor (SFT) in the abdomen and pelvis.

METHODS

Nine cases of SFT confirmed by surgery and pathology were retrospectively analyzed in terms of computed tomography (CT, eight cases) and magnetic resonance imaging (MRI, one case).

RESULTS

SFT were located in the retroperitoneum (4/9), abdominal cavity (1/9), pelvis (4/9). Eight cases were single (8/9) and one case (1/9) with three tumors. The average tumor size of 11 lesions was 9.7 cm (4.7-20 cm). Nine tumors were round or ovoid, and two lesions were irregular. The CT value of the plain scans ranged from 33 to 43 Hounsfield units (HU, mean 37.6 HU) in five cases. Arterial-phase CT found solid parts demonstrate avid enhancement (eight cases) and five of them presented with multiple circuitous vessels along the periphery with a CT value of 68-89 HU (mean 76.6 HU). In the venous and delayed phases, enhancement was strengthened progressively. The CT values at venous (eight cases) and delayed phases (five cases) were 108-115 and 112-123 HU respectively, with averages of 109.8 and 114.8 HU. Patch or nodular no-enhanced areas were observed in eight cases during the enhanced phases. One case showed isointensity on T1-weighted images and high signal intensity on T2-weighted images accompanied by linear or curvilinear hypointense lines. Intense enhancements along with linear no-enhancement areas are seen in the arterial and venous phases.

CONCLUSION

The possibility of SFT should be considered when a single or multiple masses with sharp border, inhomogeneous density or signal are detected, especially, with inhomogeneous intense enhancement in the arterial phase being maintained in the venous and delayed phases.

A case of solitary fibrous tumor in the pelvis presenting massive hemorrhage during surgery

Solitary fibrous tumors (SFTs) are unique soft-tissue tumors of submesothelial origin. These tumors are mainly located in the pleural space but they can be originated within a variety of sites, including the abdomen, the pelvis, the soft tissues and the retroperitoneum. SFTs from all sites are usually benign, and the surgical resection is curative in almost all cases. According to the review of literatures, during the surgical resection, massive hemorrhage could occur due to the hypervascular nature of SFTs. This is a case report on SFT in the pelvis presenting great vessel injury, which resulted in life threatening hemorrhage during the resection of tumor. We wish this paper alerts gynecologists about the risk of massive bleeding during the resection of tumor located at adjacent to great vessels in the pelvis.

CT features of retroperitoneal solitary fibrous tumor: report of three cases and review of the literature

CT findings in three cases with solitary fibrous tumors (SFTs) confirmed by histopathology and immunohistochemistry were reviewed retrospectively, and compared with pathological results. The three tumors were large, well-defined, and smooth contour masses and SFT consisted of solid components of two different densities. On enhanced CT scans, tumors were strongly enhancing, the multiple vascular shadows were seen within the tumor in the arterial phase. There is progressive enhancement from the arterial to the venous phase, and the tumor capsule can be observed. Histologically, the tumors are composed of spindle cells within a background of collagen stroma, and showed a wide range of growth patterns, alternating hypercellular (tumor cell-rich) and hypocellular (collagen-rich) areas. The diagnosis is confirmed by characteristic positive immunohistochemical staining for CD34.

Large solitary fibrous tumour of the retroperitoneum: a case report and review of the literature

INTRODUCTION

This report describes an unusual case of a large solitary fibrous tumour (SFT) arising in the retroperitoneum.

CASE PRESENTATION

A 53-year-old woman presented at the Emergency Department with urinary retention and lumbar pain. The urological examination was negative, whereas a presacral retroperitoneal mass was disclosed on ultrasound. The laboratory studies, including tumour markers, were negative. On laparotomy, it was not possible to remove the mass completely due to the difficulty of dissecting it free of the sacrum. Grossly, the fragment had a yellowish-white surface, with areas of necrosis and haemorrhage. On immunohistochemistry, tumour cells were positive for CD34, CD99 and Bcl-2 and negative for CD45, synaptophysin, chromogranin, S100, neuron-specific enolase, CK AE1-AE3, CK7, Wilms' tumour 1, smooth muscle actin, factor VIII, myogenin, epithelial membrane antigen, thyroid transcription factor-1 and CD117, leading to a diagnosis of SFT. Molecular investigation ruled out synovial sarcoma.

CONCLUSION

Although SFT usually has a favourable prognosis, close follow-up is recommended due to the limited information on its long-term behaviour.

Renal myopericytoma: A case report with a literature review

Myopericytoma is a rare neoplasm that generally arises from the skin and superficial soft tissues of distal extremities, and is particularly rare in the visceral organs. The current report presents a case of giant myopericytoma showing kidney involvement, which is extremely rare. A 39-year-old male presented to the Department of Urology with a 2-month history of a painless and palpable mass in the region of the left abdomen. Unenhanced computed tomography revealed a 9×10×18-cm³ mass that was heterogeneous with central lower density. The patient underwent radical nephrectomy, including lymphadenectomy, without adjuvant therapy. The tumor was composed of spindle-shaped myoid cells with a concentric arrangement and showed immunoreactivity for smooth muscle actin and cluster of differentiation (CD)10, and had a Ki-67 index of <1%; however, staining was negative for CD34, desmin, S-100 protein, cytokeratin, human melanoma black (HMB)-45, B-cell lymphoma (Bcl)-2 and CD99. Routine follow-up revealed no local or distant metastatic signs of reccurrence for 20 months. The present report shows that renal myopericytoma may be a benign tumor, and surgical excision without adjuvant therapy may be the only potentially curative treatment approach.

A case report of an intracaval extrathoracic solitary fibrous tumour

Solitary fibrous tumours are infrequent neoplasms based in the pleura that are predominantly benign with malignant pathology and behaviour described in 10-36% of cases. Extrathoracic solitary fibrous tumours (ESFTs) have been considered separately to their intrathoracic counterparts and comprise a third of all solitary fibrous tumours. The extrathoracic location was identified as an adverse prognostic factor for local recurrence but not for metastatic disease. So far, there have not been any reports of solitary fibrous tumours demonstrating caval infiltration. We present a case of a benign ESFT infiltrating into the perirenal inferior vena cava. Together with extrauterine leiomyomas, ESFTs should also be considered as a differential diagnosis for the rare benign lesions invading the inferior vena cava.

A case report of an intracaval extrathoracic solitary fibrous tumour

Solitary fibrous tumours are infrequent neoplasms based in the pleura that are predominantly benign with malignant pathology and behaviour described in 10-36% of cases. Extrathoracic solitary fibrous tumours (ESFTs) have been considered separately to their intrathoracic counterparts and comprise a third of all solitary fibrous tumours. The extrathoracic location was identified as an adverse prognostic factor for local recurrence but not for metastatic disease. So far, there have not been any reports of solitary fibrous tumours demonstrating caval infiltration. We present a case of a benign ESFT infiltrating into the perirenal inferior vena cava. Together with extrauterine leiomyomas, ESFTs should also be considered as a differential diagnosis for the rare benign lesions invading the inferior vena cava.

Distant metastasis from benign solitary fibrous tumor of the kidney

Solitary fibrous tumor (SFT) rarely occurs in the kidneys, and only one reported case of renal SFT has shown distant metastasis. We report the second case of renal SFT exhibiting distant metastasis. A 48-year-old man was referred to our hospital because of a right renal mass. An abdominal CT scan detected a large renal tumor, which was suspected to be a renal cell carcinoma. Right radical nephrectomy was performed, and the tumor was found to measure 28 × 18 × 10 cm. The pathological diagnosis was benign solitary fibrous tumor of the kidney. Eight years after the operation, lung and liver metastases developed. Pulmonary segmentectomy and partial hepatectomy were performed. The pathological diagnoses of these resected tissue specimens were compatible with benign SFT.

Retroperitoneal solitary fibrous tumor of the pelvis with pollakiuria: a case report

Background

Solitary fibrous tumor (SFT) is rare soft tissue tumor, and it occurs most commonly in the pleura. Retroperitoneal SFT is generally found by palpable mass or abdominal distention. Here we report a case of SFT presenting pollakiuria.

Case presentation

A 64-year-old man was referred to our hospital for pollakiuria. Contrasted-enhanced computed tomography revealed a heterogeneously enhanced pelvic tumor of approximately 10 × 8 × 7 cm. Invasion of the surrounding organs, distal metastasis, and lymph node swelling were absent. Therefore, surgical resection was performed. The resected specimen was a 13 × 8 × 5.5-cm encapsulated elastic hard tumor weighing 420 g. Histologically, the tumor consisted of oval or spindle cells growing in a random manner in a collagenous matrix. Immunohistochemically, the specimen was positive for CD34, bcl-2, as well as vimentin and negative for c-kit. On the basis of these findings, a retroperitoneal solitary fibrous tumor (SFT) of the pelvis was diagnosed.

Conclusion

Surgery is the primary treatment for SFT, and pathologically negative margins are important for good prognosis.

A case of the large retroperitoneal solitary fibrous tumor

A rare autopsy case of the extremely large retroperitoneal solitary fibrous tumor is reported. A 52-year-old female with a huge abdominal distention was found dead at home. She showed remarkable emaciation. The autopsy revealed a huge retroperitoneal tumor weighing 11.9kg (36×30×20cm in size), which occupied the entire intraperitoneal cavity. Histologically, the tumor consisted of spindle parenchymal cells with fibrous tissues. Immunohistochemically, CD34 was positively stained, whereas S-100, smooth muscle actin, and factor VIII were negative. Her cause of death was diagnosed as emaciation due to the compression of the entire intestine by the tumor. This is a rare case of the extremely large retroperitoneal solitary fibrous tumor, which caused the occasional intestinal obstruction. This disease should be considered in the differential diagnosis of retroperitoneal large tumors that cause accidental deaths in forensic autopsies.

Non-islet cell tumor hypoglycemia at the second recurrence of malignant solitary fibrous tumor in the retroperitoneum and pelvis: a case report

An 83-year-old man underwent complete resection of a large malignant solitary fibrous tumor in the retroperitoneum in 2006 and of a local recurrent tumor in 2010. In 2011, he was admitted to our hospital because of hypoglycemia. His serum glucose level was very low, and his levels of insulin and C-peptide were low. Furthermore, he had a recurrent tumor in the retroperitoneum and pelvis. Immediately after the third surgery for complete resection, he had no hypoglycemic episodes and his serum glucose level was within the normal range. Immunoblotting analysis revealed a high-molecular-weight form of insulin-like growth factor II in the patient's serum and in the protein extract obtained from the resected specimen in 2011. To our knowledge, this is the first report of non-islet cell tumor hypoglycemia caused by a malignant solitary fibrous tumor secreting a high-molecular-weight form of insulin-like growth factor II at the second recurrence.

F-18 FDG PET/CT and Tc-99m sulfur colloid SPECT imaging in the diagnosis and treatment of a case of dual solitary fibrous tumors of the retroperitoneum and pancreas

Although FDG PET is increasingly used for the staging of many types of sarcoma, little has been written regarding the FDG PET imaging characteristics of solitary fibrous tumor. We report a patient undergoing FDG PET/CT surveillance for squamous cell carcinoma of the tongue who was incidentally found to have two soft tissue masses in the retroperitoneum and pancreatic tail. Due to their low degree of FDG avidity, they were followed conservatively for approximately one year as they gradually increased in size. Technetium-99m sulfur colloid SPECT helped confirm that the pancreatic tail mass was not a splenule, after which both lesions were surgically resected and found to be extrathoracic solitary fibrous tumors without malignant features. These findings suggest that, as with other low-grade sarcomas, benign extrathoracic solitary fibrous tumors exhibit relatively little glycolytic metabolism in vivo.

Solitary fibrous tumor: an update on the spectrum of extrapleural manifestations

Solitary fibrous tumor (SFT) is a rare tumor initially believed to be a benign localized pleural tumor of mesothelial origin. Over the past few years, the literature on this tumor has grown tremendously. The tumor is now reported in diverse bodily locations, and recognized to have a wider range of clinical and radiological features. The most common extrapleural sites of the tumor are the orbits and the extremities. Tumors are often well-circumscribed masses, and vary in size from 1 cm to over 30 cm. The admixture of histological components in the tumor, namely, fibrous tissue, cellular components, and highly vascularized areas consisting of numerous closely packed small to medium-sized blood vessels, influence the imaging appearances of the tumor. On magnetic resonance imaging (MRI), the diagnosis of solitary fibrous tumor is suggested by a well-circumscribed mass that has smooth margins, and focal or diffuse hypointense signal on T2-weighted imaging due to fibrous content in the tumor. SFTs demonstrate strong focal or diffuse contrast enhancement due to the highly vascularized areas in the tumor.

Primary solitary fibrous tumor of the retroperitoneum

Solitary fibrous tumor is an uncommon neoplasm affecting adults and typically located in the pleura and can also occur in a large number of other extra thoracic sites. We present the case of a solitary fibrous tumor (SFT) of the retroperitoneum and describe their histopathological and immunohistochemical features. The identification of SFT in the retroperitoneum is of importance because its clinico-pathological behaviour is still unclear. The pathologist plays a fundamental role in establishing both the positive and differential diagnosis.

Somatic and visceral solitary fibrous tumors in the abdomen and pelvis: cross-sectional imaging spectrum

Solitary fibrous tumors (SFTs) are a unique group of mesenchymal neoplasms of fibroblastic or myofibroblastic origin. These tumors were originally described as "benign fibrous mesotheliomas" of the pleural cavity and were erroneously thought to be confined to the serosal surfaces (due to a putative mesothelial or submesothelial origin). It is now established that SFTs are ubiquitous neoplasms with both pleural and extrapleural distribution. Extrapleural SFTs commonly occur in middle-aged adults and manifest as asymptomatic, slow-growing, large tumors. Fewer than 5% of patients with SFTs present with symptomatic hypoglycemia. SFTs are histopathologically diverse with a variable admixture of fibroblasts or myofibroblasts, numerous thin-walled vessels, and dense fibrosis. Tumors previously categorized as hemangiopericytomas are now considered cellular variants of SFTs. At imaging, SFTs demonstrate remarkable heterogeneity, with variable degrees of enhancement, necrosis, or hemorrhage. Although most extrapleural SFTs have a benign clinical course, 10%-15% of these tumors demonstrate aggressive behavior in the form of recurrence or malignancy.

Surgical resection using retroperitoneal approach for solitary fibrous tumor in the pelvis

This report concerns a case of solitary fibrous tumor (SFT) for which surgical resection was performed using a retroperitoneal approach. A 41-year-old man was referred to our hospital with urinary retention. Abdominal ultrasound sonography (US) and computed tomography (CT) showed a hypervascular mass lesion in the pelvis. Transrectal biopsy showed SFT. Surgical resection was carried out using a retroperitoneal approach and preserving the neural network related to urinary and erectile functions. Based on immunohistochemical findings, the tumor was diagnosed to be malignant SFT in the pelvic cavity. Urinary function improved post-operation. There was no change to IIEF-5 and it continued to function well. The patient showed no sign of recurrence 12 months after surgery and required no additional therapy.

Retroperitoneal solitary fibrous tumor-induced hypoglycemia associated with high molecular weight insulin-like growth factor II

A man, aged 65 years, presented with frequent episodes of hypoglycemia and unconsciousness. Hypoglycemia was accompanied by undetectable serum insulin and C-peptide levels and a high serum insulin-like growth factor (IGF)-II level. He was found to have a retroperitoneal solitary fibrous tumor. He underwent successful resection of the tumor and had no hypoglycemic episodes after the operation. Immunohistochemical analysis revealed positive immunostaining for IGF-II in tumor cells. The presence of the high-molecular-weight form of IGF-II in the patient's serum was confirmed by immunoblotting, which suggests that his hypoglycemia was due to an increase in the plasma level of IGF-II secreted by the tumor.

Gastrointestinal Stromal Tumors: A Guide to the Diagnosis

Gastrointestinal stromal tumors (GISTs) have emerged from being a poorly understood and therapeutically refractory sarcoma to a tumor whose biology has not only provided insight into a mechanism of oncogenesis but has also led to a rational basis for therapy. Most GISTs are characterized by KIT protein (CD117) expression and constitutive activating mutations in either the c-kit or platelet-derived growth factor receptor α genes. This information can now be obtained from routine formalin-fixed and paraffin-embedded tissue. Because the correct diagnosis is the key to successful treatment of this tumor, it is incumbent on the pathologist to be familiar with the various gross and histologic patterns shown by these tumors. GISTs range from small incidental stromal nodules to large cystic and solid tumor masses. GISTs show a variety of microscopic patterns and therefore several other tumors enter the differential diagnosis. Fortunately, with an understanding of GIST histology, and with the proper use of immunohistochemistry and molecular analysis, a correct diagnosis can usually be made. In addition to the correct diagnosis, several key attributes of the tumor need to be determined because they provide the basis for proper clinical management. This article summarizes the gross, microscopic, and molecular findings of GISTs, and discusses the differential diagnosis and key attributes of this interesting group of neoplasms.