Imaging features of solitary fibrous tumors. AJR Am J Roentgenol. 2011;196:487-495. [PMID: 21343490 DOI: 10.2214/ajr.10.4948]

Solitary fibrous tumors from A to Z: a pictorial review with radiologic-pathologic correlation

Solitary fibrous tumors (SFTs) represent a rare subset of mesenchymal neoplasms, affecting 1-2 per million people, with no gender preference. They demonstrate indolent behavior, frequent asymptomatic presentation, and widespread anatomical involvement. At imaging, SFTs typically appear as well-defined, predominantly hypervascular masses with varying degrees of cystic change and necrosis, though calcification is rare. Avid heterogeneous enhancement is typical following intravenous contrast administration, with multiple blood vessels observed at the periphery. Although findings on CT and MRI alone are generally nonspecific, a frequent feature of SFTs at MRI is the presence of rounded or linear low signal intensity foci on T1- and T2-weighted images, corresponding to the fibrous and collagenous content. Nevertheless, because the imaging features of SFTs overlap with those of many benign and malignant tumors, histologic confirmation is required for the final diagnosis. A comprehensive understanding of SFTs' multifaceted clinical, pathological, and radiological presentations across various organs is crucial for accurate diagnosis and effective management. CRITICAL RELEVANCE STATEMENT: A comprehensive understanding of the classic radiological and pathological features of solitary fibrous tumors across various organs is crucial for accurate diagnosis and effective management. KEY POINTS: Solitary fibrous tumors (SFTs) are rare hypervascular fibrous tumors with indolent behavior. Imaging features of SFTs overlap with many other tumors, necessitating histologic confirmation. Understanding SFTs' radiological presentations is crucial for accurate diagnosis and effective management.

Solitary fibrous tumor in the pterygopalatine fossa: a rare case report and literature review

INTRODUCTION

Solitary fibrous tumor is a rare spindle cell tumor that may occur in various parts of the body. No documented case of solitary fibrous tumor has been reported in pterygopalatine fossa.

CASE REPORT

A 25-year-old male complained of right facial numbness for 20 days. Computed tomography of the paranasal sinuses demonstrated a well-circumscribed lesion centered in the right pterygopalatine fossa. On magnetic resonance imaging the lesion was homogenously isointense to muscle on T1 weighted imaging (T1WI) and slightly hyperintense to muscle on T2 weighted (T2WI). The intro-operative frozen pathology reveals a benign spindle cell tumor. The tumor was removed successfully via transnasal combined with Caldwell-Luc approach without complications. However, the final pathology combined with immunohistochemistry confirmed the diagnosis of solitary fibrous tumor. No further radiotherapy is performed post-operation. After half a year follow up, there is no recurrence.

CONCLUSION

For the tumor in the pterygopalatine fossa, the possibility of solitary fibrous tumor should be considered and radical endoscopic resection should be the preferred treatment approach.

Malignant solitary fibrous tumor in the anterior abdominal wall: a rare case report with diagnostic and therapeutic insights

Solitary fibrous tumors (SFTs) are rare mesenchymal tumors, most commonly occurring in the pleura. Extrapleural cases, particularly in the anterior abdominal wall, are extremely rare. We present a rare case of a malignant SFT arising from the left anterior abdominal wall in an adult patient in their 60s, who presented with a mass in left iliac fossa. The diagnosis was confirmed by tissue biopsy and immunohistochemical analysis. The presented case highlights the rarity of malignant SFTs in the anterior abdominal wall, emphasizing the importance of thorough diagnostic evaluation and surgical management for optimal outcomes.

Unexpected outcomes of tislelizumab treatment in thoracic metastasis of malignant phyllodes tumors: a case report and literature review

Phyllodes tumo (PT) of the breast are classified into benign, borderline, and malignant types. Malignant phyllodes tumor (MPT) with metastasis, particularly those containing sarcomatous components, have a notably poor prognosis. The most common sites of metastasis are the lungs, although metastases can also occur in the pleura and other areas. Metastatic PT is typically treated according to NCCN guidelines for soft tissue sarcomas. The prognosis for patients is extremely poor, with survival typically not exceeding five years. Therefore, the treatment of metastatic MPT presents significant challenges. A 67-year-old female with a history of PT surgery was hospitalized due to acute chest tightness and shortness of breath. MRI revealed a large mass in the left thoracic region, measuring 7.9 × 10.8 × 11.4 cm. A biopsy conducted prior to hospitalization indicated spindle cell soft tissue sarcoma. Due to critical vital signs, she underwent an emergency thoracotomy. Postoperative analysis confirmed the diagnosis of thoracic metastasis from MPT with sarcomatous components. Genetic analysis of the tumor tissue post-surgery revealed a KDM6A gene mutation. Unfortunately, subsequent imaging showed a recurring mass in the left thoracic space, approximately 8 cm in size. Considering the side effects of NCCN-recommended treatments (doxorubicin and ifosfamide) and the high cost of targeted therapies, the patient and her family chose tislelizumab. After six cycles of treatment, the patient's progression-free survival reached 15 weeks. Due to unsatisfactory treatment effects, the patient and her family decided to discontinue therapy, and the patient passed away in July 2024. Although the combination of surgery and postoperative immune checkpoint inhibitors remains to be validated, this case provides valuable insights into the management of thoracic metastasis from MPT. It offers potential new options for personalized immunotherapy in metastatic MPT.

Thoracic Intradural Extramedullary Cavernous Malformation Mimicking Meningioma

Cavernous malformation, also known as cavernoma or cavernous hemangioma, is a benign vascular malformation characterized by abnormal proliferation of capillaries that lack intervening neural tissue. Spinal intradural extramedullary cavernous malformations are exceedingly rare and, therefore, are often misdiagnosed. Here, we report a rare case of thoracic intradural extramedullary cavernous malformation that mimicked meningioma on preoperative imaging. A 77-year-old male patient presented with a two-month history of myelopathy, progressive paresthesia in the lower extremities, and difficulty walking, noted during an outpatient clinic visit. Spinal magnetic resonance imaging detected an intradural extramedullary mass lesion on the dorsal side at the Thoracic (Th) 10 vertebral level, compressing the thoracic cord. Preoperative imaging revealed a uniform T1- and T2-weighted intensity signal, suggesting meningioma. Intraoperatively, the mass appeared reddish with multiple abnormal vessels and adhered firmly to the thoracic cord. The lesion was completely resected, and postoperative pathological examination confirmed the diagnosis of cavernous malformation. The patient's preoperative symptoms improved postoperatively. Thoracic intradural extramedullary cavernous malformations are extremely rare and typically present with heterogeneous intensity signals on magnetic resonance imaging. Additionally, they can cause subarachnoid hemorrhage, emphasizing the importance of considering them in the preoperative differential diagnosis, even though imaging characteristics may be atypical. Surgical gross total resection should be considered to prevent future hemorrhage and neurological deterioration.

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

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

Cinematic rendering of pleural solitary fibrous tumor

Solitary fibrous tumors are rare and typically benign fibroblastic neoplasms with a mean age of onset ranging from 60 to 70 years. Solitary fibrous tumors may arise anywhere within the body, however the pleura is the most common site of origin for these tumors, with approximately 30% of tumors arising from the pleura. In this report we highlight the case of a 62-year-old woman who presented with gradually progressive left sided chest pain that was eventually diagnosed as a pleural SFT. We highlight the appearance of solitary fibrous tumor of the pleura on computed tomography and positron emission tomography imaging, as well as providing detailed cinematic rendering images of these rare neoplasms.

Solitary fibrous tumors: radiologic features with clinical and histopathologic correlation

Objective

Solitary fibrous tumor (SFT) is an uncommon mesenchymal neoplasm that exhibits a broad spectrum of biological behaviors. Few studies relative to clinical-pathologic features and radiologic manifestations of SFTs have been reported. This study aimed to correlate the radiologic findings of SFTs with the clinical and histopathologic features.

Methods

The clinical, surgical, and histopathologic records; and CT or MR images in 38 pathologically proved cases of SFTs were retrospectively evaluated.

Results

All tumors were seen as oval (n=18) or irregular (n=20), well-defined (n=36) or ill-defined (n=2) masses with a mean size of 11.0 cm. On CT images, most tumors showed a heterogeneous density on precontrast image, and the mean density of the tumor parenchyma was 40.7 hounsfield units. Intratumoral calcification was seen in 6 tumors. After contrast media administration, most tumors showed moderate to marked enhancement (n=34). Multiple intratumoral vessels were seen in 23 tumors. Collateral feeding vessels were seen in 19 tumors. On MR images, all 6 tumors showed a low signal intensity on T1 weighted images and high signal intensity with separate foci of hypointensity on T2 weighted images, as well as significantly imhomogeneous enhancement after contrast administration.

Conclusion

The presence of a large, well-defined, highly vascular soft tissue tumor with map-like enhancement and prominent collateral feeding vessels should alert the radiologist to the possible diagnosis of SFT. Diagnostic imaging coupled with clinicopathologic analysis allows accurate localization, identification, and resection of SFTs.

A Rare Case of Solitary Fibrous Tumor of the Breast in a Healthy 40-Year-Old Woman

Solitary fibrous tumor (SFT) is a rare neoplasm of mesenchymal origin that is primarily found in the lungs but can be found in other locations such as the retroperitoneum, deep soft tissues of the proximal extremities, abdominal cavity, head, and neck. Moreover, SFTs found in the breast are extremely rare and, oftentimes, are found incidentally during screening mammography. Our case presents an exceptionally rare occurrence of a SFT in the breast of a 40-year-old woman. This rarity is underscored by its classification as a SFT and its unusual location within the breast tissue as well as this patient's young age. This case emphasizes the importance of a thorough evaluation with both imaging and histopathology for diagnosing SFTs. It also addresses the potential difficulties that may arise during this process, especially for radiologists who may have limited experience encountering SFTs.

MRI Characteristics for Distinguishing Solitary Fibrous Tumor From Desmoid Tumor

OBJECTIVE

To elucidate the magnetic resonance imaging (MRI) characteristics for distinguishing solitary fibrous tumors (SFTs) from desmoid tumors (DTs).

MATERIALS AND METHODS

A retrospective study of 66 consecutive patients with histopathologically proven SFT (n = 34; 13 males and 21 females; mean age, 52.0 ± 17.1 years) or DT (n = 32; 11 males and 21 females; mean age, 39.0 ± 21.3 years) was conducted. The two groups were quantitatively compared in terms of the size, signal intensity ratio (SIR), and apparent diffusion coefficient value. For qualitative analysis, the tumor location, boundary, shape, internal uniformity, predominant signal intensity, T1-weighted images (T1WI) characteristics (hyperintense area), T2-weighted images (T2WI) characteristics (hypointense area, marked hyperintense area, flow void, band sign, and yin-yang sign), and contrast-enhanced T1WI characteristics (unenhanced area and degree of enhancement) were compared between the two groups. Multiple stepwise logistic regression analyses were conducted to distinguish between the SFT and DT.

RESULTS

T1 (P = 0.010) and T2 (P = 0.026) SIRs were higher in SFTs than in DTs. Hyperintense areas on T1WI (P < 0.001), marked hyperintense areas on T2WI (P = 0.025), and flow void (P = 0.025) were more frequently noted in SFTs. On T1WI, the solid component predominantly revealed hyperintensity in SFTs and isointensity in DTs (P < 0.001). Indistinct tumor boundary (P < 0.001), hypointense area on T2WI (P < 0.001), and band sign (P < 0.001) were more frequently observed in DTs. Multiple stepwise logistic regression analysis revealed that the hyperintense area on T1WI (odds ratio favoring SFT, 12.80, P = 0.002) and band sign (odds ratio favoring DT, 0.03; P < 0.001) were independent predictors.

CONCLUSION

MRI characteristics can help distinguish SFT from DT. The presence of a hyperintense area relative to the skeletal muscle on T1WI in SFTs and the band sign on T2WI in DTs are important MRI features.

Case report: A rare case of malignant solitary fibrous tumor within the joint cavity with review of the literature

Solitary fibrous tumors (SFTs) are classified as fibroblastic/myofibroblastic tumors that originate from CD34-positive dendritic cells and usually occur in the pleura. In this paper, we describe a case of SFT within the joint cavity of the left knee. A 60-year-old man was admitted to hospital due to swelling in the left knee for the past 8 months without relevant trauma history. X-ray, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography-computed tomography (PET-CT) presented a large, ill-circumscribed, hypervascular, and highly enhanced mass with eccentric calcification and peripheral, intra-lesional vessels. Subsequently, the patient underwent surgical resection. Postoperative pathology confirmed the neoplastic cells to be positive for CD34, Bcl-2, and SATA6, therefore was finally diagnosed as malignant SFT. The patient developed bone metastases within 1 year after surgery. SFT in the joint cavity is rare, and it is difficult to make a preoperative diagnosis.

Solitary fibrous tumor of the gallbladder: a case report

BACKGROUND

Primary solitary fibrous tumors (SFTs) of the gallbladder are rare. Here, we report the case of a patient who underwent surgical treatment for a primary SFT originating in the gallbladder.

CASE PRESENTATION

A 48-mm gallbladder tumor was detected in a 70-year-old man using abdominal ultrasonography at a primary hospital, and he was subsequently referred to our department. A 50-mm enhanced tumor in the gallbladder was identified using computed tomography. Magnetic resonance imaging revealed a smooth-marginated tumor with hyperintensity on T2-weighted imaging. 18F-Fluorodeoxyglucose positron emission tomography confirmed high-level fluorodeoxyglucose uptake in the gallbladder tumor in the early phase without increasing uptake in the later phase. Surgical resection was planned to evaluate the tumor diagnosis. Initially, we performed open cholecystectomy with wedge resection of the gallbladder bed. Intraoperative pathological examination suggested gallbladder cancer; therefore, we performed radical surgery, including resection of the common bile duct, extended radical lymphadenectomy, and choledochojejunostomy. Ultimately, the final pathological examination revealed an SFT originating from the gallbladder with a negative surgical margin. Postoperatively, the patient developed bile leakage that was treated with tube drainage. The patient recovered satisfactorily and was discharged on postoperative day 20. At 24 months postoperatively, the patient was in good general condition without recurrence.

CONCLUSIONS

We report a rare case of a primary SFT originating in the gallbladder. Clinicians should be aware that SFT can be found in the gallbladder, and when it is difficult to make a preoperative diagnosis, surgical treatment should be considered.

Case Report: Successful Treatment of Solitary Fibrous Tumor with Selective Internal Radiation Therapy (SIRT)

Background: This case report details the innovative use of selective internal radiation therapy (SIRT) with Yttrium-90 resin microspheres to treat a 73-year-old woman with a solitary fibrous tumor (SFT), a rare and challenging tumor type. SFTs often present significant treatment difficulties, especially in cases of recurrence or metastasis, as systemic therapies typically show limited effectiveness. This report explores SIRT as an alternative therapeutic approach for SFTs with liver metastasis. Methods: The patient initially presented with a pelvic mass, which was surgically resected. However, metastatic disease later developed in the liver. After experiencing severe side effects from targeted therapy with sunitinib, the patient was selected for treatment with SIRT as an alternative. Results: Following the SIRT intervention, the patient demonstrated a substantial reduction in tumor size and significant relief from symptoms. This outcome suggests SIRT's effectiveness as a targeted treatment for metastatic SFT. Conclusions: To our knowledge, and based on an extensive literature review, this is the first reported instance of treating SFT with SIRT. This case provides new insights into SIRT's potential as a therapeutic strategy, particularly for patients for whom conventional treatments are either ineffective or intolerable. The success observed here underscores SIRT's potential as a less invasive, locally targeted treatment option, offering hope for similar cases.

Prognostic significance of collagen content in solitary fibrous tumors of the central nervous system

Purpose

We aimed to explore the prognostic significance of collagen content in solitary fibrous tumors (SFTs) of the central nervous system (CNS) and preliminarily investigate its relationship with magnetic resonance imaging (MRI) features of SFTs.

Methods

Collagen content was identified using Masson's trichrome staining, and quantitatively assessed. Radiomic methods were applied to extract quantitative MRI features of SFTs, which were then analyzed in relation to collagen content.

Results

The collagen content in CNS SFTs was categorized into high- and low-content groups, with a cutoff value of 6%. Survival analysis indicated a positive correlation between collagen content and overall survival (OS). In multivariate Cox regression analysis, incorporating factors such as mitosis, necrosis, Ki67, and collagen content and other indicators, collagen content emerged as an independent prognostic factor. Collagen content demonstrated a negative correlation with tumor histological phenotype, Ki67, WHO grade, mitosis, necrosis, and brain invasion. Additionally, the signal intensity of SFTs on T2-weighted imaging (T2WI) decreased with increasing collagen content. Radiomics analysis identified 1,702 features from each patient's region of interest, with 12 features showing significant differences between the high and low collagen content groups. Among the quantitative parameters and radiomic models, the combined T1- and T2WI models exhibited the highest diagnostic performance.

Conclusion

These findings suggest that collagen content is an independent prognostic risk factor for OS. Furthermore, combined radiomic models based on T1-and T2WI sequences may offer a more comprehensive, objective, and accurate assessment of collagen content in CNS SFTs.

Ruptured solitary fibrous tumor of the pleura with hemothorax: a case report

BACKGROUND

The majority of the patients with a solitary fibrous tumor (SFT) of the pleura are asymptomatic, and rupture of an SFT with hemothorax is rare.

CASE PRESENTATION

A 48-year-old man was taken by ambulance to our hospital because of sudden onset of left chest pain. Two months before the referral, a tumor was detected in the left upper lobe of the lung by screening computed tomography at another hospital, and further observation was recommended, because the tumor was suspected to be benign. Our contrast-enhanced computed tomography analysis of the chest revealed a solid tumor (5 cm in diameter) with an irregular enhancement effect close to the pericardium and pleural effusion in the left thoracic cavity. Pleural effusion was not detected in the previous imaging analysis. CT number of the pleural effusion was 40 HU, and the pleural effusion was suspected to be hematogenous. Therefore, rupture of the tumor with bleeding was suspected as the cause of the effusion because of the sudden onset. Preoperative diagnosis was a mediastinal tumor, such as a teratoma, because the tumor was close to the pericardium. Thoracoscopic surgery was performed with the patient in the right lateral decubitus position; bloody pleural effusion was observed and drained. The tumor originated from the visceral pleura of the left upper lobe of the lung and was resected with a surgical stapler. Macroscopic analyses of the resected tumor indicated that bleeding were caused by the rupture of the tumor at the defect of the capsule wall. The operation took 63 min. The postoperative pathological diagnosis was a benign SFT. Hemorrhage was observed just under the capsule wall of the tumor. The postoperative course of the patient was uneventful, and he was discharged 2 days after surgery.

CONCLUSIONS

Even when an SFT is neither huge nor malignant, rupture can occur, and resection should be considered regardless of the size or malignant characteristics. After an SFT rupture, careful follow-up is needed to monitor for the intrathoracic recurrence or dissemination of the tumor.

Unsuccessful laparoscopic resection of a large pelvic solitary fibrous tumor: A case report

We present a rare case of a female pelvic solitary fibrous tumor unsuccessfully resected using single-port laparoscopy, requiring conversion to laparotomy. Although the resection was successful, the surgical approach could have been improved. For large tumors, minimally invasive results are possible with flexible choices of equipment and incision position.

Imaging Findings of Solitary Fibrous Tumors of the Gallbladder

Solitary Fibrous Tumor (SFT) is a rare mesenchymal tumor with a higher incidence of benign than malignant, most common location in the pleura. Although this tumor has been found in other locations in the body such as the head and neck region, retroperitoneal space, and intra-abdominal omentum, SFT of the gallbladder remains extremely rare in the medical literature. In this article, we present the imaging characteristics of Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) of gallbladder SFT, thereby contributing to providing information in the study of this rare pathology.

A Rare Case of Chest Wall Castleman's Disease with Calcification

Castleman's disease with calcification of the chest wall is very rare, and there have been few reports of such cases to date. A 57-year-old woman was referred to our hospital for a tumor with calcification on her left lateral chest wall, which was detected on chest computed tomography. Findings of her chest magnetic resonance imaging suggested schwannoma or a solitary fibrous tumor, and therefore, we performed surgery for diagnostic and therapeutic purposes. Pathologically, the tumor with calcification was diagnosed as Castleman's disease of the hyaline-vascular type. After the surgery, the patient has had no obvious symptoms and continues to undergo regular follow-up examinations.

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.

Surgical Treatment of the Solitary Fibrous Tumour/ Haemangiopericytoma of the External Auditory Canal: A Case Report

A solitary fibrous tumour (SFT)/haemangiopericytoma (HPC) accounts for approximately 1% of all vascular tumours, and 13-25% of them are present in the head and neck region. Here, a case of SFT in the left EAC has been reported with the longest duration follow-up among the previously reported cases.

Locally advanced solitary fibrous tumour of the prostate

Solitary fibrous tumours (SFTs) are rare mesenchymal neoplasms composed of spindle cells, most often occurring in the pleura. SFTs arising from the prostate are exceptionally rare, with only around 40 cases reported in literature to date. We report a man in his 60s who was referred to our clinic for elevated prostate-specific antigen and presented with mild obstructive lower urinary tract and defecatory symptoms. Prostate needle-core biopsy revealed neoplastic spindle cells that strongly expressed CD34. Cross-sectional imaging demonstrated a 12 cm locally advanced heterogeneous prostate mass with intravesical extension and mass effect on the anterior rectum. Radical cystoprostatectomy with orthotopic neobladder reconstruction was performed, and the diagnosis of primary prostatic SFT was made based on histological characteristics and immunophenotyping. We present diagnostic, clinical management and prognostic considerations in patients with primary prostatic SFT.

Cross-sectional imaging review of common to uncommon lung cancer mimickers in a tertiary care oncology center

Lung cancer is the most diagnosed cancer worldwide. Many non-malignant pulmonary lesions, such as tuberculosis, fungal infection, organizing pneumonia, inflammatory myofibroblastic tumor, and IgG4 disease, can mimic lung cancer due to their overlapping morphological appearance on imaging. These benign entities with minor differentiating imaging clues may go unnoticed in a high-volume cancer institution, leading to over-investigation that may result in repeated biopsies, pointless wedge resections, and related morbidities. However, with a thorough medical history, laboratory diagnostic work-up, and careful analysis of imaging findings, one can occasionally restrict the range of possible diagnoses or arrive at a definitive conclusion. When imaging features overlap, image-guided lung sampling is crucial since histopathological analysis is the gold standard.

A case report of solitary fibrous tumor of the thyroid gland and literature review

RATIONALE

A solitary fibrous tumor (SFT) is an uncommon soft tissue tumor that was first discovered in the pleura. Although SFTs have been documented in other extra-pleural sites, an SFT in the thyroid gland is highly unusual. An SFT of the thyroid gland can be difficult to diagnose, and there is little information about their Underlying biological behavior.

PATIENT CONCERNS

We present a case of a 63-year-old man with a progressively growing left-neck mass detected 1 month ago, which was pathologically confirmed to be a benign SFT of the thyroid gland.

DIAGNOSIS

Postoperative pathological examination of the tumor revealed an SFT. Immunopathological examination was consistent with the diagnosis of an SFT.

INTERVENTIONS

The patient underwent surgical resection of the SFT.

OUTCOMES

The patient was recurrence-free during 1.5 years of follow-up.

LESSONS

Surgical excision is beneficial in SFTs that show no histological signs of malignancy, such as pleomorphism, enhanced mitotic activity, necrosis, bleeding, or capsular invasion. However, because the biologic activity remains unknown, meticulous long-term monitoring is required.

Rare Solid Pancreatic Lesions on Cross-Sectional Imaging

Several solid lesions can be found within the pancreas mainly arising from the exocrine and endocrine pancreatic tissue. Among all pancreatic malignancies, the most common subtype is pancreatic ductal adenocarcinoma (PDAC), to a point that pancreatic cancer and PDAC are used interchangeably. But, in addition to PDAC, and to the other most common and well-known solid lesions, either related to benign conditions, such as pancreatitis, or not so benign, such as pancreatic neuroendocrine neoplasms (pNENs), there are solid pancreatic lesions considered rare due to their low incidence. These lesions may originate from a cell line with a differentiation other than exocrine/endocrine, such as from the nerve sheath as for pancreatic schwannoma or from mesenchymal cells as for solitary fibrous tumour. These rare solid pancreatic lesions may show a behaviour that ranges in a benign to highly aggressive malignant spectrum. This review includes cases of an intrapancreatic accessory spleen, pancreatic tuberculosis, solid serous cystadenoma, solid pseudopapillary tumour, pancreatic schwannoma, purely intraductal neuroendocrine tumour, pancreatic fibrous solitary tumour, acinar cell carcinoma, undifferentiated carcinoma with osteoclastic-like giant cells, adenosquamous carcinoma, colloid carcinoma of the pancreas, primary leiomyosarcoma of the pancreas, primary and secondary pancreatic lymphoma and metastases within the pancreas. Therefore, it is important to determine the correct diagnosis to ensure optimal patient management. Because of their rarity, their existence is less well known and, when depicted, in most cases incidentally, the correct diagnosis remains challenging. However, there are some typical imaging features present on cross-sectional imaging modalities that, taken into account with the clinical and biological context, contribute substantially to achieve the correct diagnosis.

Fibroblastic and Myofibroblastic Soft-Tissue Tumors: Imaging Spectrum and Radiologic-Pathologic Correlation

Fibroblastic and myofibroblastic tumors are a variable group of neoplasms ranging from benign to malignant. These lesions may affect patients of any age group but are more frequently encountered in the pediatric population. Patient clinical presentation depends on the location, growth pattern, adjacent soft-tissue involvement, and pathologic behavior of these neoplasms. In the 2020 update to the World Health Organization (WHO) classification system, these tumors are classified on the basis of their distinct biologic behavior, histomorphologic characteristics, and molecular profiles into four tumor categories: (a) benign (eg, fibrous hamartoma of infancy, nodular fasciitis, proliferative fasciitis, fibroma of the tendon sheath, calcifying aponeurotic fibroma); (b) intermediate, locally aggressive (eg, desmoid fibromatosis); (c) intermediate, rarely metastasizing (eg, dermatofibrosarcoma protuberans, myxoinflammatory fibroblastic sarcoma, low-grade myofibroblastic sarcoma, infantile fibrosarcoma); and (d) malignant (eg, sclerosing epithelioid fibrosarcomas; low-grade fibromyxoid sarcoma; myxofibrosarcoma; fibrosarcoma, not otherwise specified). Detection of various components of solid tumors at imaging can help in prediction of the presence of corresponding histopathologic variations, thus influencing diagnosis, prognosis, and treatment planning. For example, lesions with a greater myxoid matrix or necrotic components tend to show higher signal intensity on T2-weighted MR images, whereas lesions with hypercellularity and dense internal collagen content display low signal intensity. In addition, understanding the radiologic-pathologic correlation of soft-tissue tumors can help to increase the accuracy of percutaneous biopsy and allow unnecessary interventions to be avoided. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Intradural Extramedullary Tumors and Associated Syndromes

Most intradural tumors are located within the intradural extramedullary compartment, and the most common tumors are schwannomas and meningiomas. Other less common neoplasms include neurofibroma, solitary fibrous tumor, myxopapillary ependymoma, lymphoma, metastatic leptomeningeal disease, malignant peripheral nerve sheath tumor, and paraganglioma. Patients usually present with gait ataxia, radicular pain, and motor and sensory deficits due to chronic compressive myelopathy or radiculopathy. MRI is the modality of choice for detecting and evaluating intradural extramedullary spinal tumors. This imaging technique helps narrow the differential diagnosis and therefore decide treatment.

A Large Pleural Solitary Fibrous Tumor Successfully Resected Using Uniportal Video-Assisted Thoracoscopic Surgery

Solitary fibrous tumors (SFTs) are rare neoplasms arising from submesothelial connective tissue. Typically affecting elderly individuals, SFTs can exhibit malignant characteristics despite most cases being benign. Diagnosis often occurs incidentally on routine chest radiographs, and patients are usually asymptomatic unless the tumor causes compression of adjacent structures. While imaging studies aid in identification, confirmation of the diagnosis requires bronchoscopy with tissue sampling and immunohistochemistry. Surgical excision remains the primary treatment for SFTs, with complete resection being associated with a better prognosis. Our case highlights the successful management of a massive SFT using uniportal video-assisted thoracoscopic surgery (VATS). Regular chest computed tomography (CT) follow-up is important for monitoring SFTs and ensuring timely intervention when necessary. We present the case of a 54-year-old female with a massive SFT presenting as a pleural tumor in the right lower lobe. The patient was initially asymptomatic, and the diagnosis was made incidentally during routine chest CT follow-up. Uniportal VATS was successfully performed for the excision of the tumor measuring 10x9x6 cm. Our case highlights the successful application of uniportal VATS for the thoracoscopic removal of a huge pleural solitary fibrous tumor.

Pleural Neoplasms-What Could MRI Change?

The primary pleural neoplasms constitute around 10% of the pleural tumors. The currently recommended method for their imaging is CT which has been shown to have certain limitations. Strong development of the MRI within the last two decades has provided us with a number of sequences that could potentially be superior to CT when it comes to the pleural malignancies' detection and characterization. This literature review discusses the possible applications of the MRI as a diagnostic tool in patients with pleural neoplasms. Although selected MRI techniques have been shown to have a number of advantages over CT, further research is required in order to confirm the obtained results, broaden our knowledge on the topic, and pinpoint the sequences most optimal for pleural imaging, as well as the best methods for reading and analysis of the obtained data.

A case report and literature review on primary solitary fibrous tumor of the bladder

RATIONALE

Solitary fibrous tumors (SFT) is a rare mesenchymal tumor originating from a CD34-positive dendritic mesenchymal cell, most of which is benign, the most common sites is pleura and mediastinum, and rarely in the bladder. The clinical manifestations are mainly related to the tumor volume. When the tumor volume is large, it will compress the surrounding tissues or organs and cause corresponding symptoms. Laparoscopic Incision biopsy is effective means for diagnosing SFT.

PATIENT CONCERNS

A 70-year-old female patient was admitted to the hospital with a bladder neoplasm detected by computed tomography scan after experiencing intestinal obstruction 3 days following esophageal cancer surgery. She denied any history of tumor disease.

DIAGNOSES

No abnormality was found in the physical examination and laboratory testing after admission. Ultrasound imaging showed a large solid mass with low echogenicity in the bladder. Urological computed tomography with 3D reconstruction revealed a large cystic-solid mass located on the right wall of the bladder, measuring approximately 6.8 cm × 7.1 cm × 6.5 cm, with uneven density and mild inhomogeneous enhancement after contrast administration. Cystoscopy revealed a large mucosal bulge on the right wall of the bladder and laparoscopic exploration revealed a smooth-surfaced round mass, approximately 7 cm in size.

INTERVENTIONS

Incision biopsy was performed to make a clear diagnosis, and appropriate tissue specimens were obtained for pathological testing.

OUTCOMES

The patient was diagnosed as SFT according to pathology. The patient was followed up for 6 months after surgery, and no recurrence was observed.

LESSONS

SFT occurring in the bladder are extremely rare, and the site is scarcely reported in the relevant literature; thus, it is easy to misdiagnose and laparoscopic incision biopsy may be a good choice.

A Rare Case of Solitary Fibrous Tumor of Maxilla: Findings on F-18 FDG and Ga-68 DOTANOC PET-CT

Solitary fibrous tumor (SFT) is a rare tumor of mesenchymal origin that most commonly involves the pleura but can be found anywhere in the body. SFT can range from indolent benign tumors to aggressive malignant tumors, and pre-operative diagnosis is based mainly on imaging. In this case report, we describe an extremely rare case of SFT of left maxilla on F-18 FDG PET-CT and Ga-68 DOTANOC PET-CT. Very few cases of PET-CT findings in SFT are reported in literature; and to our knowledge, none involving the maxilla. By highlighting the findings on F-18 FDG and GA-68 DOTANOC PET-CT, we aim to further add on to the role of both the tracers in the diagnosis and management of this tumor group.

Musculoskeletal Soft-tissue Masses

Evaluation of soft-tissue masses has become a common clinical practice indication for imaging with both ultrasound and MR imaging. We illustrate the ultrasonography and MR imaging appearances of soft-tissue masses based on the various categories, updates, and reclassifications of the 2020 World Health Organization classification.

Imaging Approach to Disease of the Pleura

Diseases of pleura are not only common but also have a significant impact on patients' outcomes. While early detection and treatment are imperative in reducing this burden, many pleural entities present similarly, thus posing a diagnostic dilemma for radiologists requiring critical further workup. While chest radiography, CT, and image-guided thoracentesis are primarily utilized as the initial imaging techniques for the workup of pleural diseases, MRI, and FDG-PET/CT are also frequently employed to investigate the root cause of pleural abnormalities. By elucidating the common imaging features of neoplastic, inflammatory, and infectious pleural pathologies, clinicians can quickly and easily differentiate the various pleural diseases, rapidly reach the correct diagnosis, and ultimately improve patient outcomes.

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 Tumor of the Spine: Imaging Grading Diagnosis and Prognosis

OBJECTIVE

This study aimed to investigate the imaging features and prognosis of spinal solitary fibrous tumors (SFTs) of different pathological grades.

METHODS

The clinical features, computed tomography and magnetic resonance (MR) images, and follow-up data of 23 patients with SFTs were reviewed. The patients were divided into 3 groups according to their pathological manifestations: grade 1 (n = 3), grade 2 (n = 14), and grade 3 (n = 6). The following imaging features were recorded: location, computed tomography density/MR intensity, enhancement pattern, dural tail sign, adjacent bone remodeling, lobulation, and tumor size. The immunohistochemical (Ki-67/MIB-1) levels were also investigated. All parameters were statistically analyzed between grade 2 and 3 tumors.

RESULTS

The Ki-67/MIB-1 index was markedly higher in grade 3 tumors than in grade 2 tumors (P < 0.001). All grade 1 lesions appeared hypointense on T2-weighted image, whereas grade 2 and 3 lesions appeared isointense or mildly hyperintense. There were significant differences in enhancement type and osteolytic bony destruction between grade 2 and 3 tumors (P < 0.05). However, no marked differences were found in the distribution of age, sex, location, MR signal, degree of enhancement, compressive bony absorption, dural tail sign, or maximum vertical/traverse diameter ratio. Malignant progression occurred less frequently in patients with grade 2 tumors than in those with grade 3 tumors, but the difference was not statistically significant.

CONCLUSIONS

Different grades of spinal SFTs have different degrees of proliferation and imaging features, especially grade 3 tumors, which show a heterogeneous enhancement pattern, osteolytic bony destruction, and a higher possibility of recurrence and metastasis.

Soft tissue solitary fibrous tumors of the musculoskeletal system: spectrum of MRI appearances and characteristic imaging features

OBJECTIVE

Solitary fibrous tumors (SFTs) uncommonly occur in the musculoskeletal system, with limited available data on their MRI appearance. This study was performed to assess the MRI features of SFTs in the musculoskeletal system (MSK-SFTs).

MATERIALS AND METHODS

Pre-treatment MRI in 39 patients with pathologically proven SFTs in the trunk or extremities was evaluated. Patient demographics, clinical management and follow-up, and lesion histology were reviewed. MRI features including lesion location, size, morphology, signal characteristics, vascularity, and relationship to major neurovascular structures were assessed.

RESULTS

MSK-SFTs most frequently occurred in the lower extremity (23/39 cases, 59%), deep to fascia (29/39, 74%), and intermuscular (22/29, 76%) in location. The majority of deep lesions were located along a major neurovascular bundle (20/29, 69%). Lesions had well-defined margins (39/39, 100%), multilobulated contours (27/39, 69%), and measured mean 6.9 ± 2.8 cm. The majority of lesions had slightly hyperintense T1 signal (34/39, 87%) and heterogenous intermediate-to-high T2/STIR signal (28/38, 74%). A "pseudo-cerebriform" internal architectural pattern on fluid-sensitive sequences, with internal lobulations and low signal bands/septations, was observed in 63% (24/38) of lesions. Lesions commonly demonstrated prominent intra-lesional (30/39, 75%) and peripheral juxta-lesional flow voids. Local invasion of surrounding structures was uncommon (3/39, 8%). Mitotically active lesions (p = 0.02) and lesions with tumor necrosis (p < 0.01) were larger in size. Tumor necrosis was associated with T1 heterogeneity (p = 0.04). Distant metastasis occurred in 10% (4/39) of patients, all in mitotically active lesions pre-operatively considered at least at intermediate risk of metastasis.

CONCLUSION

MSK-SFTs commonly present as well-defined, hypervascular masses deep to fascia along major neurovascular bundles, with heterogeneous slightly hyperintense T1 signal, intermediate-to-high T2/STIR signal, and prominent macroscopic flow voids.

Primary intraperitoneal solitary fibrous tumor in mesentery: How does it present?

Intra-abdominal solitary fibrous tumor (SFT), also known as hemangiopericytoma, is rare, especially for those with a mesenteric location, and only a few cases have been reported. Distinguishing a hemangiopericytoma from other intra-abdominal benign or malignant tumors can be difficult, as they have similar presentations on both computed tomography and magnetic resonance imaging. In the present study, the records for a 31-year-old Vietnamese woman who underwent abdominal surgery for greater omental tumor resection and received histopathological results revealing SFT are retrospectively reviewed. The case is discussed and similar reported cases are reviewed. Due to the aggressive behavior and high rate of postoperative recurrence associated with SFT, a thorough understanding of the radiologic and histopathological features of the disease is necessary to achieve an appropriate diagnosis and treatment.

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.

MR imaging of Nasal and Paranasal Sinus Malignant Neoplasms

MRI is useful for evaluating sinonasal malignancies. In particular, MRI can provide important information pertinent to treatment planning, such as delineating the presence of intracranial and orbital extension. This article reviews the MRI protocols, staging, imaging features, and differential diagnosis related to malignant nasal and paranasal sinus neoplasms.

[Solitary fibrous tumor of the prostate: case report]

La tumeur fibreuse solitaire est une tumeur mésenchymateuse souvent bénigne et rare décrite pour la première fois dans la plèvre, la localisation prostatique est exceptionnelle. Nous rapportons le cas d´un patient de 77 ans qui a consulté pour symptômes du bas appareil urinaire à type de dysurie et pollakiurie. Le scanner et l´imagerie par résonance magnétique (IRM) ont montré l´origine prostatique de la lésion et précisé les rapports de cette masse avec les structures adjacentes saines, élément important pour la résécabilité de la tumeur. La biopsie transrectale avec une étude immunohistochimie ont confirmés le diagnostic, les cellules tumorales exprimaient le CD34, Bcl2 et CD 99. Le traitement était chirurgical par prostatectomie radicale.

A case of a large solitary fibrous tumor in the thigh, displaying NAB2ex4-STAT6ex2 gene fusion

A solitary fibrous tumor (SFT) is documented in several body sites. However, there are few reports on the radiological and corresponding histopathological, including immunohistochemical, features of SFT in the lower extremities. A 58-year-old male presented with a lump in his right thigh of 6 months duration. Plain radiograph revealed a soft tissue lesion in his right thigh, involving the adjacent mid-diaphysis and showing focal cortical thickening and calcification. Magnetic resonance imaging scans displayed two well-defined, T1-isointense and T2 heterogeneously hyperintense lesions, measuring together 15 cm in the intermuscular plane and the juxtacortical location along the mid-diaphyseal region of the right femur. Radiologically, the differential diagnoses considered were undifferentiated pleomorphic sarcoma and synovial sarcoma. Microscopic examination of the core biopsy and the resected tumor revealed a tumor composed of cells with oval to spindle-shaped nuclei in a variably collagenized stroma, including hyalinized blood vessels and focal dystrophic calcification. Mitotic figures were 4/10 high power fields. Immunohistochemically, the tumor cells were positive for CD34, BCL2, and STAT6. Diagnosis of malignant SFT was offered. The tumor displayed NAB2ex4-STAT6ex2 gene fusion on molecular testing. This constitutes a relatively uncommon case report of a large SFT in the thigh, including its radiological and pathological features, confirmed by STAT6 immunostaining. An SFT should be considered in cases of slow-growing, well-defined soft tissue tumors, which are isointense on T1 and heterogeneously hyperintense on T2-weighted sequences, and display calcification and cortical thickening of the adjacent bones. Various differential diagnoses and their treatment-related implications in such cases are discussed herewith.

Solitary fibrous tumor of the urinary bladder: An unusual case report with literature review

Solitary fibrous tumor is neoplasm of mesenchymal origin commonly involving visceral pleura however we are presenting an unusual case with involvement of urinary bladder. It is generally indolent in nature therefore proper diagnosis is required for complete characterization to avoid unnecessary extensive surgical resection. Our patient was a 64-year-old female who presented with lower abdominal fullness with change in her bowel movement pattern. On imaging partially necrotic mass with heterogenous enhancement was found which was later biopsied and resected with clean surgical margin. Solitary fibrous tumor is overall a benign tumor with satisfactory outcome. Physicians should keep it in a differential of pelvic masses and with the risk recurrence, 6 monthly follow up imaging are usually required after resection.

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.

Metastatic intracranial solitary fibrous tumors/hemangiopericytomas: description of two cases with radically different behaviors and review of the literature

Solitary fibrous tumor/hemangiopericytoma with primary tumor location in the central nervous system accounts for less than 1% of all central nervous system tumors. Despite the relatively indolent clinical course, extracranial metastases are reported in 28% of cases. In recent years, NAB2-STAT6 gene fusion has been recognized as the pathognomonic molecular feature of solitary fibrous tumor/hemangiopericytoma and STAT6 immunohistochemistry has been shown to be a sensitive and specific surrogate for the identification of the gene fusion in these patients. Here we report two cases of patients who experienced occurrence of diffuse extracranial metastases several years after successful surgery for an intracranial solitary fibrous tumor/hemangiopericytoma. In the first patient, the metastases had maintained similar histological features to the primary tumor; in contrast, in the second case, a dedifferentiation occurred with loss of expression of CD34 and Bcl-2. These different histological features were associated with radically different behaviors. Whereas the first case experienced an indolent course of the disease, the second patient had a rapid disease progression and deterioration of clinical conditions. The molecular imaging findings in these two cases and the role of functional imaging for tumor detection, disease staging and monitoring in this rare cancer are also discussed. Recurrences and metastases maintained high expression of somatostatin receptors confirmed by somatostatin receptor imaging in the first case. In contrast, in the second patient, the abrupt transition into a highly aggressive form was associated with the absence of somatostatin receptors at 111In Pentetreotide scan and intense hypermetabolism at 18F-FDG PET.