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

Review of Imaging Peritoneal Disease and Treatment

Peritoneal disease can be classified as either benign or malignant in nature. Malignant peritoneal disease can be further considered as either primary or secondary in origin. Primary peritoneal malignancy includes peritoneal mesothelioma, serous carcinoma, and desmoplastic small round cell tumour. Peritoneal carcinomatosis is the most commonly encountered secondary malignant peritoneal disease, typically of ovarian, gastric, colorectal, pancreatic, small bowel neuroendocrine, or breast origin. Others include peritoneal lymphomatosis and sarcomatosis. Benign peritoneal pathology may mimic malignant disease. Differentiating benign from malignant peritoneal pathology can be challenging, but is critical to guide appropriate care and avoid unnecessary intervention. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) offers potentially curative treatment for patients with peritoneal carcinomatosis, pseudomyxoma peritonei, and peritoneal mesothelioma. For such patients, the radiologist provides crucial pre-operative information highlighting sites of disease involvement, particularly for sites which are challenging to assess at laparotomy or laparoscopy, including the hepatic dome, subdiaphragmatic space and mesenteric root. The radiologist is also essential to identify potential contraindications to surgery, as well as interpreting normal post-operative appearances, complications and assessing for disease recurrence.

Case report: A rare case of malignant solitary fibrous tumor in an adult with an epithelioid pattern in the occipital region

We illustrated a rare case of malignant solitary fibrous tumor (MSFT) with epithelioid morphology in the occipital region of a 59-year-old female, in which a rare NAB2ex7-STAT6 exon15/16 double fusion subtype was detected by the Next-generation sequencing (NGS) and STAT6 immunohistochemistry (IHC) was diffusely and strongly positively expressed, without recurrence after 20 months of postoperative follow-up. The morphological and molecular genetic aspects and the differential diagnosis are described, and the relevant literature was assessed in order to broaden our understanding and diagnostic capability of this malignancy.

A 73-Year-Old Female Diagnosed With Dermatofibrosarcoma Protuberans in the Primary Care Setting: A Case Report and Literature Review of Misdiagnosed Cases

Dermatofibrosarcoma protuberans (DFSP) is a rare, slow-growing, malignant tumor in the dermis and subcutaneous fat diagnosed by pathological and immunohistochemical examinations. This case report provides the dermatological findings of a 73-year-old woman with DFSP who presented to a primary care clinic with a longstanding nodular lesion on her left upper thigh. Dermatological examination showed a solitary, skin-colored violaceous/hyperpigmented nodule on the superior anteromedial portion of the left thigh. A punch biopsy revealed spindle cell proliferation, and diffuse CD34 positivity, confirming the diagnosis of DFSP. A dermatology referral was placed for further management and complete surgical excision. Patient underwent wide local excision (WLE) and has no recurrence to date. Unfortunately, DFSP is commonly misdiagnosed before skin biopsy which delays treatment. This case is significant because DFSP is not often diagnosed accurately outside the dermatology specialty and serves as a reminder to practitioners to use biopsies during the diagnostic process of skin findings to prevent the delay in management.

Solitary Fibrous Tumours of the Orbit - Clinical Pathology, Therapy and Prognosis

BACKGROUND

Solitary fibrous tumours are rare. The aim of this study is to describe the clinical features, therapy and outcome of affected patients and to identify factors associated with recurrence.

METHODS

Retrospective study of a cohort of 20 patients who underwent surgery for orbital solitary fibrous tumour at the University Department of Oral and Maxillofacial Surgery between 2002 and 2023. Demographic, clinical, and therapeutic data as well as tumour follow-up results were collected. Tumour volume and molecular genetic mutations were retrospectively determined.

RESULTS

The median patient age was 49.5 years at initial surgery. The left orbit was affected in 65% of cases. The most common clinical symptom was proptosis (80%). This was reported with a mean lateral difference of 3.9 mm (range: 1 - 10 mm). The tumours were localised predominantly in the intra- and extraconal space, craniolateral quadrant and middle third. The median tumour volume was 7.66 cm³ (range 2.15 - 12.57 cm³). In all patients, the diagnosis was made by pathological examination. All tumours investigated showed a NAB2-STAT6 mutation. The most frequently detected mutation was the fusion NAB2 exon 4 - STAT6 exon 2. All patients were initially managed with frontolateral orbitotomy. Incomplete resection (R1-status) occurred in 35% (n = 7). The recurrence rate was 25% (n = 5), with a median disease-free interval of 45.5 months (range 23 - 130). 80% (n = 4) of recurrences were initially R1-resected.

CONCLUSION

Orbital solitary fibrous tumours are rare tumours and are clinically manifested by signs of displacement of orbital structures. Diagnosis is made by histology and immunohistochemistry and can be proven with the molecular genetic detection of the NAB2-STAT6 mutation. The therapy of choice is complete surgical resection. R1-resection is more likely in the intraconal location as well as in location in the posterior third of the orbit - due to difficult surgical accessibility. The greatest risk factor for the development of recurrence is incomplete surgical excision. Late recurrences are possible, which is why a long-term connection to a specialised clinic is necessary.

Adrenal Solitary Fibrous Tumor: A Case Report

Solitary fibrous tumor is a mesenchymal neoplasm that first appeared in the literature as a pleural lesion, but over the last decades, it has been reported in many extrathoracic sites. Primary solitary fibrous tumor in the adrenal gland is very uncommon. Its biological behavior is variable but mostly benign. We report here a case of an apparently healthy woman who, in the context of the study of limb paresthesias, was diagnosed with an adrenal incidentaloma. Laboratory tests were performed, and no hormone hyperfunction was detected. Subsequently, a right adrenalectomy was performed, and the pathological study confirmed a solitary fibrous tumor. To the best of our knowledge, this is the 19th case reported in the literature of a primary solitary fibrous tumor originating from the adrenal gland and, notably, the first documented instance in Spain.

Malignant Solitary Fibrous Tumor of the Inguinal Region: A Case Report

A solitary fibrous tumor (SFT) is a rare spindle cell neoplasm in adults, usually found in the pleural and thoracic cavities. We report an interesting case of a malignant solitary fibrous tumor in a 64-year-old male who presented with a history of swelling in his right inguinal region that gradually increased in size during the past three years. Computed tomography (CT) and magnetic resonance imaging (MRI) scans of the abdomen and pelvis showed a rounded solid mass originating from the right inguinal canal suggestive of sarcoma. Elective excision of the mass was done under general anesthesia with histopathology confirming the diagnosis of high-grade spindle cell sarcoma in keeping with a malignant solitary fibrous tumor. Postoperatively, the patient had no complications and was discharged on postoperative day 4. The patient was then treated with radiotherapy. He remained free of recurrence for two years postoperatively.

Bone and soft tissue tumors at the borderlands of malignancy

This review examines findings of musculoskeletal neoplasms whose equivocal imaging and/or histopathologic features make it difficult to determine if they will show aggressive behavior. We include both intermediate tumors as defined by the World Health Organization (WHO), and a single low-grade malignancy, low-grade central osteosarcoma, which mimics a benign lesion on imaging and histology. Intermediate tumors are a broad category and are subdivided into tumors that have risk of local recurrence only, and ones that have a risk of distant limb and pulmonary metastases. Difficult intermediate musculoskeletal lesions include atypical cartilaginous tumor/grade 1 chondrosarcoma, atypical lipomatous tumor/grade 1 liposarcoma, and solitary fibrous tumor. We review diagnostic criteria, differential diagnosis, and recommendations for surveillance.

Paraneoplastic Syndromes from Head to Toe: Pathophysiology, Imaging Features, and Workup

Patients often have symptoms due to the mass effect of a neoplasm on surrounding tissues or the development of distant metastases. However, some patients may present with clinical symptoms that are not attributable to direct tumor invasion. In particular, certain tumors may release substances such as hormones or cytokines or trigger an immune cross-reactivity between malignant and normal body cells, resulting in characteristic clinical features that are broadly referred to as paraneoplastic syndromes (PNSs). Recent advances in medicine have improved the understanding of the pathogenesis of PNSs and enhanced their diagnosis and treatment. It is estimated that 8% of patients with cancer develop a PNS. Diverse organ systems may be involved, most notably the neurologic, musculoskeletal, endocrinologic, dermatologic, gastrointestinal, and cardiovascular systems. Knowledge of various PNSs is necessary, as these syndromes may precede tumor development, complicate the patient's clinical presentation, indicate tumor prognosis, or be mistaken for metastatic spread. Radiologists should be familiar with the clinical presentations of common PNSs and the selection of appropriate imaging examinations. Many of these PNSs have imaging features that can assist with arriving at the correct diagnosis. Therefore, the key radiographic findings associated with these PNSs and the diagnostic pitfalls that can be encountered during imaging are important, as their detection can facilitate early identification of the underlying tumor, reveal early recurrence, and enable monitoring of the patient's response to therapy. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Solitary Fibrous Tumors of the Lung: A Clinicopathological Analysis of 52 Cases

OBJECTIVE

To explore the clinicopathological features of solitary fibrous tumors (SFTs) of the lung.

METHODS

We collected the clinical data of 52 patients with SFTs of the lung confirmed by pathology, and summarized the clinical, radiological, and morphological features, the immunophenotypes, and the prognosis of SFTs.

RESULTS

Fifty-two cases of SFTs of the lung were enrolled in this study, including 51 cases of borderline and 1 case of malignancy, 22 males and 30 females. The average onset age was 52.7 years. The lower lobe of the left lung was the preferred site of SFTs, accounting for 30.77% (16/52). Chest CT showed regular and well-demarcated soft tissue density mass, and the tumor size of most cases (46/52, 88.46%) was 1-10 cm. Morphological features: The distribution of tumor cells showed sparse and dense areas. Tumor cells were spindle-shaped, in whorls or hemangiopericytoma-like conformation. Atypia, mitotic figures, and necrosis were found. Immunohistochemistry showed positive expression of CD34, STAT6, Vimentin, BCL2, and CD99. Ki-67 was ≤ 5% in borderline SFTs and >20% in a malignant SFT.

CONCLUSIONS

Solitary fibrous tumors of the lung occur more frequently in middle-aged and elderly people, and there is no significant difference in gender. The lower lobe of the left lung is the preferred site of SFTs. The size of most SFTs is 1-10 cm. Chest CT shows morphologically regular and well-demarcated soft tissue density mass. Pathologically, SFTs of the lung are mostly borderline and occasionally malignant. Immunohistochemistry shows the positive expression of CD34, STAT6, Vimentin, BCL2, and CD99.

Metastasis of a Solitary Fibrous Tumor in the Mandible: A Case Report

BACKGROUND/AIM

The solitary fibrous tumor (SFT) is a mesenchymal neoplasm and belongs to the group of soft tissue sarcomas. The SFT is characterized by indolent, slowly progressive growth and manifests itself clinically by compression of neighboring structures. The treatment of choice is surgical removal of the tumor. In advanced stages, there is also the possibility of chemotherapy, systemic therapy, or immunotherapy, as well as radiotherapy. Depending on their location and severity, SFTs show different recurrence rates and survival functions.

CASE REPORT

The present case report shows an extremely rare localization of a low-risk SFT in the floor of the mouth. Despite complete surgical removal of the SFT, the patient showed a metastasis of the SFT in the mandible two years postoperatively. Therefore, this case report shows that even a low-risk SFT in the localized stage can metastasize despite of total surgical removal. Consequently, SFTs of the head and neck region require close clinical and imaging follow-up.

CONCLUSION

Although the localization of the SFT in the oral cavity is a rarity, this entity should be included in the differential diagnosis in the case of long-term space-occupying processes in the head and neck region. This report is the first regarding metastasis of a SFT to the mandible.

Extrapleural Malignant Solitary Fibrous Tumor Presenting as Invasive Bilateral Paravertebral Tumors: A Case Report

Solitary fibrous tumors (SFTs) commonly arise from the pleura and are mostly benign. However, they may develop anywhere in the body, and 10%-30% are malignant. Classically, SFTs appear as solitary enhancing masses, and bilateral presentation is extremely rare. In this case, an 88-year-old male presented with back pain and a history of chronic tuberculous empyema. Imaging studies revealed bilateral paravertebral masses with aggressive radiologic features, which were speculatively presumed as thoracic malignancies in association with chronic empyema. Herein, we report a unique case of bilateral paravertebral malignant SFTs that were accurately diagnosed with a CT-guided coaxial needle biopsy.