Updates in the approach to intrathoracic sarcomas

Rare presentation of solitary fibrous tumour in the floor of the mouth

A male in his 20s, a tobacco chewer, presented to the outpatient department with a history of painless, slowly progressive swelling in the floor of the mouth. After a thorough history and clinical examination, MRI was done and the tumour was completely excised. Histopathological examination revealed the mass to be a solitary fibrous tumour, confirmed with immunohistochemical markers. On subsequent follow-ups, the patient was found to be asymptomatic with no clinical signs of recurrence.

Exploring Solitary Fibrous Tumors at a Tertiary Cancer Center: Clinicopathological and Immunomorphologic Profile

Background Solitary fibrous tumor (SFT) is a distinct fibroblastic tumor that can occur at any anatomical site and can manifest a variety of histopathological features. NAB2-STAT6 gene fusion has recently emerged as a sensitive and specific molecular marker and its surrogate on immunohistochemistry, STAT6 has also displayed considerable efficacy. Nevertheless, its histologic diversity can result in diagnostic challenges, especially when classic features are not apparent. Methods A retrospective study was conducted at a tertiary cancer centre in North India over 3 years to document the clinicopathologic and immunomorphologic profile of SFTs. Immunohistochemical analysis of BCOR and p53 were gauged additionally and patients were stratified according to Modified Demicco and Salas criteria for risk of metastasis. Results Sixteen patients of SFT were identified, affecting middle-aged men and women equally. Though lung/pleura are known to be involved commonly, SFT affects other sites such as the kidney, brain, buccal mucosa, liver, and penis as well. The majority endured localized disease while a lesser number suffered locoregional/distant spread. Two patients revealed features of a malignant profile. Risk stratification according to the Modified Demicco and Salas criteria evinced comparable results. No discernible relationship however was highlighted between the immunohistochemical expression of BCOR, p53, and any significant SFT parameter. Conclusion Although SFTs are very rare substantially benign mesenchymal neoplasms, pathologists must be conversant with their histological diversity and be vigilant of their malignant attributes. The worth of STAT6 immunohistochemistry for precise diagnosis and long-term studies for delineating clinical behavior cannot be overemphasized.

Clinicopathological Features of Intrathoracic Liposarcoma-A Systematic Review with an Illustrative Case

BACKGROUND

Liposarcoma (LPS) is one of the most common soft-tissue sarcomas. However, intrathoracic LPS is rare, as only 1% of all LPS cases are found in the thorax.

METHODS

A systematic literature review through PubMed and Embase databases was performed. Only eligible case reports and case series reporting intrathoracic LPS in adult patients were included. Kaplan-Meier curves were calculated to evaluate the survival rate of included patients based on the histological subtype of LPS.

RESULTS

123 studies reporting 197 patients were included. We added a case of a 69-year-old female patient with recurrent giant intrathoracic LPS. The primary tumor measured 15.1cm × 22.9 cm × 21.9 cm and weighed 3100 g. Six months later, the patient was admitted to the hospital with another intrathoracic tumor measuring 9.5 cm × 9 cm× 1.4 cm. The immunohistochemical studies showed expression of murine double minute 2 (MDM2) antigen in both primary and recurrent tumor cells.

CONCLUSIONS

Dyspnea, chest pain, and cough were the most common symptoms reported in included studies. Overall, the 5-year survival rate was 62%. The highest survival was observed in well-differentiated LPS patients (80%) and the lowest in myxoid LPS (31%).

Magnetic resonance imaging features of a solitary fibrous tumor of the vulva: a case report

Solitary fibrous tumors (SFTs) are commonly seen in the pleura. SFT involvement of the vulva is rare, and clinical diagnosis is mainly based on histopathological and immunohistochemical analyses. We herein describe the imaging features of a 69-year-old woman with an SFT of the vulva. The SFT was hypointense on T1-weighted images, similar to muscle; however, it showed inhomogeneous hyperintensity predominantly on fat-suppressed T2-weighted images. An area of low signal intensity was evident on T2-weighted images, and the tumor showed progressive enhancement in delayed phases. The tumor also displayed heterogeneous and prolonged, persistent enhancement, and serpentine vessels were present in the peritumoral area as signal voids. Pathological examination confirmed that the lesion was an atypical SFT originating from the vulva, and it was composed of spindle cells and perivascular and stromal hyalinization. This case reveals the characteristic imaging findings of vulvar SFT and their association with the relevant pathological findings, thus contributing to the primary diagnosis and preoperative evaluation of this potentially aggressive tumor.

Primary epithelioid angiosarcoma of the mediastinum, cytomorphologic features of a rare entity-A case report and literature review

Epithelioid angiosarcoma (EA) is a highly aggressive vascular neoplasm. Primary mediastinal EA is extremely rare with only few cases reported in the English literature. We herein present a case of a 78-year-old patient, who was found to have a right superior mediastinal mass associated with mediastinal and hilar lymphadenopathy. Endobronchial ultrasound guided fine needle aspiration cytology of a station 4R lymph node revealed a cellular, discohesive malignant neoplasm displaying primarily epithelioid morphology with occasional spindled, plasmacytoid, and tumor giant cells. The tumor cells had ample eosinophilic cytoplasm with pleomorphic nuclei and prominent nucleoli. Vasoformative features were noted, exemplified by widespread cytoplasmic vacuoles containing neutrophils and rare red blood cells (hemophagocytosis) and vascular channels identified solely in the cell block. By immunohistochemistry, the tumor cells stained strongly positive for vimentin, positive for ERG, CD-31, FLI-1, and focally positive for pan-cytokeratin. The cytomorphological features and immunostaining patterns were diagnostic of EA. No history of malignancy was reported, and no other lesions were identified on imaging. The diagnosis of primary mediastinal EA on cytology and small biopsy specimens may be challenging due to the rarity of this tumor, limited diagnostic material, and overlapping morphologic features with other entities in the differential diagnosis. A high index of suspicion, especially in cases with vasoformative features, and utilization of ancillary studies can help establish the diagnosis.

Mesenchymal Tumors of the Mediastinum: An Update on Diagnostic Approach

Mesenchymal tumors of the mediastinum are a heterogenous group of rare tumors with divergent lineages. Mediastinal mesenchymal tumors are diagnostically challenging due to their diversity and morphologic overlap with nonmesenchymal lesions arising in the mediastinum. Accurate histologic diagnosis is critical for appropriate patient management and prognostication. Many mediastinal mesenchymal tumors affect distinct age groups or occur at specific mediastinal compartments. Neurogenic tumors, liposarcoma, solitary fibrous tumor, and synovial sarcoma are common mesenchymal tumors in the mediastinum. Herein, we provide an update on the diagnostic approach to mediastinal mesenchymal tumors and a review of the histologic features and differential diagnosis of common benign and malignant mesenchymal tumors of the mediastinum.

Liposarcoma of the pelvic fossa masquerading as hematoma: a rare case report and its surgical management

Liposarcomas constitute rare malignant tumors of the soft tissue, with wide anatomical distribution. The prompt diagnosis of a liposarcoma is extremely challenging since these tumors tend to remain asymptomatic, until they grow enough to displace adjacent anatomical structures. In the presented case, a 55-year-old Caucasian male proceeded to our institution complaining about irreducible swelling of the right iliac fossa and constant discomfort, over the course of a year. His medical history revealed injury of the right groin and pelvis a year ago. The diagnosis was ilioinguinal liposarcoma masquerading as hematoma, due to the previous injury. The patient underwent primary complete tumor resection, and the operation was uneventful. The essential diagnostic and surgical steps for the management of a liposarcoma, mimicking a hematoma are meticulously described.

The many faces of solitary fibrous tumor; diversity of histological features, differential diagnosis and role of molecular studies and surrogate markers in avoiding misdiagnosis and predicting the behavior

Background

Solitary Fibrous Tumor (SFT) is a distinct soft tissue neoplasm associated with NAB2-STAT6 gene fusion. It can involve a number of anatomic sites and exhibits a wide spectrum of histological features.

Main body

Apart from diversity in morphological features seen even in conventional SFT, two histologic variants (fat-forming and giant cell-rich) are also recognized. In addition, a malignant form and dedifferentiation are well recognized. Owing to diverse histological features and involvement of diverse anatomic locations, SFT can mimic other soft tissue neoplasms of different lineages including schwannoma, spindle cell lipoma, dermatofibrosarcoma protuberans, liposarcoma, gastrointestinal stromal tumor (GIST), malignant peripheral nerve sheath tumor (MPNST), and synovial sarcoma. SFT is classified as an intermediate (rarely metastasizing) tumor according to World Health Organization Classification of Tumors of Soft tissue and Bone, 5th edition. The management and prognosis of SFT differs from its malignant mimics and correct diagnosis is therefore important. Although SFT expresses a distinct immunohistochemical (IHC) profile, the classic histomorphological and IHC profile is not seen in all cases and diagnosis can be challenging. NAB2-STAT6 gene fusion has recently emerged as a sensitive and specific molecular marker and its IHC surrogate marker signal transducer and activator of transcription 6 (STAT6) has also shown significant sensitivity and specificity. However, few recent studies have reported STAT6 expression in other soft tissue neoplasms.

Conclusion

This review will focus on describing the diversity of histological features of SFT, differential diagnoses and discussing the features helpful in distinguishing SFT from its histological mimics.

Primary Intrathoracic Sarcomas: A Review of Cross-sectional Imaging and Pathology

The most common sarcomas in the thorax are metastasis from an extrathoracic primary malignancy. Primary intrathoracic sarcomas are rare albeit aggressive malignancies that are diagnosed on histopathology. Although a few imaging characteristics have been described that are common to sarcomas, it is still a diagnosis of exclusion as other tumors are much more common. Like elsewhere, primary thoracic sarcomas are also classified according to their histologic features. They are a rare group of tumors that can arise from the mediastinal structures, lung, pleura, or chest wall. On imaging, differentiating these from more common malignancies like lung cancer is difficult and often requires multimodality workup and tissue sampling. A few sarcomas are very specific to their locations, such as angiosarcoma in the right atrium, leiomyosarcoma in the pulmonary artery, where imaging has high accuracy for the diagnosis. Despite being nonspecific in a majority of cases, imaging plays a pivotal role in determining the organ of origin, tumor extent, invasion of adjacent structures, and thus help to assess the surgical resectability. Although sarcomas arising from chest wall are the most common primary sarcomas in the chest, they are excluded from this review to focus only on primary intrathoracic sarcomas. The article provides a comprehensive imaging and pathology review of the rare primary intrathoracic sarcomas, including but not limited to angiosarcoma, Kaposi sarcoma, fibrosarcoma, malignant transformation of fibrous tumor of pleura, sarcomatoid mesothelioma, leiomyosarcoma, and malignant small round blue cell tumors.Key points:Primary intrathoracic sarcomas are rare but clinically important.Imaging helps to determine local extent, invasion, metastases and appropriate site/mode of biopsy.Role of pathology is paramount in diagnosis and guiding treatment based on immunogenetic/molecular typing.

Retroperitoneal Sarcomas: An Update on the Diagnostic Pathology Approach

Retroperitoneal sarcomas are a heterogenous group of rare tumors arising in the retroperitoneum. Retroperitoneal sarcomas comprise approximately 10% of all soft tissue sarcomas. Though any soft tissue sarcoma histologic types may arise in the retroperitoneal space, liposarcoma (especially well-differentiated and dedifferentiated types) and leiomyosarcoma do so most commonly. Retroperitoneal sarcomas are diagnostically challenging, owing to their diversity and morphological overlap with other tumors arising in the retroperitoneum. An accurate diagnosis is necessary for correct management and prognostication. Herein, we provide an update on the diagnostic approach to retroperitoneal sarcomas and review their key histologic findings and differential diagnoses.

Primary pleural liposarcoma combined spindle cell lipoma of the lung

Liposarcoma is a malignant adipose tissue tumor which mainly originates from the extremities and retroperitoneum. Primary pleural liposarcoma is very rare. Spindle cell lipoma is a rare benign adipose tissue tumor. A 66‐year‐old male was referred to our hospital for the evaluation of a mass‐like opacity visible on chest X‐ray. Computed tomography (CT) scan revealed a well‐defined soft tissue mass with internal low attenuations and adjacent multiple nodules in the upper lobe of the left lung, and surgical excision was subsequently performed. Histopathological findings revealed adipose tissue with lipoblasts and spindle cells and immunohistochemical staining (IHC) revealed the tumor cells were strongly positive for CDK4 and MDM2. Histopathological examination of the small lung nodules showed spindle cell proliferation and adipose tissue without positivity for MDM2. Here, we report a rare case of primary pleural liposarcoma combined adjacent spindle cell lipoma of the lung.

Radiation Therapy in Resectable Intrathoracic Sarcomas. A Rare Cancer Network Study

PURPOSE

Intrathoracic sarcomas (ITS) are considered rare tumors and have a dismal prognosis. We investigated outcomes and risk factors for local control (LC), disease-free survival (DFS), and overall survival (OS) in patients with resected nonmetastatic ITS treated with or without adjuvant radiation therapy (RT) and/or chemotherapy.

METHODS AND MATERIALS

Patients from the Rare Cancer Network database were studied. A Kaplan-Meier estimate was used to assess survival curves, and Cox proportional hazards regression was used to assess risk factors for LC, DFS, and OS.

RESULTS

Between 2000 and 2017, 121 patients met inclusion criteria. The primary site was lung in 30%, mediastinum in 34%, and pleura in 36%. Thirty-nine percent and 32% received RT and chemotherapy. Median follow-up was 34 months (range, 2-141). LC, DFS, and OS at 10 years were 52%, 18.7%, and 7.2%, respectively. In multivariate analysis, RT (P = .003) and R1 margin status (P = .041) retained a significant association with LC. Only R1 resection (P = .002) remained associated with an increased risk of death in multivariate analysis. Overall, 7 patients (6%) developed grade 3 treatment-related chronic toxicity events.

CONCLUSIONS

This joint analysis revealed that OS remains modest in this group of patients, mainly given by the high risk of local and distant failure. Our results suggest that resected ITS can benefit from adjuvant RT.

Rapidly growing pleural liposarcoma masquerading as extrapleural hematoma

Intrathoracic liposarcoma can occur in the lung, mediastinum, pleura, and chest wall, and tends to remain clinically silent until becoming large enough to displace adjacent structures. Treatment usually includes sufficient surgical resection followed when necessary by adjuvant chemoradiotherapy. We report a case of an uncommon presentation of a rapidly growing pleural liposarcoma, the diagnosis of which may have been obscured by coexisting thoracic trauma with suspected extrapleural hematoma.

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

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

The Current Status of Solitary Fibrous Tumor: Diagnostic Features, Variants, and Genetics

Solitary fibrous tumor (SFT) is a fibroblastic mesenchymal tumor originally described in the pleura but now shown at almost every anatomic site. Histopathologically, SFT is characteristically a circumscribed neoplasm composed of variably cellular and patternless distributions of bland spindle and ovoid cells within prominent collagenous stroma and shows diffuse expression of CD34, but it has a broad spectrum of both morphology and of biologic behavior. Many different names (particularly hemangiopericytoma) were previously used in the course of our understanding of this neoplasm but are now subsumed under the term "SFT," and the putative cell of origin was debated. However, it is now recognized that SFT is a translocation-associated neoplasm, consistently associated with NAB2-STAT6 gene fusions arising from recurrent intrachromosomal rearrangements on chromosome 12q, and this translocation is a likely major contributor to its pathogenesis. While most SFT with classical morphologic features behave in an indolent manner and those with overtly malignant histologic features tend to be aggressive neoplasms that behave as high-grade sarcomas, the behavior of SFT is unpredictable, and it is important to be aware of the propensity for aggressive behavior in a minority of histologically classical SFT and to ensure adequate clinical follow-up. Surgical excision remains the treatment gold standard; while radiotherapy and conventional chemotherapeutic agents have only shown limited efficacy, further understanding of the molecular events underlying tumorigenesis may allow the development of novel targeted treatments. We review SFT, discussing the morphologic spectrum and variants, including malignant and dedifferentiated subtypes, clinicopathological aspects, recent molecular genetic findings, and the differential diagnosis.