Mediastinal germ cell tumors with an angiosarcomatous component: a report of 12 cases

The genetics of vascular tumours: an update

Recent molecular advances have shed significant light on the classification of vascular tumours. Except for haemangiomas, vascular lesions remain difficult to diagnose, owing to their rarity and overlapping clinical, radiographic and histological features across malignancies. In particular, challenges still remain in the differential diagnosis of epithelioid vascular tumours, including epithelioid haemangioma and epithelioid haemangioendothelioma at the benign/low-grade end of the spectrum, and epithelioid angiosarcoma at the high-grade end. Historically, the classification of vascular tumours has been heavily dependent on the clinical setting and histological features, as traditional immunohistochemical markers across the group have often been non-discriminatory. The increased application of next-generation sequencing in clinical practice, in particular targeted RNA sequencing (such as Archer, Illumina), has led to numerous novel discoveries, mainly recurrent gene fusions (e.g. those involving FOS, FOSB, YAP1, and WWTR1), which have resulted in refined tumour classification and improved diagnostic reproducibility for vascular tumours. However, other molecular alterations besides fusions have been discovered in vascular tumours, including somatic mutations (e.g. involving GNA family and IDH genes) in a variety of haemangiomas, as well as copy number alterations in high-grade angiosarcomas (e.g. MYC amplifications). Moreover, the translation of these novel molecular abnormalities into diagnostic ancillary markers, either fluorescence in-situ hybridisation probes or surrogate immunohistochemical markers (FOSB, CAMTA1, YAP1, and MYC), has been remarkable. This review will focus on the latest molecular discoveries covering both benign and malignant vascular tumours, and will provide practical diagnostic algorithms, highlighting frequently encountered pitfalls and challenges in the diagnosis of vascular lesions.

Chromosome 8 Polysomy Accounting for MYC Over-Expression in Angiosarcoma Arising as Somatic-Type Malignancy in Metastatic Teratoma. Case Report

MYC over-expression by immunohistochemistry (IHC) is utilised in routine pathology practice as a surrogate marker for MYC amplification, which plays a key oncogenic role in post-irradiation and chronic lymphedema-associated angiosarcoma. We present the case of a 32-year old male, who presented with high-grade angiosarcoma arising in a background of metastatic testicular teratoma. IHC for MYC showed strong nuclear expression in the angiosarcoma cells prompting the consideration of post-irradiation-induced angiosarcoma but our patient did not undergo radiotherapy. Fluorescence in-situ hybridization (FISH) excluded MYC amplification and instead showed Chromosome 8 polysomy, which accounted for the strong MYC IHC expression present, not previously described in the context of germ cell tumours. The occurrence of MYC over-expression due to polysomy illustrates a novel clinical scenario (angiosarcoma arising as somatic malignancy) where strong MYC IHC expression can be found in the absence of underlying amplification or prior radiotherapy exposure.

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.

Vasculogenic Mesenchymal Tumor: A Clinicopathologic and Molecular Study of 55 Cases of a Distinctive Neoplasm Originating From Mediastinal Yolk Sac Tumor and an Occasional Precursor to Angiosarcoma

We report 55 postchemotherapy resections of primary nonseminomatous mediastinal germ cell tumors with prominent vasculogenic features showing the formation of rudimentary to well-developed neoplastic vessels within primitive mesenchyme. These cases represented 25% of a cohort of 221 such specimens. The patients were 19 to 49 years old (mean, 28 y) and 98% had serological evidence of yolk sac tumor. The vasculogenic lesions, felt to represent a neoplastic reiteration of embryonic vasculogenesis in the splanchnic mesoderm of the yolk sac, were further subdivided into teratoma with vasculogenic stroma (n=9), vasculogenic mesenchymal tumor (VMT) (n=42, further classified into low grade [n=24] and high grade [n=18]), and angiosarcoma (n=4). The distinction of teratoma with vasculogenic stroma from VMT was based solely on the greater extent of VMT (exceeding 1 low power [×4 objective] microscopic field), with both categories showing a spectrum of vessels lined by atypical endothelium in a nonendothelial neoplastic stroma that often also generated vascular walls comprised of atypical smooth muscle. The angiosarcomas showed stratification of highly atypical endothelial cells or anastomosing vessels lined by nonstratified but cytologically similar endothelium. Immunohistochemical studies supported the generation of neoplastic vessels from the tumor stroma, most commonly by the development of stromal clefts showing reactivity for podoplanin, CD34, and occasionally ERG, followed by the gradual development from the clefts of thin-walled vessels that later became encircled by stromal cells showing smooth muscle differentiation by immunohistochemistry. Occasionally, round collections of stromal erythrocytes became surrounded by stromal cells to generate blood vessels. Fluorescence in situ hybridization showed chromosome 12p copy number increase in both the endothelial component and stromal component in 8/9 VMT cases and in 1/1 angiosarcoma. On follow-up, no patient with teratoma with vasculogenic stroma had evidence of a subsequent vascular tumor or sarcoma, whereas 8 of the 35 (23%) patients with VMTs (2 low grade and 6 high grade) and meaningful follow-up developed sarcoma (1 angiosarcoma, 2 rhabdomyosarcomas, and 5 not further characterized). The difference between low-grade and high-grade tumors was of borderline significance (P=0.058). Two of the 4 patients with angiosarcoma died of metastatic angiosarcoma, with the other 2 disease-free at 6.8 and 7 years. Compared with the 165 patients with follow-up and no vasculogenic lesions, there was a highly significant (P=4.3×10-5) association of any vasculogenic lesion with sarcomatoid tumors during the clinical course of VMT patients. In addition, 5/46 patients with follow-up and vasculogenic lesions (11%) died of either leukemia or myelodysplastic syndrome compared with 2 of 166 (1%) lacking them (P=0.0012). Three of the 5 patients had identifiable immature hematopoietic cells within their vasculogenic lesions, but 4 other VMT patients with these did not develop leukemia or myelodysplasia. We conclude: (1) vasculogenic lesions are frequent in postchemotherapy resections of primary mediastinal germ cell tumors with yolk sac tumor components; (2) they mostly consist of neoplastic vessels in a stroma that also generates neoplastic vascular walls of smooth muscle; (3) VMTs are associated with an increased incidence of sarcomas, even though most vasculogenic lesions in this context do not meet criteria for angiosarcoma; (4) the presence of vasculogenic lesions in postchemotherapy resections of primary mediastinal germ cell tumors place patients at increased risk for leukemia or myelodysplasia.

Mediastinal Germ Cell Tumor and Acute Megakaryoblastic Leukemia With Co-occurring KRAS Mutation and Complex Cytogenetics

Young males have a unique but rare predilection to develop mediastinal nonseminomatous germ cell tumors (NSGCTs) and concomitant acute megakaryoblastic leukemia (AMKL). Common cytogenetic and molecular abnormalities such as isochromosome 12p and somatic Tumor Protein P53(TP53) and Phosphatase And Tensin Homolog (PTEN) mutations have been reported in the presumed mutual neoplastic clones of origin. We report the case of a 17-year-old male who presented with a mediastinal NSGCT with high-grade sarcomatous transformation and a diagnosis of AMKL approximately 4 months later. Next-generation sequencing revealed identical KRAS Proto-Oncogene, GTPase (KRAS) p.Ala146Thr, TP53 p.Leu257Pro, and PTEN p.Leu181Pro missense mutations at similar variant allele frequencies in both the NSGCT and AMKL samples. Cytogenetic and microarray analyses detected shared copy gains in all chromosomes except chromosomes 9, 13, and Y. Multiple additional clonal chromosomal alterations were detected in the AMKL sample when compared with the NSGCT. This case emphasizes the shared clonal origins of these malignancies and identifies KRAS and other copy number alterations as potential molecular drivers in a subset of these combined diseases.

Vascular tumors of the mediastinum

Vascular tumors represent only a sliver of all tumors affecting the mediastinum, but they pose diagnostic challenges due to significant overlap among entities, ever-evolving classification schemes, and the exquisite rarity of some of the entities not only in the mediastinum but in pathology practice as a whole. Most of the vascular tumors are better known to the practice of soft tissue pathology, from which some of the knowledge of clinical behavior can be extrapolated. For example, the stratification of epithelioid hemangioendothelioma (EHE) into two biologically separate categories has effectively translated from the somatic soft tissues to the thorax. For other entities, the effective validation of soft tissue parameters is hindered by the small numbers of reported mediastinal cases. Many of the treatment modalities have also transferred over, with the key differences resting on the difficulty in achieving complete surgical resection for mediastinal tumors as opposed to those in the somatic soft tissues. Accordingly, systemic drug therapies have emerged as attractive options for some of the mediastinal vascular tumors, such as kaposiform hemangioendothelioma (KHE) and Kaposi sarcoma (KS). The categories presented herein mirror the classification scheme set forth by the 5th Edition WHO Classification of Soft Tissue and Bone Tumors. This review focuses on the biologically aggressive vascular neoplasms while limiting discussion of the benign entities to relevant comparisons in the differential diagnoses. While distinguishing among the benign entities has academic importance, in practice, the stakes are far higher for diagnosing the biologically aggressive tumors given their marked heterogeneity in clinical outcomes. Practical advice for problem areas in pathology will be reviewed alongside tumor pathobiology, including the latest in molecular diagnostics.

Mediastinal Germ Cell Tumors: Updates in Diagnosis and Management

Primary mediastinal nonseminomatous germ cell tumors represent a rare but important malignancy that occurs in otherwise young and healthy patients. Treatment is challenging and involves cisplatin-based chemotherapy followed by surgery to remove residual disease. Avoiding bleomycin-containing chemotherapy in the treatment of primary mediastinal nonseminomatous germ cell tumors is important. Prechemotherapy and postchemotherapy pathology as well as postoperative serum tumor markers are independent predictors of long-term survival.

Outcomes following surgery for primary mediastinal nonseminomatous germ cell tumors in the cisplatin era

OBJECTIVE

Treatment of primary mediastinal nonseminomatous germ cell tumors involves cisplatin-based chemotherapy followed by surgery to remove residual disease. We undertook a study to determine short and long-term outcomes.

METHODS

A retrospective analysis of patients with primary mediastinal nonseminomatous germ cell tumors who underwent surgery at our institution from 1982 to 2017 was performed.

RESULTS

A total of 255 patients (mean age, 29.2 years) were identified. Acute respiratory distress syndrome occurred postoperatively in 27 patients (10.9%), which was responsible for all 11 (4.3%) postoperative deaths. Of patients who developed acute respiratory distress syndrome, more patients received bleomycin-containing chemotherapy (25 out of 169; 14.8%) than non-bleomycin regimens (2 out of 77; 2.6%) (P = .004). With respect to variables independently predictive of long-term survival, evidence of choriocarcinoma before chemotherapy (n = 12) was determined to be an adverse factor (P = .006). In contrast, biopsy-proven elements of seminoma (n = 34) were predictive of improved survival (P = .04). The worst pathology identified in the residual mediastinal mass after chemotherapy was necrosis in 61 patients (25.0%), teratoma in 84 patients (34.4%), and malignant (persistent germ cell or non-germ cell cancer) in 97 patients (39.8%), which influenced overall survival (P < .001). Additionally, teratoma with stromal atypia (n = 18) demonstrated decreased survival compared with teratoma without atypia (n = 66; P = .031). Patients with malignancy involving >50% of the residual mass (n = 47) had a 2.3-fold increased risk of death compared with ≤50% malignancy (n = 45; P = .008). Finally, elevated postoperative serum tumor markers (n = 40) was significantly predictive of adverse survival (P < .001).

CONCLUSIONS

In the treatment of primary mediastinal nonseminomatous germ cell tumors, avoiding bleomycin-containing chemotherapy is important. Pre- and postchemotherapy pathology and postoperative serum tumor markers are independent predictors of long-term survival.

Development of angiosarcoma in a mediastinal non-seminomatous germ cell tumor that exhibited growing teratoma syndrome during chemotherapy

Herein, we report a case of an angiosarcoma in a mediastinal non-seminomatous germ cell tumor that exhibited growing teratoma syndrome during chemotherapy. A 26-year-old man presented with a giant anterior mediastinal mass, which was diagnosed as a non-seminomatous germ cell tumor. The patient was administered three cycles of chemotherapy (bleomycin, etoposide, and cisplatin), but the mass grew despite normalization of tumor markers. Massive bleeding during thoracic surgery resulted in incomplete resection, and the mass was clinically and pathologically diagnosed as growing teratoma syndrome (only mature teratoma). The residual mass continued to grow, and complete resection was subsequently achieved after a detailed analysis of its vascular anatomy using angiography. The final pathological findings revealed angiosarcoma, which indicated a rare somatic type of mediastinal non-seminomatous germ cell tumor.

Vasoformative Lesions in Mediastinal Mixed Germ Cell Tumors: an Interesting Account of Two Cases Spanning the Benign to Malignant Spectrum

Extragonadal germ cell tumors are most commonly encountered in the anterior mediastinum. The presence of sarcomatous malignancies in these tumors is a rare phenomenon that adversely impacts patient prognosis because of poor response to conventional cisplatin-based chemotherapy. Even more unusual is the presence of florid benign somatic proliferations that overshadow the germ cell component, often resulting in misdiagnosis and inappropriate management. Two young male patients aged 17 and 28 years respectively presented with mass in the anterior mediastinum. Histopathology of both cases revealed mixed germ cell tumor admixed with prominent vascular component. Interestingly, one case showed malignant vasoformative neoplasm (angiosarcoma) while in the other the vascular proliferation was of benign nature (venous hemangioma).

Hepatic angiosarcomatous transformation of a mediastinal germinal cell tumor: A care case report

RATIONALE

Mediastinal nonseminomatous germ cell tumor (NSGCT) is an uncommon entity. Metastatic hepatic sarcomatous transformation is rare.

PATIENT CONCERNS

We report a 24-year-old man with no previous related medical history presented with chest pain and left arm numbness.

DIAGNOSES

The x-ray showed an anterior mediastinal mass. The chest computed tomography (CT) confirmed the presence of a mildly enhancing mass in the same location, without invasion of any vascular structure. A CT-guided biopsy was performed, revealing a primary mediastinal nonseminomatous germ cell tumor (NSGCT), yolk sac histology, with areas of somatic transformation to malignant nerve sheath tumor. After surgery patient was followed-up with imaging. Two years later a CT scan showed a new hepatic hyper vascular lesion, confirmed by a subsequent magnetic resonance imaging (MRI) and positron emission tomography (PET) scan. A CT-guided biopsy revealed a hepatic metastatic transformation to angiosarcoma of the primitive NSGCT.

INTERVENTIONS

The patient went on to received palliative chemotherapy.

OUTCOMES

The patient is being followed-up regularly at the outpatient department.

LESSONS

Because of the potential of metastatic sarcoma arising from germ cell tumors, these patients should undergo periodical follow-up, with periodical scans. PET\CT scan might have a role in the follow-up of these patients.

Mesenchymal tumours of the mediastinum--part II

This is the second part of a two-part review on soft tissue tumours which may be encountered in the mediastinum. This review is based on the 2013 WHO classification of soft tissue tumours and the 2015 WHO classification of tumours of the lung, pleura, thymus and heart and provides an updated overview of mesenchymal tumours that have been reported in the mediastinum.

Mesenchymal tumours of the mediastinum--part I

The mediastinum is an anatomically defined space in which organs and major blood vessels reside with surrounding soft tissue elements. The thymus is an important organ in the mediastinum, and many of the masses encountered in the mediastinum are related to this organ. Most neoplasms diagnosed in the mediastinum are epithelial tumours (thymomas and thymic carcinomas), lymphomas or germ cell tumours. In contrast, soft tissue tumours of the mediastinum are rare. In 1963, Pachter and Lattes systematically reviewed soft tissue pathology of the mediastinum, covering the hitherto described [2, 226, 227] In this review, based on the 2013 WHO classification of soft tissue tumours and the 2015 WHO classification of tumours of the lung, pleura, thymus and heart, we provide an updated overview of mesenchymal tumours that may be encountered in the mediastinum.

Mediastinal Mature Teratoma With Malignant Carcinomatous Transformation (Somatic-Type Malignancy) With Metastatic Course

We report the case of a 76-year-old patient presenting with an anterior mediastinal heterogeneous mass. Surgical biopsy revealed a solid and cystic lesion filled with hair. Pathological examination showed an atypical papillary epithelial lining without other germ cell tumor or immature teratoma associated. The final diagnosis was a mature teratoma of the mediastinum with somatic-type malignancy (carcinomatous transformation). After 8-month follow-up, subcutaneous and lymph node metastatic lesions of the carcinomatous component were identified. Subtyping of the malignant component within germ cell tumors is an important challenge for therapeutic options and prognosis.

Malignant vascular tumors--an update

Although benign hemangiomas are among the most common diagnoses amid connective tissue tumors, sarcomas showing endothelial differentiation (ie, angiosarcoma and epithelioid hemangioendothelioma) represent under 1% of all sarcoma diagnoses, and thus it is likely that fewer than 500 people in the United States are affected each year. Differential diagnosis of malignant vascular tumors can be often quite challenging, either at the low end of the spectrum, distinguishing an epithelioid hemangioendothelioma from an epithelioid hemangioma, or at the high-grade end of the spectrum, between an angiosarcoma and a malignant epithelioid hemangioendothelioma. Within this differential diagnosis both clinico-radiological features (ie, size and multifocality) and immunohistochemical markers (ie, expression of endothelial markers) are often similar and cannot distinguish between benign and malignant vascular lesions. Molecular ancillary tests have long been needed for a more objective diagnosis and classification of malignant vascular tumors, particularly within the epithelioid phenotype. As significant advances have been recently made in understanding the genetic signatures of vascular tumors, this review will take the opportunity to provide a detailed update on these findings. Specifically, this article will focus on the following aspects: (1) pathological and molecular features of epithelioid hemangioendothelioma, including the more common WWTR1-CAMTA1 fusion, as well as the recently described YAP1-TFE3 fusion, identified in a morphological variant of epithelioid hemangioendothelioma; (2) discuss the heterogeneity of angiosarcoma clinical, morphological and genetic spectrum, with particular emphasis of MYC and FLT4 gene amplification in radiation-induced angiosarcoma; and (3) provide a practical guide in the differential diagnosis of epithelioid vascular tumors using molecular testing.

Angiosarcomas and other sarcomas of endothelial origin

Although benign hemangiomas are among the most common diagnoses among connective tissue tumors, angiosarcomas and other sarcomas arising from blood vessels are rare, even among sarcomas. Because endothelial tumors have unique embryonal derivation compared with other sarcomas, it is not surprising they have unique characteristics. Herein are reviewed some of these unique characteristics and therapeutic options for patients with some of these diagnoses, highlighting the potential of new agents for these tumors, which will in all likelihood also impact treatment on more common cancers.

[A case of mediastinal angiosarcoma]

INTRODUCTION

Mediastinal angiosarcoma is a rare intrathoracic tumour and the therapeutic approach remains poorly codified.

CASE REPORT

We report the case of a 65-year-old female patient presenting with chest pain. Further exploration revealed an anterior mediastinal mass with pericardial invasion. Transthoracic biopsy gave the diagnosis of angiosarcoma. Multimodal treatment with neoadjuvant chemotherapy (doxorubicin 20 mg/m(2), Ifosfamide 2500 mg/m(2), Uromitexan® 2500 mg/m(2)) and surgery followed by adjuvant radiotherapy has led to remission of the tumour that has persisted for 12 months.

CONCLUSION

Systematic recording of such conditions in dedicated registries could contribute to enhance the description of the clinical and pathological characteristics, thus helping define the principles of specific management.

Anterior Mediastinal Mass Biopsy and Resection

The perioperative management of the patient with an anterior mediastinal mass (AMM) is viewed as one of the more challenging anesthetic endeavors. Diligent preoperative planning is essential and often involves imaging studies using multiple modalities, pulmonary function assessment, and minimally invasive biopsy for tissue diagnosis prior to arriving in the operating room. Anesthetic induction, often without major risks in most patients, can be catastrophic in AMM patients, with possible complications that include complete airway obstruction and cardiovascular collapse. The authors present the case of a biopsy via anterior mediastinotomy under monitored anesthesia care (MAC)/sedation in a 39-year-old man, who presented with a large AMM causing significant right heart compression without tracheobronchial involvement. This procedure was followed by definitive mass resection approximately 6 weeks later. This review will explore the following: (1) the use of MAC/sedation for AMM biopsy, (2) methods of safely securing the airway in patients undergoing definitive mass resection via median sternotomy, (3) current opinions regarding the need for preoperative pulmonary function testing in these patients, (4) current opinions regarding the need for and timing of cardiopulmonary bypass in these cases, (5) the use of intraoperative transesophageal echocardiography during resection, and (6) the characteristics of mediastinal germ-cell tumors with sarcomatous conversion. Though multiple anesthetic methods have been proposed for the management of patients undergoing tissue biopsy and resection of an AMM, this case report presents 2 successful anesthetic options for 2 distinct surgical procedures. In every instance, the anesthetic management options must be tailored to the unique physiological needs of the patient presenting for surgery.

Mediastinal choriocarcinoma masquerading as relapsed hodgkin lymphoma

Primary mediastinal choriocarcinoma is a rare extragonadal germ cell malignancy. We describe the first case of a patient who developed mediastinal choriocarcinoma after treatment for Hodgkin lymphoma (HL). A 25-year-old man with classic HL, nodular sclerosis subtype, underwent treatment with splenectomy followed by radiation therapy. Unfortunately, his disease relapsed with a paraspinal mass, and he was subsequently treated with MOPP (mechlorethamine, Oncovin, procarbazine, and prednisone) alternating with ABVD (Adriamycin, bleomycin, vinblastine, and dacarbazine). He achieved a complete remission after 6 cycles. Ten years after treatment, the patient presented with a persistent cough, haemoptysis, right supraclavicular lymphadenopathy, and weight loss. His chest X-ray showed opacification of the lower right hemithorax with a widened mediastinum. Given unresponsiveness to several antibiotics and lack of evidence for lung volume loss, there were concerns over lung infiltration with relapsed lymphoma. Transbronchial fine needle aspiration biopsy suggested recurrence of his HL. MOPP alternating with ABVD was again given. Due to disease progression, brachytherapy as well as a cocktail of dexamethasone, cytarabine, and cisplatin were also tried. However, on a subsequent excisional lymph node biopsy, it turned out that the tumour was in fact choriocarcinoma and not relapsed HL. Unfortunately, despite aggressive therapy, the patient's disease rapidly progressed, and he died within 2 weeks.