Primary angiosarcoma of the mediastinum: light and electron microscopic demonstration of Factor VIII-related antigen in neoplastic cells

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 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.

Primary hemangiosarcoma of the mediastinum

A case of a 44-year-old female who had an intrathoracic mass that was found to be a hemangiosarcoma of the anterior mediastinum is reported. Radical surgical incision through a right anterior thoracotomy was performed, followed by post-operative radiotherapy. Since this is a rare tumor at this location, the clinical and radiological findings, the histopathological appearances and its therapeutic management are discussed. Radiologists, surgeons and oncologists should in the differential diagnosis of a mediastinal mass include that of a tumor of vascular origin, even if it is rare. Radical excision followed by post-operative radiotherapy, especially in cases where the tumor has been partially excised, is the treatment of choice.

Cutaneous epithelioid angiosarcoma: a clinicopathological study of four cases

Four cases of cutaneous epithelioid angiosarcoma are described together with the potential diagnostic trap of mistaking these tumours for poorly differentiated carcinoma or malignant melanoma. The immunophenotypic profile using four endothelial markers showed positive staining in all cases for factor VIII related antigen in a predominantly paranuclear dot-like fashion and for CD31 (JC70); in three cases for CD34 (QB-END/10) and in two cases with UEA-1. All four cases were cytokeratin (CAM 5.2 and AE1/AE3) negative in contrast to the positive staining reported at non-cutaneous sites. Aberrant S-100 protein expression was seen in one case. In two cases subsequent recurrences showed better differentiation than the original tumour. Electronmicroscopy confirmed the absence of non-endothelial lines of differentiation but failed to reveal Weibel-Palade bodies.

Cytokeratin expression in epithelioid vascular neoplasms

Seven epithelioid and eight non-epithelioid vascular tumors were studied by the avidin-biotin-peroxidase method for the presence of endothelial- and epithelial-associated markers, using Ulex europaeus agglutinin-1 (UEA-1) lectin, and antibodies directed against factor VIII-related antigen, (FVIII-RA), vimentin, keratin, carcinoembryonic antigen, and epithelial membrane antigen. The cases included four epithelioid hemangiomas, two epithelioid hemangioendotheliomas (EHE), one epithelioid angiosarcoma (EAS), four common non-epithelioid capillary hemangiomas, and four non-epithelioid angiosarcomas. Staining for FVIII-RA, UEA-1, and vimentin were observed in all cases. The EAS showed staining for keratin in formalin-fixed, paraffin-embedded sections and in frozen sections. Staining for keratin was also observed in frozen sections of one EHE. Both keratin-positive vascular tumors were confirmed with electron microscopy. Carcinoembryonic antigen and epithelial membrane antigen stains were negative in all cases. Our results show that the epithelioid vascular tumors EHE and EAS, in addition to staining for the endothelial markers and vimentin, may also express the epithelial marker keratin. This is important since these tumors may closely resemble carcinomas by routine light microscopy. This study further underscores the importance of using a broad panel of immunohistochemical markers in the diagnostic workup of soft-tissue neoplasms.

Ultrastructural and immunocytochemical observations on angiosarcomas

Forty-seven angiosarcomas have been studied by light and electron microscopy. Neoplastic endothelial cells do not consistently display specific ultrastructural features, but certain aspects of the fine structure of the cells and their arrangement can be useful to establish or confirm the diagnosis. Experience with the common endothelial cell markers as diagnostic aids is briefly reviewed.

Malignant epithelioid hemangioendothelioma of the colon. Report of a case

Angiosarcoma of the colon with epithelioid and histiocytoid features, a malignant counterpart of epithelioid hemangioendothelioma, was observed in a 72-year-old man. The disease first manifested as a right cervical mass, with the histologic appearance of malignant, undifferentiated, large-cell epithelioid neoplasm. Light microscopy of the colonic tumor disclosed angiosarcoma, with active erythrophagocytosis and positive immunoperoxidase reactions to lysozyme, alpha-1-antitrypsin, and alpha-1-antichymotrypsin. Ultrastructural features of the tumor cells were those of intermediate between endothelial and histiocytic cells. The disease took a rapid fatal course with recurrence, peritoneal dissemination, and massive peritoneal hemorrhage. The cause remains unknown.

The histogenesis of angiosarcoma of the face and scalp: an immunohistochemical and ultrastructural study

Thirteen cases of angiosarcoma of the face and scalp have been examined using immunohistochemistry and electron microscopy. Endothelial cell markers have been employed in an immunoperoxidase technique on tissue that has either been routinely processed, periodate-lysine paraformaldehyde fixed (PLP) and cold processed, or fixed in methacarn. A consistent pattern of endothelial cell labeling was only achieved in the PLP fixed tissue. In this fixative the angiosarcomas were factor VIII related antigen negative, Ulex europaeus lectin positive, laminin positive, unlabelled by the monoclonal antibody PAL-E, and positively labelled by the monoclonal antibody EN4. Ultrastructural examination of four cases showed evidence of vascular lumina in all tumours. Weibel-Palade bodies were seen in only one case but three tumours showed some evidence of tight junction formation and marginal folding. Thus, our cell marker studies can be interpreted as consistent with a lymphatic derivation for this type of angiosarcoma but in contra-distinction the ultrastructural studies showed tumour channels with features suggestive of blood vessel differentiation.

Ultrastructural localization of factor VIII procoagulant antigen in human liver hepatocytes

Factor VIII is generally believed to circulate in blood as a multimeric complex of two glycoproteins which are physiologically and immunologically distinct. One component of the factor VIII complex is factor VIII procoagulant activity (FVIII:C) which is associated with factor VIII/procoagulant antigen (FVIII:Ag, formerly FVIII/CAg). The second, larger unit of the complex is factor VIII/von Willebrand factor (vWF:Ag, formerly factor VIII-related antigen or FVIIIRAg). FVIII:C has anti-haemophilic activity and is defective or deficient in patients with classical haemophilia, and vWF:Ag is absent in patients with von Willebrand disease. FVIII:Ag was demonstrated recently in endothelial cells lining hepatic sinusoids, by using immunoperoxidase staining and light microscopy, whereas biochemical data had indicated its presence predominantly in the hepatocyte fractions and in lesser amounts in endothelial cells. Moreover, recent hybridization experiments detected FVIII:C messenger RNA in liver and kidney tissues. Despite several efforts, the cells responsible for FVIII:C synthesis have not been unequivocally identified. Here we use protein A-gold complex labelling to demonstrate the ultrastructural localization of FVIII:C in human liver cells; the results indicate that hepatocytes may synthesize FVIII:Ag.

Comparison of tumour markers in malignant mesothelioma and pulmonary adenocarcinoma

Immunohistological methods were used to investigate the presence of carcinoembryonic antigen, beta 1 pregnancy specific glycoprotein, beta subunit of human chorionic gonadotrophin, human placental lactogen, calcitonin, and keratin in formalin fixed tissue from 29 malignant mesotheliomas and 27 pulmonary adenocarcinomas. Malignant mesotheliomas were negative for tumour markers except for the beta subunit of human chorionic gonadotrophin and keratin, one and 13 cases respectively being positive for these. Pulmonary adenocarcinomas, however, were frequently positive for tumour markers--namely, carcinoembryonic antigen, beta 1 pregnancy specific glycoprotein, beta subunit of human chorionic gonadotrophin, human placental lactogen, calcitonin, and keratin. The presence of carcinoembryonic antigen and beta 1 pregnancy specific glycoprotein within an intrathoracic tumour is strong evidence against its being of mesothelial origin.