Epithelioid haemangioendothelioma

A tumour of variable malignant potential that is composed of epithelioid or spindle cells growing along preformed vessels or forming new vessels. Epithelioid haemangioendothelioma presents between 12 and 86 years (mean 47 years) {807, 1150}. Its overall incidence is unknown, but more are reported in females (61%) than in males (39%) {807, 1150}. Risk factors are not known; the

Fig. 8.69 Epithelioid haemangioendothelioma. There is extensive destruction of liver cell plates. Note the intracellular vascular lumina (arrow).

Fig. 8.70 Epithelioid haemangioendothelioma. A, B Tumour cells form polypoid projections in dilated periportal sinusoids. C Dendritic tumour cells, some having intracellular vascular lumina appearing as small vacuoles. A terminal hepatic venule is infiltrated by tumour. D Tumour cells express factor VIII-related antigen.

Fig. 8.70 Epithelioid haemangioendothelioma. A, B Tumour cells form polypoid projections in dilated periportal sinusoids. C Dendritic tumour cells, some having intracellular vascular lumina appearing as small vacuoles. A terminal hepatic venule is infiltrated by tumour. D Tumour cells express factor VIII-related antigen.

suggestion of a relationship to oral contraceptive use has not been validated {1270}. Epithelioid haemangioendothe-lioma causes systemic symptoms (weakness, malaise, anorexia, episodic vomiting, upper abdominal pain, and weight loss) and hepato-splenomegaly {807, 1150}. Some patients develop jaundice and liver failure. Uncommon modes of presentation include the Budd-Chiari syndrome {2040} or portal hypertension. Macroscopy. Macroscopically, lesions are usually multifocal; ill-defined lesions scattered throughout the liver vary from a few millimeters to several centimeters in greatest dimension. They are firm, tan to white on sectioning, and often have a hyperaemic periphery; calcification may be evident grossly.

Histopathology. The tumour nodules are ill-defined, and often involve multiple contiguous acini. In actively proliferating lesions the acinar landmarks, such as terminal hepatic venules (THV) and portal areas, can be recognized despite extensive infiltration by the tumour. The cells grow along preexisting sinusoids, THV, and portal vein branches, and often invade Glisson capsule. Growth within the acini is associated with gradual atrophy and eventual disappearance of liver cell plates. Intravascular growth may be in the form of a solid plug, or a polypoid or tuft-like projection.

Neoplastic cell are either 'dendritic', with spindle or irregular shapes and multiple interdigitating processes, 'epithelioid', with a more rounded shape and an abundant cytoplasm, or 'intermediate'. Nuclear atypia and mitoses are mainly observed in the epithelioid cells. Cyto-plasmic vacuoles, representing intracel-lular vascular lumens, are often identified and may contain erythrocytes. The tumour cells synthesize factor VIII-related antigen (von Willebrand factor), which can be demonstrated in the cytoplasm or in the neoplastic vascular lumens. Other endothelial cell markers, such as CD31 and CD34, are also positive. The stroma can have a myxoid appearance due to an abundance of sulphated mucopolysaccharide. Reticulin fibres surround nests of tumour cells. Basement membrane can be demonstrated around the cells by the PAS stain, as well as ultra-structurally and immunohistochemically. Variable numbers of smooth muscle cells surround the basement membrane. As the lesions evolve they are associated with progressive fibrosis and calcification. Eventually, tumour cells (and indeed, the vascular nature of the lesion) may be difficult if not impossible to recognize in the densely sclerosed areas. Needle biopsy specimens taken from such areas often pose diagnostic problems. The histopa-thological differential diagnosis includes angiosarcoma and cholangiocarcinoma. Angiosarcoma is much more destructive than epithelioid haemangioendothelioma, obliterates acinar landmarks and results in cavity formation. Cells of cholangiocar-cinoma are arranged in a tubular or glandular pattern, and often produce mucin; the cells are cytokeratin positive and do not express endothelial cell markers. Prognosis. The clinical outcome of epithelioid haemangioendothelioma is unpredictable, with some patients having a fulminant course and others surviving many years with no therapy. A recent study {1150} showed a correlation between high cellularity of the tumour with a poor clinical outcome. Successful treatment includes resection, when feasible, and liver transplantation.

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