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| Tumor | Gross characteristics | Microscopy/histologic features | Immunohistochemistry |
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| Angiosarcoma | Ill-defined, diffusely infiltrative spongy nodules with hemorrhage. Extensive and diffuse involvement of liver. | The tumor consists of malignant endothelial cells which grow along preexisting vascular channels and hepatic sinusoids. It shows solid and pseudopapillary patterns. Necrosis and hemorrhage present. Plump spindle cells with large pleomorphic nuclei. | Positive for CD31, CD34, factor VIII
Weibel-Palade bodies on electron microscopy. |
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| Epithelioid hemangioendothelioma | Multiple, tan-gray, firm, circumscribed and focally confluent nodules up to 12 cm with infiltrative borders. It may show central calcification or ossification. | Tumor exhibits zonal pattern, with central sclerosis or hyalinization and tumor cells at the periphery in a sinusoidal proliferation. Tumor forms papillary tufting and glomeruloid structures within portal vein branches. Eosinophilic epithelioid tumor cells typically show vacuolated signet-ring-like features representing intracytoplasmic lumina sometimes containing erythrocytes. | Positive for factor VIII, CD31, CD34, cytokeratin (50%)
Weibel-Palade bodies, and intermediate filaments on electron microscopy. |
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| Hepatocellular carcinoma (HCC) | Solitary, multinodular or diffusely infiltrative soft, yellow-green or reddish mass in a background of cirrhosis. Smaller satellite nodules around large mass. High propensity of tumor to invade into the portal veins. Hemorrhage and necrosis are common. | Major histologic patterns are trabecular (plate-like), pseudoglandular (acinar) and compact (solid) types. Cells are polygonal with distinct cell membranes, abundant granular eosinophilic cytoplasm, higher nucleocytoplasmic ratio than normal, round nuclei with coarse chromatin and may have prominent nucleoli. Presence of sinusoidal vessels surrounding tumor cells is an important diagnostic feature. Intranuclear inclusions including eosinophilic hyaline bodies, Mallory hyaline, and fat droplets may be present. | Positive for HepPar1 (90% of all HCCs) and glypican-3, canalicular pattern of staining with polyclonal CEA, AFP (25%). |
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Kaposi sarcoma
(aggressive variant associated with AIDS) | Hemorrhagic multifocal spongy nodules 5–7 cm. | Lesions centered on portal tracts with poorly vasoformative spindle-cell proliferation accompanied by red blood cell extravasation and focal deposition of hemosiderin. Cytoplasmic eosinophilic hyaline globules are a typical finding. | Positive for membranous/cytoplasmic CD31 and CD34 and nuclear HHV8. |
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Undifferentiated sarcoma
(most common in children age 6–10 years) | Well-demarcated, solitary, unencapsulated lesion. Cut surface is variegated with solid and cystic/gelatinous areas, with necrosis and hemorrhage. | Tumor consists of loosely arranged, spindle-pleomorphic cells embedded in an abundant mucopolysaccharide-rich myxoid matrix. Dilated bile ducts and PAS-positive diastase-resistant globules found within the tumor cells; tumor not particularly vascular. | Positive for Vimentin, focally positive for Keratin;
CD31 negative. |
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Peliosis hepatis
(associated with exposure to anabolic steroids, tuberculosis, and AIDS) | Honeycombed liver with multiple round, red-purple, blood filled spaces, range from 1mm to several cm. | Lesion consists of blood-filled spaces surrounded by a pseudocapsule of fibrin and early collagen. Rarely endothelial lining visible.
B. henselae (bacillary angiomatosis) cases have small blood vessel proliferation and spindle cells. | Positive for Warthin-Starry stain (Bartonella henselae infection in HIV patients). |
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