Vascular
tumors of the spleen include several different entities, some of which are unique to that organ. Twenty-two such proliferations were studied, including 10
hemangiomas, six littoral cell angiomas, four
angiosarcomas, and two
hamartomas. The
hemangiomas included seven with localized
tumors and three with diffuse
angiomatosis of the spleen. All cases were studied by
paraffin section immunohistochemistry with a large panel of
antibodies. In addition, all cases were studied for the presence of the Kaposi's sarcoma-associated herpesvirus (KSHV) using the polymerase chain reaction. The morphologic findings were similar to those previously reported. All proliferations were
vimentin positive, and one
angiosarcoma was focally
keratin positive. All cases reacted for CD31, whereas 20 of 22 were positive for von Willebrand's factor and 19 of 22 were positive for Ulex europeaus. CD34 expression in lining cells was identified in 10 of 10
hemangiomas, two of four
angiosarcomas, and one of two
hamartomas, whereas all six cases of
littoral cell angioma were negative. CD68 was expressed in all cases of
littoral cell angioma but was also positive in all three diffuse
hemangiomas, two of seven localized
hemangiomas, and two of four
angiosarcomas. CD21 expression was restricted to the lining cells of
littoral cell angioma, and CD8 expression was only identified in two of two
hamartomas and two of four
angiosarcomas. KSHV was not detected in any of the cases. These findings suggest that there are distinct immunophenotypic as well as morphologic features of splenic vascular
tumors. Littoral cell angiomas have a characteristic CD34-/CD68+/CD21+/CD8- immunophenotype and
hamartomas have a characteristic CD68-/CD21-/CD8+ phenotype. The frequent CD68 expression in diffuse
hemangioma suggests an immunophenotypic difference from localized
hemangioma of the spleen.