Isolated diffuse hemangiomatosis of the spleen: case report and review of literature.

Small localized hemangiomas are common neoplasms of the spleen. Isolated diffuse splenic hemangiomatosis, however, is very rare. This lesion can be accompanied by severe hypersplenism and other complications. We report on a case with significant splenomegaly caused by diffuse hemangiomatosis, which was an incidental finding without any clinical disorders. After splenectomy, the normal parenchyma was found to be widely replaced by multiple spongy nodules. Histologically, cavernous vessels were distributed throughout the whole organ, with endothelial cells expressing vimentin, factor VIII and CD 31, but not CD8. Splenic sinus lining cells exhibited a strongly positive reaction with CD8, which became faint and disrupted in highly dilated sinuses in the vicinity of cavernous vessels. In some areas, there seemed to be a gradual transition from cystically dilated splenic sinuses to cavernous vessels. The differential diagnosis must consider other splenic vascular tumors, such as littoral cell angioma, lymphangioma, peliosis of the spleen, and hamartoma. The pathogenesis of diffuse splenic hemangiomatosis is controversial, and a malformative or neoplastic origin is under debate. A derivation from splenic sinusoidal cells was suggested by some authors, but was rejected by others. Our findings cannot exclude a neoplastic origin from splenic sinuses but, finally, the etiology and pathogenesis of this vascular lesion remain uncertain.