Vascular neoplasms and non-neoplastic vascular lesions of the spleen.

Vascular neoplasms are among the most common conditions affecting the spleen. The majority of these are idiopathic, benign in nature and asymptomatic and therefore treated with a conservative management. Only rare cases cause splenomegaly and/or chronic consumption coagulopathies, thus requiring splenectomy. Among these, the most common is splenic hemangioma, followed by littoral cell angioma and lymphangioma. Peliosis is a peculiar tumor-like non-neoplastic vascular lesion that diffusely affects the spleen and frequently presents with concomitant hepatic involvement. As a distinctive feature, peliosis can occur as a secondary manifestation of infections, malignancies and in individuals using certain drugs. On the opposite spectrum of clinical behavior lies splenic angiosarcoma, a vascular endothelial malignancy with aggressive presentation and poor prognosis. In some cases the endothelial nature of this neoplasm may not be evident on routine histologic examination and immunohistochemistry is used to disclose such phenotype. The term hemangioendothelioma is rarely used to describe borderline vascular neoplasms which appear more aggressive than conventional hemangiomas, but that do not entirely fulfill the diagnostic criteria for angiosarcoma. Some of these neoplasms coexpress endothelial and histiocytic markers and therefore have been proposed as the borderline counterpart of littoral cell angioma. The existence of hemangioendothelioma as a diagnostic entity per se is debated and this diagnosis should be rendered with caution. The current review aims at highlighting the main histologic features of vascular neoplasms and non-neoplastic vascular lesions of the spleen.