Isolated diffuse hemangiomatosis of the spleen with Kasabach-Merritt-like syndrome

Aims: Diffuse haemangiomatosis of the spleen is a rare benign vascular condition occurring as a manifestation of systemic angiomatosis or, less commonly confirmed to the spleen. It is sometimes accompanied by severe disturbance of blood coagulation. The goal of this study was to characterize an additional case of isolated diffuse haemangiomatosis of the spleen and to determine the histogenesis of this lesion which remains obscure. Methods and results: We describe a case of isolated diffuse haemangiomatosis of the spleen in which histological and immunohistological findings suggested the possibility of a malformative tumour-like lesion. The pathological cavernous vessels were distributed randomly through the red pulp, without continuity with sinuses. The endothelial cells expressed vimentin, factor VIII related antigen and CD34, but not CD8. Some cells lining the sinus lumen expressed CD68, lysozyme and myeloperoxidase. In addition, trabecular veins presented with intimal thickening. These results allow malting a diagnosis between diffuse haemangiomatosis and other tumours/tumour-like lesions of the spleen, especially littoral cell angioma, splenoma and peliosis. Conclusion: If diffuse haemangiomatosis is usually classified as a benign proliferation of endothelial cells, we suggest that diffuse haemangiomatosis, when confined to the spleen, could be a tumour-like vascular lesion. In this hypothesis, the aetiology may be hamartomatous or malformative as is suspected in arterio-venous haemangioma of the lower extremities. The histogenesis is still questionable and no definitive proof in favour of one or the other hypothesis has been reported.