[Sclerosing angiomatoid nodular transformation of spleen]

To study the clinicopathologic features of sclerosing angiomatoid nodular transformation of spleen and its differential diagnosis.

The clinicopathologic characteristics and immunophenotype of 4 cases of sclerosing angiomatoid nodular transformation of spleen were studied.

Histologically, all cases were characterized by multiple angiomatoid nodules of various sizes in a fibrosclerotic stroma. The nodules were round and sometimes convoluted. They were composed of slit-like, irregular-shaped or slightly dilated vascular spaces lined by plump endothelial cells and interspersed with a population of spindly or ovoid cells. Immunohistochemical study showed a heterogeneous staining pattern, with the lining cells of the small capillaries expressing CD34 and those of the sinusoid-like structures expressing CD8. CD31 highlighted both the lining cells and interspersed cells, resulting in a complex meshwork. The lining cells were also focally positive for CD68. Smooth muscle actin revealed conglomerates of spindly shaped cells around and between the vascular channels. These spindly shaped cells in the intervening stroma were focally positive for actin, but negative for desmin, CD21 and CD35.

Sclerosing angiomatoid nodular transformation is a rarely encountered benign lesion of the spleen, which should be distinguished from other angiomatoid tumors and tumor-like lesions.